diff options
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 3263 |
1 files changed, 2622 insertions, 641 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index d41b70fe4918..d0a2847a4bb0 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -9,51 +9,112 @@ * - Andrew D. Balsa (code cleanup). */ #include <linux/init.h> -#include <linux/utsname.h> #include <linux/cpu.h> #include <linux/module.h> #include <linux/nospec.h> #include <linux/prctl.h> #include <linux/sched/smt.h> #include <linux/pgtable.h> +#include <linux/bpf.h> +#include <linux/kvm_types.h> #include <asm/spec-ctrl.h> #include <asm/cmdline.h> #include <asm/bugs.h> #include <asm/processor.h> #include <asm/processor-flags.h> -#include <asm/fpu/internal.h> +#include <asm/fpu/api.h> #include <asm/msr.h> #include <asm/vmx.h> #include <asm/paravirt.h> -#include <asm/alternative.h> -#include <asm/set_memory.h> -#include <asm/intel-family.h> +#include <asm/cpu_device_id.h> #include <asm/e820/api.h> #include <asm/hypervisor.h> #include <asm/tlbflush.h> +#include <asm/cpu.h> #include "cpu.h" -static void __init spectre_v1_select_mitigation(void); -static void __init spectre_v2_select_mitigation(void); -static void __init ssb_select_mitigation(void); -static void __init l1tf_select_mitigation(void); -static void __init mds_select_mitigation(void); -static void __init mds_print_mitigation(void); -static void __init taa_select_mitigation(void); -static void __init srbds_select_mitigation(void); +/* + * Speculation Vulnerability Handling + * + * Each vulnerability is handled with the following functions: + * <vuln>_select_mitigation() -- Selects a mitigation to use. This should + * take into account all relevant command line + * options. + * <vuln>_update_mitigation() -- This is called after all vulnerabilities have + * selected a mitigation, in case the selection + * may want to change based on other choices + * made. This function is optional. + * <vuln>_apply_mitigation() -- Enable the selected mitigation. + * + * The compile-time mitigation in all cases should be AUTO. An explicit + * command-line option can override AUTO. If no such option is + * provided, <vuln>_select_mitigation() will override AUTO to the best + * mitigation option. + */ -/* The base value of the SPEC_CTRL MSR that always has to be preserved. */ +/* The base value of the SPEC_CTRL MSR without task-specific bits set */ u64 x86_spec_ctrl_base; -EXPORT_SYMBOL_GPL(x86_spec_ctrl_base); + +/* The current value of the SPEC_CTRL MSR with task-specific bits set */ +DEFINE_PER_CPU(u64, x86_spec_ctrl_current); +EXPORT_PER_CPU_SYMBOL_GPL(x86_spec_ctrl_current); + +/* + * Set when the CPU has run a potentially malicious guest. An IBPB will + * be needed to before running userspace. That IBPB will flush the branch + * predictor content. + */ +DEFINE_PER_CPU(bool, x86_ibpb_exit_to_user); +EXPORT_PER_CPU_SYMBOL_GPL(x86_ibpb_exit_to_user); + +u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB; + +static u64 __ro_after_init x86_arch_cap_msr; + static DEFINE_MUTEX(spec_ctrl_mutex); +void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk; + +static void __init set_return_thunk(void *thunk) +{ + x86_return_thunk = thunk; + + pr_info("active return thunk: %ps\n", thunk); +} + +/* Update SPEC_CTRL MSR and its cached copy unconditionally */ +static void update_spec_ctrl(u64 val) +{ + this_cpu_write(x86_spec_ctrl_current, val); + wrmsrq(MSR_IA32_SPEC_CTRL, val); +} + /* - * The vendor and possibly platform specific bits which can be modified in - * x86_spec_ctrl_base. + * Keep track of the SPEC_CTRL MSR value for the current task, which may differ + * from x86_spec_ctrl_base due to STIBP/SSB in __speculation_ctrl_update(). */ -static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS; +void update_spec_ctrl_cond(u64 val) +{ + if (this_cpu_read(x86_spec_ctrl_current) == val) + return; + + this_cpu_write(x86_spec_ctrl_current, val); + + /* + * When KERNEL_IBRS this MSR is written on return-to-user, unless + * forced the update can be delayed until that time. + */ + if (!cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS)) + wrmsrq(MSR_IA32_SPEC_CTRL, val); +} + +noinstr u64 spec_ctrl_current(void) +{ + return this_cpu_read(x86_spec_ctrl_current); +} +EXPORT_SYMBOL_GPL(spec_ctrl_current); /* * AMD specific MSR info for Speculative Store Bypass control. @@ -69,120 +130,64 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb); /* Control unconditional IBPB in switch_mm() */ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb); -/* Control MDS CPU buffer clear before returning to user space */ -DEFINE_STATIC_KEY_FALSE(mds_user_clear); -EXPORT_SYMBOL_GPL(mds_user_clear); -/* Control MDS CPU buffer clear before idling (halt, mwait) */ -DEFINE_STATIC_KEY_FALSE(mds_idle_clear); -EXPORT_SYMBOL_GPL(mds_idle_clear); - -void __init check_bugs(void) -{ - identify_boot_cpu(); +/* Control IBPB on vCPU load */ +DEFINE_STATIC_KEY_FALSE(switch_vcpu_ibpb); +EXPORT_SYMBOL_FOR_KVM(switch_vcpu_ibpb); - /* - * identify_boot_cpu() initialized SMT support information, let the - * core code know. - */ - cpu_smt_check_topology(); - - if (!IS_ENABLED(CONFIG_SMP)) { - pr_info("CPU: "); - print_cpu_info(&boot_cpu_data); - } +/* Control CPU buffer clear before idling (halt, mwait) */ +DEFINE_STATIC_KEY_FALSE(cpu_buf_idle_clear); +EXPORT_SYMBOL_GPL(cpu_buf_idle_clear); - /* - * Read the SPEC_CTRL MSR to account for reserved bits which may - * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD - * init code as it is not enumerated and depends on the family. - */ - if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) - rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); +/* + * Controls whether l1d flush based mitigations are enabled, + * based on hw features and admin setting via boot parameter + * defaults to false + */ +DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush); - /* Allow STIBP in MSR_SPEC_CTRL if supported */ - if (boot_cpu_has(X86_FEATURE_STIBP)) - x86_spec_ctrl_mask |= SPEC_CTRL_STIBP; +#undef pr_fmt +#define pr_fmt(fmt) "mitigations: " fmt - /* Select the proper CPU mitigations before patching alternatives: */ - spectre_v1_select_mitigation(); - spectre_v2_select_mitigation(); - ssb_select_mitigation(); - l1tf_select_mitigation(); - mds_select_mitigation(); - taa_select_mitigation(); - srbds_select_mitigation(); +static void __init cpu_print_attack_vectors(void) +{ + pr_info("Enabled attack vectors: "); - /* - * As MDS and TAA mitigations are inter-related, print MDS - * mitigation until after TAA mitigation selection is done. - */ - mds_print_mitigation(); + if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL)) + pr_cont("user_kernel, "); - arch_smt_update(); + if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER)) + pr_cont("user_user, "); -#ifdef CONFIG_X86_32 - /* - * Check whether we are able to run this kernel safely on SMP. - * - * - i386 is no longer supported. - * - In order to run on anything without a TSC, we need to be - * compiled for a i486. - */ - if (boot_cpu_data.x86 < 4) - panic("Kernel requires i486+ for 'invlpg' and other features"); + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST)) + pr_cont("guest_host, "); - init_utsname()->machine[1] = - '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86); - alternative_instructions(); + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST)) + pr_cont("guest_guest, "); - fpu__init_check_bugs(); -#else /* CONFIG_X86_64 */ - alternative_instructions(); + pr_cont("SMT mitigations: "); - /* - * Make sure the first 2MB area is not mapped by huge pages - * There are typically fixed size MTRRs in there and overlapping - * MTRRs into large pages causes slow downs. - * - * Right now we don't do that with gbpages because there seems - * very little benefit for that case. - */ - if (!direct_gbpages) - set_memory_4k((unsigned long)__va(0), 1); -#endif + switch (smt_mitigations) { + case SMT_MITIGATIONS_OFF: + pr_cont("off\n"); + break; + case SMT_MITIGATIONS_AUTO: + pr_cont("auto\n"); + break; + case SMT_MITIGATIONS_ON: + pr_cont("on\n"); + } } +/* + * NOTE: This function is *only* called for SVM, since Intel uses + * MSR_IA32_SPEC_CTRL for SSBD. + */ void -x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) +x86_virt_spec_ctrl(u64 guest_virt_spec_ctrl, bool setguest) { - u64 msrval, guestval, hostval = x86_spec_ctrl_base; + u64 guestval, hostval; struct thread_info *ti = current_thread_info(); - /* Is MSR_SPEC_CTRL implemented ? */ - if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) { - /* - * Restrict guest_spec_ctrl to supported values. Clear the - * modifiable bits in the host base value and or the - * modifiable bits from the guest value. - */ - guestval = hostval & ~x86_spec_ctrl_mask; - guestval |= guest_spec_ctrl & x86_spec_ctrl_mask; - - /* SSBD controlled in MSR_SPEC_CTRL */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || - static_cpu_has(X86_FEATURE_AMD_SSBD)) - hostval |= ssbd_tif_to_spec_ctrl(ti->flags); - - /* Conditional STIBP enabled? */ - if (static_branch_unlikely(&switch_to_cond_stibp)) - hostval |= stibp_tif_to_spec_ctrl(ti->flags); - - if (hostval != guestval) { - msrval = setguest ? guestval : hostval; - wrmsrl(MSR_IA32_SPEC_CTRL, msrval); - } - } - /* * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported. @@ -213,23 +218,86 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) speculation_ctrl_update(tif); } } -EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl); +EXPORT_SYMBOL_FOR_KVM(x86_virt_spec_ctrl); static void x86_amd_ssb_disable(void) { u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask; if (boot_cpu_has(X86_FEATURE_VIRT_SSBD)) - wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD); + wrmsrq(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD); else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD)) - wrmsrl(MSR_AMD64_LS_CFG, msrval); + wrmsrq(MSR_AMD64_LS_CFG, msrval); } #undef pr_fmt #define pr_fmt(fmt) "MDS: " fmt +/* + * Returns true if vulnerability should be mitigated based on the + * selected attack vector controls. + * + * See Documentation/admin-guide/hw-vuln/attack_vector_controls.rst + */ +static bool __init should_mitigate_vuln(unsigned int bug) +{ + switch (bug) { + /* + * The only runtime-selected spectre_v1 mitigations in the kernel are + * related to SWAPGS protection on kernel entry. Therefore, protection + * is only required for the user->kernel attack vector. + */ + case X86_BUG_SPECTRE_V1: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL); + + case X86_BUG_SPECTRE_V2: + case X86_BUG_RETBLEED: + case X86_BUG_L1TF: + case X86_BUG_ITS: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST); + + case X86_BUG_SPECTRE_V2_USER: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST); + + /* + * All the vulnerabilities below allow potentially leaking data + * across address spaces. Therefore, mitigation is required for + * any of these 4 attack vectors. + */ + case X86_BUG_MDS: + case X86_BUG_TAA: + case X86_BUG_MMIO_STALE_DATA: + case X86_BUG_RFDS: + case X86_BUG_SRBDS: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST) || + cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST); + + case X86_BUG_GDS: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST) || + cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST) || + (smt_mitigations != SMT_MITIGATIONS_OFF); + + case X86_BUG_SPEC_STORE_BYPASS: + return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER); + + case X86_BUG_VMSCAPE: + return cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST); + + default: + WARN(1, "Unknown bug %x\n", bug); + return false; + } +} + /* Default mitigation for MDS-affected CPUs */ -static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL; +static enum mds_mitigations mds_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_AUTO : MDS_MITIGATION_OFF; static bool mds_nosmt __ro_after_init = false; static const char * const mds_strings[] = { @@ -238,33 +306,95 @@ static const char * const mds_strings[] = { [MDS_MITIGATION_VMWERV] = "Vulnerable: Clear CPU buffers attempted, no microcode", }; +enum taa_mitigations { + TAA_MITIGATION_OFF, + TAA_MITIGATION_AUTO, + TAA_MITIGATION_UCODE_NEEDED, + TAA_MITIGATION_VERW, + TAA_MITIGATION_TSX_DISABLED, +}; + +/* Default mitigation for TAA-affected CPUs */ +static enum taa_mitigations taa_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_TAA) ? TAA_MITIGATION_AUTO : TAA_MITIGATION_OFF; + +enum mmio_mitigations { + MMIO_MITIGATION_OFF, + MMIO_MITIGATION_AUTO, + MMIO_MITIGATION_UCODE_NEEDED, + MMIO_MITIGATION_VERW, +}; + +/* Default mitigation for Processor MMIO Stale Data vulnerabilities */ +static enum mmio_mitigations mmio_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_MMIO_STALE_DATA) ? MMIO_MITIGATION_AUTO : MMIO_MITIGATION_OFF; + +enum rfds_mitigations { + RFDS_MITIGATION_OFF, + RFDS_MITIGATION_AUTO, + RFDS_MITIGATION_VERW, + RFDS_MITIGATION_UCODE_NEEDED, +}; + +/* Default mitigation for Register File Data Sampling */ +static enum rfds_mitigations rfds_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_RFDS) ? RFDS_MITIGATION_AUTO : RFDS_MITIGATION_OFF; + +/* + * Set if any of MDS/TAA/MMIO/RFDS are going to enable VERW clearing on exit to + * userspace *and* on entry to KVM guests. + */ +static bool verw_clear_cpu_buf_mitigation_selected __ro_after_init; + static void __init mds_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_MDS)) { mds_mitigation = MDS_MITIGATION_OFF; return; } - if (mds_mitigation == MDS_MITIGATION_FULL) { - if (!boot_cpu_has(X86_FEATURE_MD_CLEAR)) - mds_mitigation = MDS_MITIGATION_VMWERV; + if (mds_mitigation == MDS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_MDS)) + mds_mitigation = MDS_MITIGATION_FULL; + else + mds_mitigation = MDS_MITIGATION_OFF; + } - static_branch_enable(&mds_user_clear); + if (mds_mitigation == MDS_MITIGATION_OFF) + return; - if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) && - (mds_nosmt || cpu_mitigations_auto_nosmt())) - cpu_smt_disable(false); - } + verw_clear_cpu_buf_mitigation_selected = true; } -static void __init mds_print_mitigation(void) +static void __init mds_update_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) + if (!boot_cpu_has_bug(X86_BUG_MDS)) return; + /* If TAA, MMIO, or RFDS are being mitigated, MDS gets mitigated too. */ + if (verw_clear_cpu_buf_mitigation_selected) + mds_mitigation = MDS_MITIGATION_FULL; + + if (mds_mitigation == MDS_MITIGATION_FULL) { + if (!boot_cpu_has(X86_FEATURE_MD_CLEAR)) + mds_mitigation = MDS_MITIGATION_VMWERV; + } + pr_info("%s\n", mds_strings[mds_mitigation]); } +static void __init mds_apply_mitigation(void) +{ + if (mds_mitigation == MDS_MITIGATION_FULL || + mds_mitigation == MDS_MITIGATION_VMWERV) { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) && + (mds_nosmt || smt_mitigations == SMT_MITIGATIONS_ON)) + cpu_smt_disable(false); + } +} + static int __init mds_cmdline(char *str) { if (!boot_cpu_has_bug(X86_BUG_MDS)) @@ -289,15 +419,6 @@ early_param("mds", mds_cmdline); #undef pr_fmt #define pr_fmt(fmt) "TAA: " fmt -enum taa_mitigations { - TAA_MITIGATION_OFF, - TAA_MITIGATION_UCODE_NEEDED, - TAA_MITIGATION_VERW, - TAA_MITIGATION_TSX_DISABLED, -}; - -/* Default mitigation for TAA-affected CPUs */ -static enum taa_mitigations taa_mitigation __ro_after_init = TAA_MITIGATION_VERW; static bool taa_nosmt __ro_after_init; static const char * const taa_strings[] = { @@ -307,10 +428,13 @@ static const char * const taa_strings[] = { [TAA_MITIGATION_TSX_DISABLED] = "Mitigation: TSX disabled", }; -static void __init taa_select_mitigation(void) +static bool __init taa_vulnerable(void) { - u64 ia32_cap; + return boot_cpu_has_bug(X86_BUG_TAA) && boot_cpu_has(X86_FEATURE_RTM); +} +static void __init taa_select_mitigation(void) +{ if (!boot_cpu_has_bug(X86_BUG_TAA)) { taa_mitigation = TAA_MITIGATION_OFF; return; @@ -319,64 +443,68 @@ static void __init taa_select_mitigation(void) /* TSX previously disabled by tsx=off */ if (!boot_cpu_has(X86_FEATURE_RTM)) { taa_mitigation = TAA_MITIGATION_TSX_DISABLED; - goto out; + return; } - if (cpu_mitigations_off()) { - taa_mitigation = TAA_MITIGATION_OFF; - return; + /* Microcode will be checked in taa_update_mitigation(). */ + if (taa_mitigation == TAA_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_TAA)) + taa_mitigation = TAA_MITIGATION_VERW; + else + taa_mitigation = TAA_MITIGATION_OFF; } - /* - * TAA mitigation via VERW is turned off if both - * tsx_async_abort=off and mds=off are specified. - */ - if (taa_mitigation == TAA_MITIGATION_OFF && - mds_mitigation == MDS_MITIGATION_OFF) - goto out; + if (taa_mitigation != TAA_MITIGATION_OFF) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init taa_update_mitigation(void) +{ + if (!taa_vulnerable()) + return; - if (boot_cpu_has(X86_FEATURE_MD_CLEAR)) + if (verw_clear_cpu_buf_mitigation_selected) taa_mitigation = TAA_MITIGATION_VERW; - else - taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; - /* - * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1. - * A microcode update fixes this behavior to clear CPU buffers. It also - * adds support for MSR_IA32_TSX_CTRL which is enumerated by the - * ARCH_CAP_TSX_CTRL_MSR bit. - * - * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode - * update is required. - */ - ia32_cap = x86_read_arch_cap_msr(); - if ( (ia32_cap & ARCH_CAP_MDS_NO) && - !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR)) - taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; + if (taa_mitigation == TAA_MITIGATION_VERW) { + /* Check if the requisite ucode is available. */ + if (!boot_cpu_has(X86_FEATURE_MD_CLEAR)) + taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; - /* - * TSX is enabled, select alternate mitigation for TAA which is - * the same as MDS. Enable MDS static branch to clear CPU buffers. - * - * For guests that can't determine whether the correct microcode is - * present on host, enable the mitigation for UCODE_NEEDED as well. - */ - static_branch_enable(&mds_user_clear); + /* + * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1. + * A microcode update fixes this behavior to clear CPU buffers. It also + * adds support for MSR_IA32_TSX_CTRL which is enumerated by the + * ARCH_CAP_TSX_CTRL_MSR bit. + * + * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode + * update is required. + */ + if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && + !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR)) + taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; + } - if (taa_nosmt || cpu_mitigations_auto_nosmt()) - cpu_smt_disable(false); + pr_info("%s\n", taa_strings[taa_mitigation]); +} - /* - * Update MDS mitigation, if necessary, as the mds_user_clear is - * now enabled for TAA mitigation. - */ - if (mds_mitigation == MDS_MITIGATION_OFF && - boot_cpu_has_bug(X86_BUG_MDS)) { - mds_mitigation = MDS_MITIGATION_FULL; - mds_select_mitigation(); +static void __init taa_apply_mitigation(void) +{ + if (taa_mitigation == TAA_MITIGATION_VERW || + taa_mitigation == TAA_MITIGATION_UCODE_NEEDED) { + /* + * TSX is enabled, select alternate mitigation for TAA which is + * the same as MDS. Enable MDS static branch to clear CPU buffers. + * + * For guests that can't determine whether the correct microcode is + * present on host, enable the mitigation for UCODE_NEEDED as well. + */ + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + + if (taa_nosmt || smt_mitigations == SMT_MITIGATIONS_ON) + cpu_smt_disable(false); } -out: - pr_info("%s\n", taa_strings[taa_mitigation]); } static int __init tsx_async_abort_parse_cmdline(char *str) @@ -401,17 +529,207 @@ static int __init tsx_async_abort_parse_cmdline(char *str) early_param("tsx_async_abort", tsx_async_abort_parse_cmdline); #undef pr_fmt +#define pr_fmt(fmt) "MMIO Stale Data: " fmt + +static bool mmio_nosmt __ro_after_init = false; + +static const char * const mmio_strings[] = { + [MMIO_MITIGATION_OFF] = "Vulnerable", + [MMIO_MITIGATION_UCODE_NEEDED] = "Vulnerable: Clear CPU buffers attempted, no microcode", + [MMIO_MITIGATION_VERW] = "Mitigation: Clear CPU buffers", +}; + +static void __init mmio_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) { + mmio_mitigation = MMIO_MITIGATION_OFF; + return; + } + + /* Microcode will be checked in mmio_update_mitigation(). */ + if (mmio_mitigation == MMIO_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_MMIO_STALE_DATA)) + mmio_mitigation = MMIO_MITIGATION_VERW; + else + mmio_mitigation = MMIO_MITIGATION_OFF; + } + + if (mmio_mitigation == MMIO_MITIGATION_OFF) + return; + + /* + * Enable CPU buffer clear mitigation for host and VMM, if also affected + * by MDS or TAA. + */ + if (boot_cpu_has_bug(X86_BUG_MDS) || taa_vulnerable()) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init mmio_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) + return; + + if (verw_clear_cpu_buf_mitigation_selected) + mmio_mitigation = MMIO_MITIGATION_VERW; + + if (mmio_mitigation == MMIO_MITIGATION_VERW) { + /* + * Check if the system has the right microcode. + * + * CPU Fill buffer clear mitigation is enumerated by either an explicit + * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS + * affected systems. + */ + if (!((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) || + (boot_cpu_has(X86_FEATURE_MD_CLEAR) && + boot_cpu_has(X86_FEATURE_FLUSH_L1D) && + !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)))) + mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED; + } + + pr_info("%s\n", mmio_strings[mmio_mitigation]); +} + +static void __init mmio_apply_mitigation(void) +{ + if (mmio_mitigation == MMIO_MITIGATION_OFF) + return; + + /* + * Only enable the VMM mitigation if the CPU buffer clear mitigation is + * not being used. + */ + if (verw_clear_cpu_buf_mitigation_selected) { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + } else { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM_MMIO); + } + + /* + * If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can + * be propagated to uncore buffers, clearing the Fill buffers on idle + * is required irrespective of SMT state. + */ + if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) + static_branch_enable(&cpu_buf_idle_clear); + + if (mmio_nosmt || smt_mitigations == SMT_MITIGATIONS_ON) + cpu_smt_disable(false); +} + +static int __init mmio_stale_data_parse_cmdline(char *str) +{ + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) + return 0; + + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) { + mmio_mitigation = MMIO_MITIGATION_OFF; + } else if (!strcmp(str, "full")) { + mmio_mitigation = MMIO_MITIGATION_VERW; + } else if (!strcmp(str, "full,nosmt")) { + mmio_mitigation = MMIO_MITIGATION_VERW; + mmio_nosmt = true; + } + + return 0; +} +early_param("mmio_stale_data", mmio_stale_data_parse_cmdline); + +#undef pr_fmt +#define pr_fmt(fmt) "Register File Data Sampling: " fmt + +static const char * const rfds_strings[] = { + [RFDS_MITIGATION_OFF] = "Vulnerable", + [RFDS_MITIGATION_VERW] = "Mitigation: Clear Register File", + [RFDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", +}; + +static inline bool __init verw_clears_cpu_reg_file(void) +{ + return (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR); +} + +static void __init rfds_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RFDS)) { + rfds_mitigation = RFDS_MITIGATION_OFF; + return; + } + + if (rfds_mitigation == RFDS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_RFDS)) + rfds_mitigation = RFDS_MITIGATION_VERW; + else + rfds_mitigation = RFDS_MITIGATION_OFF; + } + + if (rfds_mitigation == RFDS_MITIGATION_OFF) + return; + + if (verw_clears_cpu_reg_file()) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init rfds_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RFDS)) + return; + + if (verw_clear_cpu_buf_mitigation_selected) + rfds_mitigation = RFDS_MITIGATION_VERW; + + if (rfds_mitigation == RFDS_MITIGATION_VERW) { + if (!verw_clears_cpu_reg_file()) + rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED; + } + + pr_info("%s\n", rfds_strings[rfds_mitigation]); +} + +static void __init rfds_apply_mitigation(void) +{ + if (rfds_mitigation == RFDS_MITIGATION_VERW) { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + } +} + +static __init int rfds_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!boot_cpu_has_bug(X86_BUG_RFDS)) + return 0; + + if (!strcmp(str, "off")) + rfds_mitigation = RFDS_MITIGATION_OFF; + else if (!strcmp(str, "on")) + rfds_mitigation = RFDS_MITIGATION_VERW; + + return 0; +} +early_param("reg_file_data_sampling", rfds_parse_cmdline); + +#undef pr_fmt #define pr_fmt(fmt) "SRBDS: " fmt enum srbds_mitigations { SRBDS_MITIGATION_OFF, + SRBDS_MITIGATION_AUTO, SRBDS_MITIGATION_UCODE_NEEDED, SRBDS_MITIGATION_FULL, SRBDS_MITIGATION_TSX_OFF, SRBDS_MITIGATION_HYPERVISOR, }; -static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL; +static enum srbds_mitigations srbds_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SRBDS) ? SRBDS_MITIGATION_AUTO : SRBDS_MITIGATION_OFF; static const char * const srbds_strings[] = { [SRBDS_MITIGATION_OFF] = "Vulnerable", @@ -436,7 +754,14 @@ void update_srbds_msr(void) if (srbds_mitigation == SRBDS_MITIGATION_UCODE_NEEDED) return; - rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + /* + * A MDS_NO CPU for which SRBDS mitigation is not needed due to TSX + * being disabled and it hasn't received the SRBDS MSR microcode. + */ + if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL)) + return; + + rdmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); switch (srbds_mitigation) { case SRBDS_MITIGATION_OFF: @@ -450,34 +775,48 @@ void update_srbds_msr(void) break; } - wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + wrmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); } static void __init srbds_select_mitigation(void) { - u64 ia32_cap; - - if (!boot_cpu_has_bug(X86_BUG_SRBDS)) + if (!boot_cpu_has_bug(X86_BUG_SRBDS)) { + srbds_mitigation = SRBDS_MITIGATION_OFF; return; + } + + if (srbds_mitigation == SRBDS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_SRBDS)) + srbds_mitigation = SRBDS_MITIGATION_FULL; + else { + srbds_mitigation = SRBDS_MITIGATION_OFF; + return; + } + } /* - * Check to see if this is one of the MDS_NO systems supporting - * TSX that are only exposed to SRBDS when TSX is enabled. + * Check to see if this is one of the MDS_NO systems supporting TSX that + * are only exposed to SRBDS when TSX is enabled or when CPU is affected + * by Processor MMIO Stale Data vulnerability. */ - ia32_cap = x86_read_arch_cap_msr(); - if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM)) + if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) && + !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) srbds_mitigation = SRBDS_MITIGATION_TSX_OFF; else if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR; else if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL)) srbds_mitigation = SRBDS_MITIGATION_UCODE_NEEDED; - else if (cpu_mitigations_off() || srbds_off) + else if (srbds_off) srbds_mitigation = SRBDS_MITIGATION_OFF; - update_srbds_msr(); pr_info("%s\n", srbds_strings[srbds_mitigation]); } +static void __init srbds_apply_mitigation(void) +{ + update_srbds_msr(); +} + static int __init srbds_parse_cmdline(char *str) { if (!str) @@ -492,6 +831,188 @@ static int __init srbds_parse_cmdline(char *str) early_param("srbds", srbds_parse_cmdline); #undef pr_fmt +#define pr_fmt(fmt) "L1D Flush : " fmt + +enum l1d_flush_mitigations { + L1D_FLUSH_OFF = 0, + L1D_FLUSH_ON, +}; + +static enum l1d_flush_mitigations l1d_flush_mitigation __initdata = L1D_FLUSH_OFF; + +static void __init l1d_flush_select_mitigation(void) +{ + if (!l1d_flush_mitigation || !boot_cpu_has(X86_FEATURE_FLUSH_L1D)) + return; + + static_branch_enable(&switch_mm_cond_l1d_flush); + pr_info("Conditional flush on switch_mm() enabled\n"); +} + +static int __init l1d_flush_parse_cmdline(char *str) +{ + if (!strcmp(str, "on")) + l1d_flush_mitigation = L1D_FLUSH_ON; + + return 0; +} +early_param("l1d_flush", l1d_flush_parse_cmdline); + +#undef pr_fmt +#define pr_fmt(fmt) "GDS: " fmt + +enum gds_mitigations { + GDS_MITIGATION_OFF, + GDS_MITIGATION_AUTO, + GDS_MITIGATION_UCODE_NEEDED, + GDS_MITIGATION_FORCE, + GDS_MITIGATION_FULL, + GDS_MITIGATION_FULL_LOCKED, + GDS_MITIGATION_HYPERVISOR, +}; + +static enum gds_mitigations gds_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_GDS) ? GDS_MITIGATION_AUTO : GDS_MITIGATION_OFF; + +static const char * const gds_strings[] = { + [GDS_MITIGATION_OFF] = "Vulnerable", + [GDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", + [GDS_MITIGATION_FORCE] = "Mitigation: AVX disabled, no microcode", + [GDS_MITIGATION_FULL] = "Mitigation: Microcode", + [GDS_MITIGATION_FULL_LOCKED] = "Mitigation: Microcode (locked)", + [GDS_MITIGATION_HYPERVISOR] = "Unknown: Dependent on hypervisor status", +}; + +bool gds_ucode_mitigated(void) +{ + return (gds_mitigation == GDS_MITIGATION_FULL || + gds_mitigation == GDS_MITIGATION_FULL_LOCKED); +} +EXPORT_SYMBOL_FOR_KVM(gds_ucode_mitigated); + +void update_gds_msr(void) +{ + u64 mcu_ctrl_after; + u64 mcu_ctrl; + + switch (gds_mitigation) { + case GDS_MITIGATION_OFF: + rdmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + mcu_ctrl |= GDS_MITG_DIS; + break; + case GDS_MITIGATION_FULL_LOCKED: + /* + * The LOCKED state comes from the boot CPU. APs might not have + * the same state. Make sure the mitigation is enabled on all + * CPUs. + */ + case GDS_MITIGATION_FULL: + rdmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + mcu_ctrl &= ~GDS_MITG_DIS; + break; + case GDS_MITIGATION_FORCE: + case GDS_MITIGATION_UCODE_NEEDED: + case GDS_MITIGATION_HYPERVISOR: + case GDS_MITIGATION_AUTO: + return; + } + + wrmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + + /* + * Check to make sure that the WRMSR value was not ignored. Writes to + * GDS_MITG_DIS will be ignored if this processor is locked but the boot + * processor was not. + */ + rdmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl_after); + WARN_ON_ONCE(mcu_ctrl != mcu_ctrl_after); +} + +static void __init gds_select_mitigation(void) +{ + u64 mcu_ctrl; + + if (!boot_cpu_has_bug(X86_BUG_GDS)) + return; + + if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { + gds_mitigation = GDS_MITIGATION_HYPERVISOR; + return; + } + + /* Will verify below that mitigation _can_ be disabled */ + if (gds_mitigation == GDS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_GDS)) + gds_mitigation = GDS_MITIGATION_FULL; + else + gds_mitigation = GDS_MITIGATION_OFF; + } + + /* No microcode */ + if (!(x86_arch_cap_msr & ARCH_CAP_GDS_CTRL)) { + if (gds_mitigation != GDS_MITIGATION_FORCE) + gds_mitigation = GDS_MITIGATION_UCODE_NEEDED; + return; + } + + /* Microcode has mitigation, use it */ + if (gds_mitigation == GDS_MITIGATION_FORCE) + gds_mitigation = GDS_MITIGATION_FULL; + + rdmsrq(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl); + if (mcu_ctrl & GDS_MITG_LOCKED) { + if (gds_mitigation == GDS_MITIGATION_OFF) + pr_warn("Mitigation locked. Disable failed.\n"); + + /* + * The mitigation is selected from the boot CPU. All other CPUs + * _should_ have the same state. If the boot CPU isn't locked + * but others are then update_gds_msr() will WARN() of the state + * mismatch. If the boot CPU is locked update_gds_msr() will + * ensure the other CPUs have the mitigation enabled. + */ + gds_mitigation = GDS_MITIGATION_FULL_LOCKED; + } +} + +static void __init gds_apply_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_GDS)) + return; + + /* Microcode is present */ + if (x86_arch_cap_msr & ARCH_CAP_GDS_CTRL) + update_gds_msr(); + else if (gds_mitigation == GDS_MITIGATION_FORCE) { + /* + * This only needs to be done on the boot CPU so do it + * here rather than in update_gds_msr() + */ + setup_clear_cpu_cap(X86_FEATURE_AVX); + pr_warn("Microcode update needed! Disabling AVX as mitigation.\n"); + } + + pr_info("%s\n", gds_strings[gds_mitigation]); +} + +static int __init gds_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!boot_cpu_has_bug(X86_BUG_GDS)) + return 0; + + if (!strcmp(str, "off")) + gds_mitigation = GDS_MITIGATION_OFF; + else if (!strcmp(str, "force")) + gds_mitigation = GDS_MITIGATION_FORCE; + + return 0; +} +early_param("gather_data_sampling", gds_parse_cmdline); + +#undef pr_fmt #define pr_fmt(fmt) "Spectre V1 : " fmt enum spectre_v1_mitigation { @@ -500,7 +1021,8 @@ enum spectre_v1_mitigation { }; static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init = - SPECTRE_V1_MITIGATION_AUTO; + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V1) ? + SPECTRE_V1_MITIGATION_AUTO : SPECTRE_V1_MITIGATION_NONE; static const char * const spectre_v1_strings[] = { [SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers", @@ -530,10 +1052,17 @@ static bool smap_works_speculatively(void) static void __init spectre_v1_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1)) spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE; + + if (!should_mitigate_vuln(X86_BUG_SPECTRE_V1)) + spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE; +} + +static void __init spectre_v1_apply_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1)) return; - } if (spectre_v1_mitigation == SPECTRE_V1_MITIGATION_AUTO) { /* @@ -581,18 +1110,532 @@ static int __init nospectre_v1_cmdline(char *str) } early_param("nospectre_v1", nospectre_v1_cmdline); +enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE; + +/* Depends on spectre_v2 mitigation selected already */ +static inline bool cdt_possible(enum spectre_v2_mitigation mode) +{ + if (!IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) || + !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) + return false; + + if (mode == SPECTRE_V2_RETPOLINE || + mode == SPECTRE_V2_EIBRS_RETPOLINE) + return true; + + return false; +} + #undef pr_fmt -#define pr_fmt(fmt) "Spectre V2 : " fmt +#define pr_fmt(fmt) "RETBleed: " fmt + +enum its_mitigation { + ITS_MITIGATION_OFF, + ITS_MITIGATION_AUTO, + ITS_MITIGATION_VMEXIT_ONLY, + ITS_MITIGATION_ALIGNED_THUNKS, + ITS_MITIGATION_RETPOLINE_STUFF, +}; + +static enum its_mitigation its_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_ITS) ? ITS_MITIGATION_AUTO : ITS_MITIGATION_OFF; + +enum retbleed_mitigation { + RETBLEED_MITIGATION_NONE, + RETBLEED_MITIGATION_AUTO, + RETBLEED_MITIGATION_UNRET, + RETBLEED_MITIGATION_IBPB, + RETBLEED_MITIGATION_IBRS, + RETBLEED_MITIGATION_EIBRS, + RETBLEED_MITIGATION_STUFF, +}; + +static const char * const retbleed_strings[] = { + [RETBLEED_MITIGATION_NONE] = "Vulnerable", + [RETBLEED_MITIGATION_UNRET] = "Mitigation: untrained return thunk", + [RETBLEED_MITIGATION_IBPB] = "Mitigation: IBPB", + [RETBLEED_MITIGATION_IBRS] = "Mitigation: IBRS", + [RETBLEED_MITIGATION_EIBRS] = "Mitigation: Enhanced IBRS", + [RETBLEED_MITIGATION_STUFF] = "Mitigation: Stuffing", +}; + +static enum retbleed_mitigation retbleed_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_RETBLEED) ? RETBLEED_MITIGATION_AUTO : RETBLEED_MITIGATION_NONE; + +static int __ro_after_init retbleed_nosmt = false; + +enum srso_mitigation { + SRSO_MITIGATION_NONE, + SRSO_MITIGATION_AUTO, + SRSO_MITIGATION_UCODE_NEEDED, + SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED, + SRSO_MITIGATION_MICROCODE, + SRSO_MITIGATION_NOSMT, + SRSO_MITIGATION_SAFE_RET, + SRSO_MITIGATION_IBPB, + SRSO_MITIGATION_IBPB_ON_VMEXIT, + SRSO_MITIGATION_BP_SPEC_REDUCE, +}; + +static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_AUTO; + +static int __init retbleed_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + while (str) { + char *next = strchr(str, ','); + if (next) { + *next = 0; + next++; + } + + if (!strcmp(str, "off")) { + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } else if (!strcmp(str, "auto")) { + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } else if (!strcmp(str, "unret")) { + retbleed_mitigation = RETBLEED_MITIGATION_UNRET; + } else if (!strcmp(str, "ibpb")) { + retbleed_mitigation = RETBLEED_MITIGATION_IBPB; + } else if (!strcmp(str, "stuff")) { + retbleed_mitigation = RETBLEED_MITIGATION_STUFF; + } else if (!strcmp(str, "nosmt")) { + retbleed_nosmt = true; + } else if (!strcmp(str, "force")) { + setup_force_cpu_bug(X86_BUG_RETBLEED); + } else { + pr_err("Ignoring unknown retbleed option (%s).", str); + } + + str = next; + } + + return 0; +} +early_param("retbleed", retbleed_parse_cmdline); + +#define RETBLEED_UNTRAIN_MSG "WARNING: BTB untrained return thunk mitigation is only effective on AMD/Hygon!\n" +#define RETBLEED_INTEL_MSG "WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!\n" + +static void __init retbleed_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RETBLEED)) { + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + return; + } + + switch (retbleed_mitigation) { + case RETBLEED_MITIGATION_UNRET: + if (!IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) { + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + pr_err("WARNING: kernel not compiled with MITIGATION_UNRET_ENTRY.\n"); + } + break; + case RETBLEED_MITIGATION_IBPB: + if (!boot_cpu_has(X86_FEATURE_IBPB)) { + pr_err("WARNING: CPU does not support IBPB.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } else if (!IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { + pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } + break; + case RETBLEED_MITIGATION_STUFF: + if (!IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)) { + pr_err("WARNING: kernel not compiled with MITIGATION_CALL_DEPTH_TRACKING.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } else if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { + pr_err("WARNING: retbleed=stuff only supported for Intel CPUs.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } + break; + default: + break; + } + + if (retbleed_mitigation != RETBLEED_MITIGATION_AUTO) + return; + + if (!should_mitigate_vuln(X86_BUG_RETBLEED)) { + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + return; + } + + /* Intel mitigation selected in retbleed_update_mitigation() */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { + if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) + retbleed_mitigation = RETBLEED_MITIGATION_UNRET; + else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) && + boot_cpu_has(X86_FEATURE_IBPB)) + retbleed_mitigation = RETBLEED_MITIGATION_IBPB; + else + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } else if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + /* Final mitigation depends on spectre-v2 selection */ + if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) + retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; + else if (boot_cpu_has(X86_FEATURE_IBRS)) + retbleed_mitigation = RETBLEED_MITIGATION_IBRS; + else + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } +} + +static void __init retbleed_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RETBLEED)) + return; + + /* ITS can also enable stuffing */ + if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF) + retbleed_mitigation = RETBLEED_MITIGATION_STUFF; + + /* If SRSO is using IBPB, that works for retbleed too */ + if (srso_mitigation == SRSO_MITIGATION_IBPB) + retbleed_mitigation = RETBLEED_MITIGATION_IBPB; + + if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF && + !cdt_possible(spectre_v2_enabled)) { + pr_err("WARNING: retbleed=stuff depends on retpoline\n"); + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } + + /* + * Let IBRS trump all on Intel without affecting the effects of the + * retbleed= cmdline option except for call depth based stuffing + */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + switch (spectre_v2_enabled) { + case SPECTRE_V2_IBRS: + retbleed_mitigation = RETBLEED_MITIGATION_IBRS; + break; + case SPECTRE_V2_EIBRS: + case SPECTRE_V2_EIBRS_RETPOLINE: + case SPECTRE_V2_EIBRS_LFENCE: + retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; + break; + default: + if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) { + if (retbleed_mitigation != RETBLEED_MITIGATION_NONE) + pr_err(RETBLEED_INTEL_MSG); + + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } + } + } + + pr_info("%s\n", retbleed_strings[retbleed_mitigation]); +} + +static void __init retbleed_apply_mitigation(void) +{ + bool mitigate_smt = false; + + switch (retbleed_mitigation) { + case RETBLEED_MITIGATION_NONE: + return; + + case RETBLEED_MITIGATION_UNRET: + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_UNRET); -static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = - SPECTRE_V2_NONE; + set_return_thunk(retbleed_return_thunk); + + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && + boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) + pr_err(RETBLEED_UNTRAIN_MSG); + + mitigate_smt = true; + break; + + case RETBLEED_MITIGATION_IBPB: + setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB); + setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT); + mitigate_smt = true; + + /* + * IBPB on entry already obviates the need for + * software-based untraining so clear those in case some + * other mitigation like SRSO has selected them. + */ + setup_clear_cpu_cap(X86_FEATURE_UNRET); + setup_clear_cpu_cap(X86_FEATURE_RETHUNK); + + /* + * There is no need for RSB filling: write_ibpb() ensures + * all predictions, including the RSB, are invalidated, + * regardless of IBPB implementation. + */ + setup_clear_cpu_cap(X86_FEATURE_RSB_VMEXIT); + + break; + + case RETBLEED_MITIGATION_STUFF: + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); + + set_return_thunk(call_depth_return_thunk); + break; + + default: + break; + } + + if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) && + (retbleed_nosmt || smt_mitigations == SMT_MITIGATIONS_ON)) + cpu_smt_disable(false); +} + +#undef pr_fmt +#define pr_fmt(fmt) "ITS: " fmt + +static const char * const its_strings[] = { + [ITS_MITIGATION_OFF] = "Vulnerable", + [ITS_MITIGATION_VMEXIT_ONLY] = "Mitigation: Vulnerable, KVM: Not affected", + [ITS_MITIGATION_ALIGNED_THUNKS] = "Mitigation: Aligned branch/return thunks", + [ITS_MITIGATION_RETPOLINE_STUFF] = "Mitigation: Retpolines, Stuffing RSB", +}; + +static int __init its_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!IS_ENABLED(CONFIG_MITIGATION_ITS)) { + pr_err("Mitigation disabled at compile time, ignoring option (%s)", str); + return 0; + } + + if (!strcmp(str, "off")) { + its_mitigation = ITS_MITIGATION_OFF; + } else if (!strcmp(str, "on")) { + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; + } else if (!strcmp(str, "force")) { + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; + setup_force_cpu_bug(X86_BUG_ITS); + } else if (!strcmp(str, "vmexit")) { + its_mitigation = ITS_MITIGATION_VMEXIT_ONLY; + } else if (!strcmp(str, "stuff")) { + its_mitigation = ITS_MITIGATION_RETPOLINE_STUFF; + } else { + pr_err("Ignoring unknown indirect_target_selection option (%s).", str); + } + + return 0; +} +early_param("indirect_target_selection", its_parse_cmdline); + +static void __init its_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_ITS)) { + its_mitigation = ITS_MITIGATION_OFF; + return; + } + + if (its_mitigation == ITS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_ITS)) + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; + else + its_mitigation = ITS_MITIGATION_OFF; + } + + if (its_mitigation == ITS_MITIGATION_OFF) + return; + + if (!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) || + !IS_ENABLED(CONFIG_MITIGATION_RETHUNK)) { + pr_err("WARNING: ITS mitigation depends on retpoline and rethunk support\n"); + its_mitigation = ITS_MITIGATION_OFF; + return; + } + + if (IS_ENABLED(CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B)) { + pr_err("WARNING: ITS mitigation is not compatible with CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B\n"); + its_mitigation = ITS_MITIGATION_OFF; + return; + } + + if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF && + !IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)) { + pr_err("RSB stuff mitigation not supported, using default\n"); + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; + } + + if (its_mitigation == ITS_MITIGATION_VMEXIT_ONLY && + !boot_cpu_has_bug(X86_BUG_ITS_NATIVE_ONLY)) + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; +} + +static void __init its_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_ITS)) + return; + + switch (spectre_v2_enabled) { + case SPECTRE_V2_NONE: + if (its_mitigation != ITS_MITIGATION_OFF) + pr_err("WARNING: Spectre-v2 mitigation is off, disabling ITS\n"); + its_mitigation = ITS_MITIGATION_OFF; + break; + case SPECTRE_V2_RETPOLINE: + case SPECTRE_V2_EIBRS_RETPOLINE: + /* Retpoline+CDT mitigates ITS */ + if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF) + its_mitigation = ITS_MITIGATION_RETPOLINE_STUFF; + break; + case SPECTRE_V2_LFENCE: + case SPECTRE_V2_EIBRS_LFENCE: + pr_err("WARNING: ITS mitigation is not compatible with lfence mitigation\n"); + its_mitigation = ITS_MITIGATION_OFF; + break; + default: + break; + } + + if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF && + !cdt_possible(spectre_v2_enabled)) + its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS; + + pr_info("%s\n", its_strings[its_mitigation]); +} + +static void __init its_apply_mitigation(void) +{ + switch (its_mitigation) { + case ITS_MITIGATION_OFF: + case ITS_MITIGATION_AUTO: + case ITS_MITIGATION_VMEXIT_ONLY: + break; + case ITS_MITIGATION_ALIGNED_THUNKS: + if (!boot_cpu_has(X86_FEATURE_RETPOLINE)) + setup_force_cpu_cap(X86_FEATURE_INDIRECT_THUNK_ITS); + + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + set_return_thunk(its_return_thunk); + break; + case ITS_MITIGATION_RETPOLINE_STUFF: + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); + set_return_thunk(call_depth_return_thunk); + break; + } +} + +#undef pr_fmt +#define pr_fmt(fmt) "Transient Scheduler Attacks: " fmt + +enum tsa_mitigations { + TSA_MITIGATION_NONE, + TSA_MITIGATION_AUTO, + TSA_MITIGATION_UCODE_NEEDED, + TSA_MITIGATION_USER_KERNEL, + TSA_MITIGATION_VM, + TSA_MITIGATION_FULL, +}; + +static const char * const tsa_strings[] = { + [TSA_MITIGATION_NONE] = "Vulnerable", + [TSA_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", + [TSA_MITIGATION_USER_KERNEL] = "Mitigation: Clear CPU buffers: user/kernel boundary", + [TSA_MITIGATION_VM] = "Mitigation: Clear CPU buffers: VM", + [TSA_MITIGATION_FULL] = "Mitigation: Clear CPU buffers", +}; + +static enum tsa_mitigations tsa_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_TSA) ? TSA_MITIGATION_AUTO : TSA_MITIGATION_NONE; + +static int __init tsa_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) + tsa_mitigation = TSA_MITIGATION_NONE; + else if (!strcmp(str, "on")) + tsa_mitigation = TSA_MITIGATION_FULL; + else if (!strcmp(str, "user")) + tsa_mitigation = TSA_MITIGATION_USER_KERNEL; + else if (!strcmp(str, "vm")) + tsa_mitigation = TSA_MITIGATION_VM; + else + pr_err("Ignoring unknown tsa=%s option.\n", str); + + return 0; +} +early_param("tsa", tsa_parse_cmdline); + +static void __init tsa_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_TSA)) { + tsa_mitigation = TSA_MITIGATION_NONE; + return; + } + + if (tsa_mitigation == TSA_MITIGATION_AUTO) { + bool vm = false, uk = false; + + tsa_mitigation = TSA_MITIGATION_NONE; + + if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) || + cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER)) { + tsa_mitigation = TSA_MITIGATION_USER_KERNEL; + uk = true; + } + + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST)) { + tsa_mitigation = TSA_MITIGATION_VM; + vm = true; + } + + if (uk && vm) + tsa_mitigation = TSA_MITIGATION_FULL; + } + + if (tsa_mitigation == TSA_MITIGATION_NONE) + return; + + if (!boot_cpu_has(X86_FEATURE_VERW_CLEAR)) + tsa_mitigation = TSA_MITIGATION_UCODE_NEEDED; + + /* + * No need to set verw_clear_cpu_buf_mitigation_selected - it + * doesn't fit all cases here and it is not needed because this + * is the only VERW-based mitigation on AMD. + */ + pr_info("%s\n", tsa_strings[tsa_mitigation]); +} + +static void __init tsa_apply_mitigation(void) +{ + switch (tsa_mitigation) { + case TSA_MITIGATION_USER_KERNEL: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + break; + case TSA_MITIGATION_VM: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + break; + case TSA_MITIGATION_FULL: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + break; + default: + break; + } +} + +#undef pr_fmt +#define pr_fmt(fmt) "Spectre V2 : " fmt static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init = SPECTRE_V2_USER_NONE; static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init = SPECTRE_V2_USER_NONE; -#ifdef CONFIG_RETPOLINE +#ifdef CONFIG_MITIGATION_RETPOLINE static bool spectre_v2_bad_module; bool retpoline_module_ok(bool has_retpoline) @@ -613,12 +1656,32 @@ static inline const char *spectre_v2_module_string(void) static inline const char *spectre_v2_module_string(void) { return ""; } #endif -static inline bool match_option(const char *arg, int arglen, const char *opt) +#define SPECTRE_V2_LFENCE_MSG "WARNING: LFENCE mitigation is not recommended for this CPU, data leaks possible!\n" +#define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" +#define SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS+LFENCE mitigation and SMT, data leaks possible via Spectre v2 BHB attacks!\n" +#define SPECTRE_V2_IBRS_PERF_MSG "WARNING: IBRS mitigation selected on Enhanced IBRS CPU, this may cause unnecessary performance loss\n" + +#ifdef CONFIG_BPF_SYSCALL +void unpriv_ebpf_notify(int new_state) { - int len = strlen(opt); + if (new_state) + return; + + /* Unprivileged eBPF is enabled */ - return len == arglen && !strncmp(arg, opt, len); + switch (spectre_v2_enabled) { + case SPECTRE_V2_EIBRS: + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); + break; + case SPECTRE_V2_EIBRS_LFENCE: + if (sched_smt_active()) + pr_err(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG); + break; + default: + break; + } } +#endif /* The kernel command line selection for spectre v2 */ enum spectre_v2_mitigation_cmd { @@ -627,10 +1690,17 @@ enum spectre_v2_mitigation_cmd { SPECTRE_V2_CMD_FORCE, SPECTRE_V2_CMD_RETPOLINE, SPECTRE_V2_CMD_RETPOLINE_GENERIC, - SPECTRE_V2_CMD_RETPOLINE_AMD, + SPECTRE_V2_CMD_RETPOLINE_LFENCE, + SPECTRE_V2_CMD_EIBRS, + SPECTRE_V2_CMD_EIBRS_RETPOLINE, + SPECTRE_V2_CMD_EIBRS_LFENCE, + SPECTRE_V2_CMD_IBRS, }; -enum spectre_v2_user_cmd { +static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE; + +enum spectre_v2_user_mitigation_cmd { SPECTRE_V2_USER_CMD_NONE, SPECTRE_V2_USER_CMD_AUTO, SPECTRE_V2_USER_CMD_FORCE, @@ -640,6 +1710,9 @@ enum spectre_v2_user_cmd { SPECTRE_V2_USER_CMD_SECCOMP_IBPB, }; +static enum spectre_v2_user_mitigation_cmd spectre_v2_user_cmd __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE; + static const char * const spectre_v2_user_strings[] = { [SPECTRE_V2_USER_NONE] = "User space: Vulnerable", [SPECTRE_V2_USER_STRICT] = "User space: Mitigation: STIBP protection", @@ -648,108 +1721,155 @@ static const char * const spectre_v2_user_strings[] = { [SPECTRE_V2_USER_SECCOMP] = "User space: Mitigation: STIBP via seccomp and prctl", }; -static const struct { - const char *option; - enum spectre_v2_user_cmd cmd; - bool secure; -} v2_user_options[] __initconst = { - { "auto", SPECTRE_V2_USER_CMD_AUTO, false }, - { "off", SPECTRE_V2_USER_CMD_NONE, false }, - { "on", SPECTRE_V2_USER_CMD_FORCE, true }, - { "prctl", SPECTRE_V2_USER_CMD_PRCTL, false }, - { "prctl,ibpb", SPECTRE_V2_USER_CMD_PRCTL_IBPB, false }, - { "seccomp", SPECTRE_V2_USER_CMD_SECCOMP, false }, - { "seccomp,ibpb", SPECTRE_V2_USER_CMD_SECCOMP_IBPB, false }, -}; - -static void __init spec_v2_user_print_cond(const char *reason, bool secure) -{ - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure) - pr_info("spectre_v2_user=%s forced on command line.\n", reason); -} - -static enum spectre_v2_user_cmd __init -spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd) +static int __init spectre_v2_user_parse_cmdline(char *str) { - char arg[20]; - int ret, i; - - switch (v2_cmd) { - case SPECTRE_V2_CMD_NONE: - return SPECTRE_V2_USER_CMD_NONE; - case SPECTRE_V2_CMD_FORCE: - return SPECTRE_V2_USER_CMD_FORCE; - default: - break; - } - - ret = cmdline_find_option(boot_command_line, "spectre_v2_user", - arg, sizeof(arg)); - if (ret < 0) - return SPECTRE_V2_USER_CMD_AUTO; + if (!str) + return -EINVAL; - for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { - if (match_option(arg, ret, v2_user_options[i].option)) { - spec_v2_user_print_cond(v2_user_options[i].option, - v2_user_options[i].secure); - return v2_user_options[i].cmd; - } - } + if (!strcmp(str, "auto")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_AUTO; + else if (!strcmp(str, "off")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_NONE; + else if (!strcmp(str, "on")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_FORCE; + else if (!strcmp(str, "prctl")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL; + else if (!strcmp(str, "prctl,ibpb")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL_IBPB; + else if (!strcmp(str, "seccomp")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP; + else if (!strcmp(str, "seccomp,ibpb")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP_IBPB; + else + pr_err("Ignoring unknown spectre_v2_user option (%s).", str); - pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg); - return SPECTRE_V2_USER_CMD_AUTO; + return 0; } +early_param("spectre_v2_user", spectre_v2_user_parse_cmdline); -static void __init -spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) +static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) { - enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE; - bool smt_possible = IS_ENABLED(CONFIG_SMP); - enum spectre_v2_user_cmd cmd; + return spectre_v2_in_eibrs_mode(mode) || mode == SPECTRE_V2_IBRS; +} +static void __init spectre_v2_user_select_mitigation(void) +{ if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) return; - if (cpu_smt_control == CPU_SMT_FORCE_DISABLED || - cpu_smt_control == CPU_SMT_NOT_SUPPORTED) - smt_possible = false; - - cmd = spectre_v2_parse_user_cmdline(v2_cmd); - switch (cmd) { + switch (spectre_v2_user_cmd) { case SPECTRE_V2_USER_CMD_NONE: - goto set_mode; + return; case SPECTRE_V2_USER_CMD_FORCE: - mode = SPECTRE_V2_USER_STRICT; + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT; + break; + case SPECTRE_V2_USER_CMD_AUTO: + if (!should_mitigate_vuln(X86_BUG_SPECTRE_V2_USER)) + break; + spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL; + if (smt_mitigations == SMT_MITIGATIONS_OFF) + break; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; break; case SPECTRE_V2_USER_CMD_PRCTL: + spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; + break; case SPECTRE_V2_USER_CMD_PRCTL_IBPB: - mode = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; break; - case SPECTRE_V2_USER_CMD_AUTO: case SPECTRE_V2_USER_CMD_SECCOMP: + if (IS_ENABLED(CONFIG_SECCOMP)) + spectre_v2_user_ibpb = SPECTRE_V2_USER_SECCOMP; + else + spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = spectre_v2_user_ibpb; + break; case SPECTRE_V2_USER_CMD_SECCOMP_IBPB: + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; if (IS_ENABLED(CONFIG_SECCOMP)) - mode = SPECTRE_V2_USER_SECCOMP; + spectre_v2_user_stibp = SPECTRE_V2_USER_SECCOMP; else - mode = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; break; } + /* + * At this point, an STIBP mode other than "off" has been set. + * If STIBP support is not being forced, check if STIBP always-on + * is preferred. + */ + if ((spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL || + spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP) && + boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT_PREFERRED; + + if (!boot_cpu_has(X86_FEATURE_IBPB)) + spectre_v2_user_ibpb = SPECTRE_V2_USER_NONE; + + if (!boot_cpu_has(X86_FEATURE_STIBP)) + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; +} + +static void __init spectre_v2_user_update_mitigation(void) +{ + if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) + return; + + /* The spectre_v2 cmd line can override spectre_v2_user options */ + if (spectre_v2_cmd == SPECTRE_V2_CMD_NONE) { + spectre_v2_user_ibpb = SPECTRE_V2_USER_NONE; + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; + } else if (spectre_v2_cmd == SPECTRE_V2_CMD_FORCE) { + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT; + } + + /* + * If no STIBP, Intel enhanced IBRS is enabled, or SMT impossible, STIBP + * is not required. + * + * Intel's Enhanced IBRS also protects against cross-thread branch target + * injection in user-mode as the IBRS bit remains always set which + * implicitly enables cross-thread protections. However, in legacy IBRS + * mode, the IBRS bit is set only on kernel entry and cleared on return + * to userspace. AMD Automatic IBRS also does not protect userspace. + * These modes therefore disable the implicit cross-thread protection, + * so allow for STIBP to be selected in those cases. + */ + if (!boot_cpu_has(X86_FEATURE_STIBP) || + !cpu_smt_possible() || + (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && + !boot_cpu_has(X86_FEATURE_AUTOIBRS))) { + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; + return; + } + + if (spectre_v2_user_stibp != SPECTRE_V2_USER_NONE && + (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || + retbleed_mitigation == RETBLEED_MITIGATION_IBPB)) { + if (spectre_v2_user_stibp != SPECTRE_V2_USER_STRICT && + spectre_v2_user_stibp != SPECTRE_V2_USER_STRICT_PREFERRED) + pr_info("Selecting STIBP always-on mode to complement retbleed mitigation\n"); + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT_PREFERRED; + } + pr_info("%s\n", spectre_v2_user_strings[spectre_v2_user_stibp]); +} + +static void __init spectre_v2_user_apply_mitigation(void) +{ /* Initialize Indirect Branch Prediction Barrier */ - if (boot_cpu_has(X86_FEATURE_IBPB)) { - setup_force_cpu_cap(X86_FEATURE_USE_IBPB); + if (spectre_v2_user_ibpb != SPECTRE_V2_USER_NONE) { + static_branch_enable(&switch_vcpu_ibpb); - spectre_v2_user_ibpb = mode; - switch (cmd) { - case SPECTRE_V2_USER_CMD_FORCE: - case SPECTRE_V2_USER_CMD_PRCTL_IBPB: - case SPECTRE_V2_USER_CMD_SECCOMP_IBPB: + switch (spectre_v2_user_ibpb) { + case SPECTRE_V2_USER_STRICT: static_branch_enable(&switch_mm_always_ibpb); - spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; break; - case SPECTRE_V2_USER_CMD_PRCTL: - case SPECTRE_V2_USER_CMD_AUTO: - case SPECTRE_V2_USER_CMD_SECCOMP: + case SPECTRE_V2_USER_PRCTL: + case SPECTRE_V2_USER_SECCOMP: static_branch_enable(&switch_mm_cond_ibpb); break; default: @@ -760,203 +1880,447 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) static_key_enabled(&switch_mm_always_ibpb) ? "always-on" : "conditional"); } +} - /* - * If no STIBP, enhanced IBRS is enabled or SMT impossible, STIBP is not - * required. - */ - if (!boot_cpu_has(X86_FEATURE_STIBP) || - !smt_possible || - spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) +static const char * const spectre_v2_strings[] = { + [SPECTRE_V2_NONE] = "Vulnerable", + [SPECTRE_V2_RETPOLINE] = "Mitigation: Retpolines", + [SPECTRE_V2_LFENCE] = "Vulnerable: LFENCE", + [SPECTRE_V2_EIBRS] = "Mitigation: Enhanced / Automatic IBRS", + [SPECTRE_V2_EIBRS_LFENCE] = "Mitigation: Enhanced / Automatic IBRS + LFENCE", + [SPECTRE_V2_EIBRS_RETPOLINE] = "Mitigation: Enhanced / Automatic IBRS + Retpolines", + [SPECTRE_V2_IBRS] = "Mitigation: IBRS", +}; + +static bool nospectre_v2 __ro_after_init; + +static int __init nospectre_v2_parse_cmdline(char *str) +{ + nospectre_v2 = true; + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; + return 0; +} +early_param("nospectre_v2", nospectre_v2_parse_cmdline); + +static int __init spectre_v2_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (nospectre_v2) + return 0; + + if (!strcmp(str, "off")) { + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; + } else if (!strcmp(str, "on")) { + spectre_v2_cmd = SPECTRE_V2_CMD_FORCE; + setup_force_cpu_bug(X86_BUG_SPECTRE_V2); + setup_force_cpu_bug(X86_BUG_SPECTRE_V2_USER); + } else if (!strcmp(str, "retpoline")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE; + } else if (!strcmp(str, "retpoline,amd") || + !strcmp(str, "retpoline,lfence")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_LFENCE; + } else if (!strcmp(str, "retpoline,generic")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_GENERIC; + } else if (!strcmp(str, "eibrs")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS; + } else if (!strcmp(str, "eibrs,lfence")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_LFENCE; + } else if (!strcmp(str, "eibrs,retpoline")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_RETPOLINE; + } else if (!strcmp(str, "auto")) { + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } else if (!strcmp(str, "ibrs")) { + spectre_v2_cmd = SPECTRE_V2_CMD_IBRS; + } else { + pr_err("Ignoring unknown spectre_v2 option (%s).", str); + } + + return 0; +} +early_param("spectre_v2", spectre_v2_parse_cmdline); + +static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void) +{ + if (!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) { + pr_err("Kernel not compiled with retpoline; no mitigation available!"); + return SPECTRE_V2_NONE; + } + + return SPECTRE_V2_RETPOLINE; +} + +static bool __ro_after_init rrsba_disabled; + +/* Disable in-kernel use of non-RSB RET predictors */ +static void __init spec_ctrl_disable_kernel_rrsba(void) +{ + if (rrsba_disabled) + return; + + if (!(x86_arch_cap_msr & ARCH_CAP_RRSBA)) { + rrsba_disabled = true; + return; + } + + if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL)) return; + x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S; + update_spec_ctrl(x86_spec_ctrl_base); + rrsba_disabled = true; +} + +static void __init spectre_v2_select_rsb_mitigation(enum spectre_v2_mitigation mode) +{ /* - * At this point, an STIBP mode other than "off" has been set. - * If STIBP support is not being forced, check if STIBP always-on - * is preferred. + * WARNING! There are many subtleties to consider when changing *any* + * code related to RSB-related mitigations. Before doing so, carefully + * read the following document, and update if necessary: + * + * Documentation/admin-guide/hw-vuln/rsb.rst + * + * In an overly simplified nutshell: + * + * - User->user RSB attacks are conditionally mitigated during + * context switches by cond_mitigation -> write_ibpb(). + * + * - User->kernel and guest->host attacks are mitigated by eIBRS or + * RSB filling. + * + * Though, depending on config, note that other alternative + * mitigations may end up getting used instead, e.g., IBPB on + * entry/vmexit, call depth tracking, or return thunks. */ - if (mode != SPECTRE_V2_USER_STRICT && - boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) - mode = SPECTRE_V2_USER_STRICT_PREFERRED; - spectre_v2_user_stibp = mode; + switch (mode) { + case SPECTRE_V2_NONE: + break; + + case SPECTRE_V2_EIBRS: + case SPECTRE_V2_EIBRS_LFENCE: + case SPECTRE_V2_EIBRS_RETPOLINE: + if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) { + pr_info("Spectre v2 / PBRSB-eIBRS: Retire a single CALL on VMEXIT\n"); + setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE); + } + break; + + case SPECTRE_V2_RETPOLINE: + case SPECTRE_V2_LFENCE: + case SPECTRE_V2_IBRS: + pr_info("Spectre v2 / SpectreRSB: Filling RSB on context switch and VMEXIT\n"); + setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW); + setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT); + break; + + default: + pr_warn_once("Unknown Spectre v2 mode, disabling RSB mitigation\n"); + dump_stack(); + break; + } +} + +/* + * Set BHI_DIS_S to prevent indirect branches in kernel to be influenced by + * branch history in userspace. Not needed if BHI_NO is set. + */ +static bool __init spec_ctrl_bhi_dis(void) +{ + if (!boot_cpu_has(X86_FEATURE_BHI_CTRL)) + return false; + + x86_spec_ctrl_base |= SPEC_CTRL_BHI_DIS_S; + update_spec_ctrl(x86_spec_ctrl_base); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_HW); -set_mode: - pr_info("%s\n", spectre_v2_user_strings[mode]); + return true; } -static const char * const spectre_v2_strings[] = { - [SPECTRE_V2_NONE] = "Vulnerable", - [SPECTRE_V2_RETPOLINE_GENERIC] = "Mitigation: Full generic retpoline", - [SPECTRE_V2_RETPOLINE_AMD] = "Mitigation: Full AMD retpoline", - [SPECTRE_V2_IBRS_ENHANCED] = "Mitigation: Enhanced IBRS", +enum bhi_mitigations { + BHI_MITIGATION_OFF, + BHI_MITIGATION_AUTO, + BHI_MITIGATION_ON, + BHI_MITIGATION_VMEXIT_ONLY, }; -static const struct { - const char *option; - enum spectre_v2_mitigation_cmd cmd; - bool secure; -} mitigation_options[] __initconst = { - { "off", SPECTRE_V2_CMD_NONE, false }, - { "on", SPECTRE_V2_CMD_FORCE, true }, - { "retpoline", SPECTRE_V2_CMD_RETPOLINE, false }, - { "retpoline,amd", SPECTRE_V2_CMD_RETPOLINE_AMD, false }, - { "retpoline,generic", SPECTRE_V2_CMD_RETPOLINE_GENERIC, false }, - { "auto", SPECTRE_V2_CMD_AUTO, false }, -}; +static enum bhi_mitigations bhi_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_AUTO : BHI_MITIGATION_OFF; -static void __init spec_v2_print_cond(const char *reason, bool secure) +static int __init spectre_bhi_parse_cmdline(char *str) { - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure) - pr_info("%s selected on command line.\n", reason); + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) + bhi_mitigation = BHI_MITIGATION_OFF; + else if (!strcmp(str, "on")) + bhi_mitigation = BHI_MITIGATION_ON; + else if (!strcmp(str, "vmexit")) + bhi_mitigation = BHI_MITIGATION_VMEXIT_ONLY; + else + pr_err("Ignoring unknown spectre_bhi option (%s)", str); + + return 0; } +early_param("spectre_bhi", spectre_bhi_parse_cmdline); -static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) +static void __init bhi_select_mitigation(void) { - enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO; - char arg[20]; - int ret, i; + if (!boot_cpu_has(X86_BUG_BHI)) + bhi_mitigation = BHI_MITIGATION_OFF; - if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") || - cpu_mitigations_off()) - return SPECTRE_V2_CMD_NONE; - - ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg)); - if (ret < 0) - return SPECTRE_V2_CMD_AUTO; + if (bhi_mitigation != BHI_MITIGATION_AUTO) + return; - for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) { - if (!match_option(arg, ret, mitigation_options[i].option)) - continue; - cmd = mitigation_options[i].cmd; - break; + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST)) { + if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL)) + bhi_mitigation = BHI_MITIGATION_ON; + else + bhi_mitigation = BHI_MITIGATION_VMEXIT_ONLY; + } else { + bhi_mitigation = BHI_MITIGATION_OFF; } +} - if (i >= ARRAY_SIZE(mitigation_options)) { - pr_err("unknown option (%s). Switching to AUTO select\n", arg); - return SPECTRE_V2_CMD_AUTO; - } +static void __init bhi_update_mitigation(void) +{ + if (spectre_v2_cmd == SPECTRE_V2_CMD_NONE) + bhi_mitigation = BHI_MITIGATION_OFF; +} + +static void __init bhi_apply_mitigation(void) +{ + if (bhi_mitigation == BHI_MITIGATION_OFF) + return; - if ((cmd == SPECTRE_V2_CMD_RETPOLINE || - cmd == SPECTRE_V2_CMD_RETPOLINE_AMD || - cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) && - !IS_ENABLED(CONFIG_RETPOLINE)) { - pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; + /* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */ + if (boot_cpu_has(X86_FEATURE_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) { + spec_ctrl_disable_kernel_rrsba(); + if (rrsba_disabled) + return; } - if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD && - boot_cpu_data.x86_vendor != X86_VENDOR_HYGON && - boot_cpu_data.x86_vendor != X86_VENDOR_AMD) { - pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n"); - return SPECTRE_V2_CMD_AUTO; + if (!IS_ENABLED(CONFIG_X86_64)) + return; + + /* Mitigate in hardware if supported */ + if (spec_ctrl_bhi_dis()) + return; + + if (bhi_mitigation == BHI_MITIGATION_VMEXIT_ONLY) { + pr_info("Spectre BHI mitigation: SW BHB clearing on VM exit only\n"); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_VMEXIT); + return; } - spec_v2_print_cond(mitigation_options[i].option, - mitigation_options[i].secure); - return cmd; + pr_info("Spectre BHI mitigation: SW BHB clearing on syscall and VM exit\n"); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_VMEXIT); } static void __init spectre_v2_select_mitigation(void) { - enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline(); - enum spectre_v2_mitigation mode = SPECTRE_V2_NONE; + if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE || + spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && + !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) { + pr_err("RETPOLINE selected but not compiled in. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } - /* - * If the CPU is not affected and the command line mode is NONE or AUTO - * then nothing to do. - */ - if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && - (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO)) + if ((spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { + pr_err("EIBRS selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) && + !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { + pr_err("LFENCE selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) { + pr_err("IBRS selected but not compiled in. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { + pr_err("IBRS selected but not Intel CPU. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) { + pr_err("IBRS selected but CPU doesn't have IBRS. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) { + pr_err("IBRS selected but running as XenPV guest. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) { + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; return; + } - switch (cmd) { + switch (spectre_v2_cmd) { case SPECTRE_V2_CMD_NONE: return; - case SPECTRE_V2_CMD_FORCE: case SPECTRE_V2_CMD_AUTO: + if (!should_mitigate_vuln(X86_BUG_SPECTRE_V2)) + break; + fallthrough; + case SPECTRE_V2_CMD_FORCE: if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { - mode = SPECTRE_V2_IBRS_ENHANCED; - /* Force it so VMEXIT will restore correctly */ - x86_spec_ctrl_base |= SPEC_CTRL_IBRS; - wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); - goto specv2_set_mode; + spectre_v2_enabled = SPECTRE_V2_EIBRS; + break; } - if (IS_ENABLED(CONFIG_RETPOLINE)) - goto retpoline_auto; + + spectre_v2_enabled = spectre_v2_select_retpoline(); break; - case SPECTRE_V2_CMD_RETPOLINE_AMD: - if (IS_ENABLED(CONFIG_RETPOLINE)) - goto retpoline_amd; + + case SPECTRE_V2_CMD_RETPOLINE_LFENCE: + pr_err(SPECTRE_V2_LFENCE_MSG); + spectre_v2_enabled = SPECTRE_V2_LFENCE; break; + case SPECTRE_V2_CMD_RETPOLINE_GENERIC: - if (IS_ENABLED(CONFIG_RETPOLINE)) - goto retpoline_generic; + spectre_v2_enabled = SPECTRE_V2_RETPOLINE; break; + case SPECTRE_V2_CMD_RETPOLINE: - if (IS_ENABLED(CONFIG_RETPOLINE)) - goto retpoline_auto; + spectre_v2_enabled = spectre_v2_select_retpoline(); + break; + + case SPECTRE_V2_CMD_IBRS: + spectre_v2_enabled = SPECTRE_V2_IBRS; + break; + + case SPECTRE_V2_CMD_EIBRS: + spectre_v2_enabled = SPECTRE_V2_EIBRS; + break; + + case SPECTRE_V2_CMD_EIBRS_LFENCE: + spectre_v2_enabled = SPECTRE_V2_EIBRS_LFENCE; + break; + + case SPECTRE_V2_CMD_EIBRS_RETPOLINE: + spectre_v2_enabled = SPECTRE_V2_EIBRS_RETPOLINE; break; } - pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!"); - return; +} -retpoline_auto: - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || - boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { - retpoline_amd: - if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { - pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n"); - goto retpoline_generic; +static void __init spectre_v2_update_mitigation(void) +{ + if (spectre_v2_cmd == SPECTRE_V2_CMD_AUTO && + !spectre_v2_in_eibrs_mode(spectre_v2_enabled)) { + if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) && + boot_cpu_has_bug(X86_BUG_RETBLEED) && + retbleed_mitigation != RETBLEED_MITIGATION_NONE && + retbleed_mitigation != RETBLEED_MITIGATION_STUFF && + boot_cpu_has(X86_FEATURE_IBRS) && + boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + spectre_v2_enabled = SPECTRE_V2_IBRS; + } + } + + if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) + pr_info("%s\n", spectre_v2_strings[spectre_v2_enabled]); +} + +static void __init spectre_v2_apply_mitigation(void) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); + + if (spectre_v2_in_ibrs_mode(spectre_v2_enabled)) { + if (boot_cpu_has(X86_FEATURE_AUTOIBRS)) { + msr_set_bit(MSR_EFER, _EFER_AUTOIBRS); + } else { + x86_spec_ctrl_base |= SPEC_CTRL_IBRS; + update_spec_ctrl(x86_spec_ctrl_base); } - mode = SPECTRE_V2_RETPOLINE_AMD; - setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD); - setup_force_cpu_cap(X86_FEATURE_RETPOLINE); - } else { - retpoline_generic: - mode = SPECTRE_V2_RETPOLINE_GENERIC; - setup_force_cpu_cap(X86_FEATURE_RETPOLINE); } -specv2_set_mode: - spectre_v2_enabled = mode; - pr_info("%s\n", spectre_v2_strings[mode]); + switch (spectre_v2_enabled) { + case SPECTRE_V2_NONE: + return; + + case SPECTRE_V2_EIBRS: + break; + + case SPECTRE_V2_IBRS: + setup_force_cpu_cap(X86_FEATURE_KERNEL_IBRS); + if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) + pr_warn(SPECTRE_V2_IBRS_PERF_MSG); + break; + + case SPECTRE_V2_LFENCE: + case SPECTRE_V2_EIBRS_LFENCE: + setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE); + fallthrough; + + case SPECTRE_V2_RETPOLINE: + case SPECTRE_V2_EIBRS_RETPOLINE: + setup_force_cpu_cap(X86_FEATURE_RETPOLINE); + break; + } /* - * If spectre v2 protection has been enabled, unconditionally fill - * RSB during a context switch; this protects against two independent - * issues: - * - * - RSB underflow (and switch to BTB) on Skylake+ - * - SpectreRSB variant of spectre v2 on X86_BUG_SPECTRE_V2 CPUs + * Disable alternate RSB predictions in kernel when indirect CALLs and + * JMPs gets protection against BHI and Intramode-BTI, but RET + * prediction from a non-RSB predictor is still a risk. */ - setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW); - pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n"); + if (spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE || + spectre_v2_enabled == SPECTRE_V2_EIBRS_RETPOLINE || + spectre_v2_enabled == SPECTRE_V2_RETPOLINE) + spec_ctrl_disable_kernel_rrsba(); + + spectre_v2_select_rsb_mitigation(spectre_v2_enabled); /* - * Retpoline means the kernel is safe because it has no indirect - * branches. Enhanced IBRS protects firmware too, so, enable restricted - * speculation around firmware calls only when Enhanced IBRS isn't - * supported. + * Retpoline protects the kernel, but doesn't protect firmware. IBRS + * and Enhanced IBRS protect firmware too, so enable IBRS around + * firmware calls only when IBRS / Enhanced / Automatic IBRS aren't + * otherwise enabled. * - * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because - * the user might select retpoline on the kernel command line and if - * the CPU supports Enhanced IBRS, kernel might un-intentionally not - * enable IBRS around firmware calls. + * Use "spectre_v2_enabled" to check Enhanced IBRS instead of + * boot_cpu_has(), because the user might select retpoline on the kernel + * command line and if the CPU supports Enhanced IBRS, kernel might + * un-intentionally not enable IBRS around firmware calls. */ - if (boot_cpu_has(X86_FEATURE_IBRS) && mode != SPECTRE_V2_IBRS_ENHANCED) { + if (boot_cpu_has_bug(X86_BUG_RETBLEED) && + boot_cpu_has(X86_FEATURE_IBPB) && + (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) { + + if (retbleed_mitigation != RETBLEED_MITIGATION_IBPB) { + setup_force_cpu_cap(X86_FEATURE_USE_IBPB_FW); + pr_info("Enabling Speculation Barrier for firmware calls\n"); + } + + } else if (boot_cpu_has(X86_FEATURE_IBRS) && + !spectre_v2_in_ibrs_mode(spectre_v2_enabled)) { setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW); pr_info("Enabling Restricted Speculation for firmware calls\n"); } - - /* Set up IBPB and STIBP depending on the general spectre V2 command */ - spectre_v2_user_select_mitigation(cmd); } static void update_stibp_msr(void * __unused) { - wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); + u64 val = spec_ctrl_current() | (x86_spec_ctrl_base & SPEC_CTRL_STIBP); + update_spec_ctrl(val); } /* Update x86_spec_ctrl_base in case SMT state changed. */ @@ -1002,70 +2366,19 @@ static void update_mds_branch_idle(void) if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY)) return; - if (sched_smt_active()) - static_branch_enable(&mds_idle_clear); - else - static_branch_disable(&mds_idle_clear); -} - -#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" -#define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n" - -void cpu_bugs_smt_update(void) -{ - mutex_lock(&spec_ctrl_mutex); - - switch (spectre_v2_user_stibp) { - case SPECTRE_V2_USER_NONE: - break; - case SPECTRE_V2_USER_STRICT: - case SPECTRE_V2_USER_STRICT_PREFERRED: - update_stibp_strict(); - break; - case SPECTRE_V2_USER_PRCTL: - case SPECTRE_V2_USER_SECCOMP: - update_indir_branch_cond(); - break; + if (sched_smt_active()) { + static_branch_enable(&cpu_buf_idle_clear); + } else if (mmio_mitigation == MMIO_MITIGATION_OFF || + (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) { + static_branch_disable(&cpu_buf_idle_clear); } - - switch (mds_mitigation) { - case MDS_MITIGATION_FULL: - case MDS_MITIGATION_VMWERV: - if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY)) - pr_warn_once(MDS_MSG_SMT); - update_mds_branch_idle(); - break; - case MDS_MITIGATION_OFF: - break; - } - - switch (taa_mitigation) { - case TAA_MITIGATION_VERW: - case TAA_MITIGATION_UCODE_NEEDED: - if (sched_smt_active()) - pr_warn_once(TAA_MSG_SMT); - break; - case TAA_MITIGATION_TSX_DISABLED: - case TAA_MITIGATION_OFF: - break; - } - - mutex_unlock(&spec_ctrl_mutex); } #undef pr_fmt #define pr_fmt(fmt) "Speculative Store Bypass: " fmt -static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE; - -/* The kernel command line selection */ -enum ssb_mitigation_cmd { - SPEC_STORE_BYPASS_CMD_NONE, - SPEC_STORE_BYPASS_CMD_AUTO, - SPEC_STORE_BYPASS_CMD_ON, - SPEC_STORE_BYPASS_CMD_PRCTL, - SPEC_STORE_BYPASS_CMD_SECCOMP, -}; +static enum ssb_mitigation ssb_mode __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SSB) ? SPEC_STORE_BYPASS_AUTO : SPEC_STORE_BYPASS_NONE; static const char * const ssb_strings[] = { [SPEC_STORE_BYPASS_NONE] = "Vulnerable", @@ -1074,102 +2387,72 @@ static const char * const ssb_strings[] = { [SPEC_STORE_BYPASS_SECCOMP] = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp", }; -static const struct { - const char *option; - enum ssb_mitigation_cmd cmd; -} ssb_mitigation_options[] __initconst = { - { "auto", SPEC_STORE_BYPASS_CMD_AUTO }, /* Platform decides */ - { "on", SPEC_STORE_BYPASS_CMD_ON }, /* Disable Speculative Store Bypass */ - { "off", SPEC_STORE_BYPASS_CMD_NONE }, /* Don't touch Speculative Store Bypass */ - { "prctl", SPEC_STORE_BYPASS_CMD_PRCTL }, /* Disable Speculative Store Bypass via prctl */ - { "seccomp", SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */ -}; +static bool nossb __ro_after_init; -static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) +static int __init nossb_parse_cmdline(char *str) { - enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO; - char arg[20]; - int ret, i; - - if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") || - cpu_mitigations_off()) { - return SPEC_STORE_BYPASS_CMD_NONE; - } else { - ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable", - arg, sizeof(arg)); - if (ret < 0) - return SPEC_STORE_BYPASS_CMD_AUTO; + nossb = true; + ssb_mode = SPEC_STORE_BYPASS_NONE; + return 0; +} +early_param("nospec_store_bypass_disable", nossb_parse_cmdline); - for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) { - if (!match_option(arg, ret, ssb_mitigation_options[i].option)) - continue; +static int __init ssb_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; - cmd = ssb_mitigation_options[i].cmd; - break; - } + if (nossb) + return 0; - if (i >= ARRAY_SIZE(ssb_mitigation_options)) { - pr_err("unknown option (%s). Switching to AUTO select\n", arg); - return SPEC_STORE_BYPASS_CMD_AUTO; - } - } + if (!strcmp(str, "auto")) + ssb_mode = SPEC_STORE_BYPASS_AUTO; + else if (!strcmp(str, "on")) + ssb_mode = SPEC_STORE_BYPASS_DISABLE; + else if (!strcmp(str, "off")) + ssb_mode = SPEC_STORE_BYPASS_NONE; + else if (!strcmp(str, "prctl")) + ssb_mode = SPEC_STORE_BYPASS_PRCTL; + else if (!strcmp(str, "seccomp")) + ssb_mode = IS_ENABLED(CONFIG_SECCOMP) ? + SPEC_STORE_BYPASS_SECCOMP : SPEC_STORE_BYPASS_PRCTL; + else + pr_err("Ignoring unknown spec_store_bypass_disable option (%s).\n", + str); - return cmd; + return 0; } +early_param("spec_store_bypass_disable", ssb_parse_cmdline); -static enum ssb_mitigation __init __ssb_select_mitigation(void) +static void __init ssb_select_mitigation(void) { - enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE; - enum ssb_mitigation_cmd cmd; - - if (!boot_cpu_has(X86_FEATURE_SSBD)) - return mode; - - cmd = ssb_parse_cmdline(); - if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) && - (cmd == SPEC_STORE_BYPASS_CMD_NONE || - cmd == SPEC_STORE_BYPASS_CMD_AUTO)) - return mode; + if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) { + ssb_mode = SPEC_STORE_BYPASS_NONE; + return; + } - switch (cmd) { - case SPEC_STORE_BYPASS_CMD_AUTO: - case SPEC_STORE_BYPASS_CMD_SECCOMP: - /* - * Choose prctl+seccomp as the default mode if seccomp is - * enabled. - */ - if (IS_ENABLED(CONFIG_SECCOMP)) - mode = SPEC_STORE_BYPASS_SECCOMP; + if (ssb_mode == SPEC_STORE_BYPASS_AUTO) { + if (should_mitigate_vuln(X86_BUG_SPEC_STORE_BYPASS)) + ssb_mode = SPEC_STORE_BYPASS_PRCTL; else - mode = SPEC_STORE_BYPASS_PRCTL; - break; - case SPEC_STORE_BYPASS_CMD_ON: - mode = SPEC_STORE_BYPASS_DISABLE; - break; - case SPEC_STORE_BYPASS_CMD_PRCTL: - mode = SPEC_STORE_BYPASS_PRCTL; - break; - case SPEC_STORE_BYPASS_CMD_NONE: - break; + ssb_mode = SPEC_STORE_BYPASS_NONE; } - /* - * If SSBD is controlled by the SPEC_CTRL MSR, then set the proper - * bit in the mask to allow guests to use the mitigation even in the - * case where the host does not enable it. - */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || - static_cpu_has(X86_FEATURE_AMD_SSBD)) { - x86_spec_ctrl_mask |= SPEC_CTRL_SSBD; - } + if (!boot_cpu_has(X86_FEATURE_SSBD)) + ssb_mode = SPEC_STORE_BYPASS_NONE; + + pr_info("%s\n", ssb_strings[ssb_mode]); +} +static void __init ssb_apply_mitigation(void) +{ /* * We have three CPU feature flags that are in play here: * - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible. * - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass * - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation */ - if (mode == SPEC_STORE_BYPASS_DISABLE) { + if (ssb_mode == SPEC_STORE_BYPASS_DISABLE) { setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE); /* * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may @@ -1180,19 +2463,9 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void) x86_amd_ssb_disable(); } else { x86_spec_ctrl_base |= SPEC_CTRL_SSBD; - wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); + update_spec_ctrl(x86_spec_ctrl_base); } } - - return mode; -} - -static void ssb_select_mitigation(void) -{ - ssb_mode = __ssb_select_mitigation(); - - if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) - pr_info("%s\n", ssb_strings[ssb_mode]); } #undef pr_fmt @@ -1215,6 +2488,24 @@ static void task_update_spec_tif(struct task_struct *tsk) speculation_ctrl_update_current(); } +static int l1d_flush_prctl_set(struct task_struct *task, unsigned long ctrl) +{ + + if (!static_branch_unlikely(&switch_mm_cond_l1d_flush)) + return -EPERM; + + switch (ctrl) { + case PR_SPEC_ENABLE: + set_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH); + return 0; + case PR_SPEC_DISABLE: + clear_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH); + return 0; + default: + return -ERANGE; + } +} + static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) { if (ssb_mode != SPEC_STORE_BYPASS_PRCTL && @@ -1309,6 +2600,8 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl) if (ctrl == PR_SPEC_FORCE_DISABLE) task_set_spec_ib_force_disable(task); task_update_spec_tif(task); + if (task == current) + indirect_branch_prediction_barrier(); break; default: return -ERANGE; @@ -1324,6 +2617,8 @@ int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which, return ssb_prctl_set(task, ctrl); case PR_SPEC_INDIRECT_BRANCH: return ib_prctl_set(task, ctrl); + case PR_SPEC_L1D_FLUSH: + return l1d_flush_prctl_set(task, ctrl); default: return -ENODEV; } @@ -1340,13 +2635,29 @@ void arch_seccomp_spec_mitigate(struct task_struct *task) } #endif +static int l1d_flush_prctl_get(struct task_struct *task) +{ + if (!static_branch_unlikely(&switch_mm_cond_l1d_flush)) + return PR_SPEC_FORCE_DISABLE; + + if (test_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH)) + return PR_SPEC_PRCTL | PR_SPEC_ENABLE; + else + return PR_SPEC_PRCTL | PR_SPEC_DISABLE; +} + static int ssb_prctl_get(struct task_struct *task) { switch (ssb_mode) { + case SPEC_STORE_BYPASS_NONE: + if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) + return PR_SPEC_ENABLE; + return PR_SPEC_NOT_AFFECTED; case SPEC_STORE_BYPASS_DISABLE: return PR_SPEC_DISABLE; case SPEC_STORE_BYPASS_SECCOMP: case SPEC_STORE_BYPASS_PRCTL: + case SPEC_STORE_BYPASS_AUTO: if (task_spec_ssb_force_disable(task)) return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; if (task_spec_ssb_noexec(task)) @@ -1354,11 +2665,8 @@ static int ssb_prctl_get(struct task_struct *task) if (task_spec_ssb_disable(task)) return PR_SPEC_PRCTL | PR_SPEC_DISABLE; return PR_SPEC_PRCTL | PR_SPEC_ENABLE; - default: - if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) - return PR_SPEC_ENABLE; - return PR_SPEC_NOT_AFFECTED; } + BUG(); } static int ib_prctl_get(struct task_struct *task) @@ -1390,6 +2698,8 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) return ssb_prctl_get(task); case PR_SPEC_INDIRECT_BRANCH: return ib_prctl_get(task); + case PR_SPEC_L1D_FLUSH: + return l1d_flush_prctl_get(task); default: return -ENODEV; } @@ -1398,25 +2708,24 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) void x86_spec_ctrl_setup_ap(void) { if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) - wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); + update_spec_ctrl(x86_spec_ctrl_base); if (ssb_mode == SPEC_STORE_BYPASS_DISABLE) x86_amd_ssb_disable(); } bool itlb_multihit_kvm_mitigation; -EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation); +EXPORT_SYMBOL_FOR_KVM(itlb_multihit_kvm_mitigation); #undef pr_fmt #define pr_fmt(fmt) "L1TF: " fmt /* Default mitigation for L1TF-affected CPUs */ -enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; -#if IS_ENABLED(CONFIG_KVM_INTEL) -EXPORT_SYMBOL_GPL(l1tf_mitigation); -#endif +enum l1tf_mitigations l1tf_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_AUTO : L1TF_MITIGATION_OFF; +EXPORT_SYMBOL_FOR_KVM(l1tf_mitigation); enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; -EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); +EXPORT_SYMBOL_FOR_KVM(l1tf_vmx_mitigation); /* * These CPUs all support 44bits physical address space internally in the @@ -1437,20 +2746,20 @@ static void override_cache_bits(struct cpuinfo_x86 *c) if (c->x86 != 6) return; - switch (c->x86_model) { - case INTEL_FAM6_NEHALEM: - case INTEL_FAM6_WESTMERE: - case INTEL_FAM6_SANDYBRIDGE: - case INTEL_FAM6_IVYBRIDGE: - case INTEL_FAM6_HASWELL: - case INTEL_FAM6_HASWELL_L: - case INTEL_FAM6_HASWELL_G: - case INTEL_FAM6_BROADWELL: - case INTEL_FAM6_BROADWELL_G: - case INTEL_FAM6_SKYLAKE_L: - case INTEL_FAM6_SKYLAKE: - case INTEL_FAM6_KABYLAKE_L: - case INTEL_FAM6_KABYLAKE: + switch (c->x86_vfm) { + case INTEL_NEHALEM: + case INTEL_WESTMERE: + case INTEL_SANDYBRIDGE: + case INTEL_IVYBRIDGE: + case INTEL_HASWELL: + case INTEL_HASWELL_L: + case INTEL_HASWELL_G: + case INTEL_BROADWELL: + case INTEL_BROADWELL_G: + case INTEL_SKYLAKE_L: + case INTEL_SKYLAKE: + case INTEL_KABYLAKE_L: + case INTEL_KABYLAKE: if (c->x86_cache_bits < 44) c->x86_cache_bits = 44; break; @@ -1459,15 +2768,31 @@ static void override_cache_bits(struct cpuinfo_x86 *c) static void __init l1tf_select_mitigation(void) { - u64 half_pa; + if (!boot_cpu_has_bug(X86_BUG_L1TF)) { + l1tf_mitigation = L1TF_MITIGATION_OFF; + return; + } - if (!boot_cpu_has_bug(X86_BUG_L1TF)) + if (l1tf_mitigation != L1TF_MITIGATION_AUTO) return; - if (cpu_mitigations_off()) + if (!should_mitigate_vuln(X86_BUG_L1TF)) { l1tf_mitigation = L1TF_MITIGATION_OFF; - else if (cpu_mitigations_auto_nosmt()) + return; + } + + if (smt_mitigations == SMT_MITIGATIONS_ON) l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; + else + l1tf_mitigation = L1TF_MITIGATION_FLUSH; +} + +static void __init l1tf_apply_mitigation(void) +{ + u64 half_pa; + + if (!boot_cpu_has_bug(X86_BUG_L1TF)) + return; override_cache_bits(&boot_cpu_data); @@ -1475,6 +2800,7 @@ static void __init l1tf_select_mitigation(void) case L1TF_MITIGATION_OFF: case L1TF_MITIGATION_FLUSH_NOWARN: case L1TF_MITIGATION_FLUSH: + case L1TF_MITIGATION_AUTO: break; case L1TF_MITIGATION_FLUSH_NOSMT: case L1TF_MITIGATION_FULL: @@ -1530,8 +2856,468 @@ static int __init l1tf_cmdline(char *str) early_param("l1tf", l1tf_cmdline); #undef pr_fmt +#define pr_fmt(fmt) "Speculative Return Stack Overflow: " fmt + +static const char * const srso_strings[] = { + [SRSO_MITIGATION_NONE] = "Vulnerable", + [SRSO_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", + [SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED] = "Vulnerable: Safe RET, no microcode", + [SRSO_MITIGATION_MICROCODE] = "Vulnerable: Microcode, no safe RET", + [SRSO_MITIGATION_NOSMT] = "Mitigation: SMT disabled", + [SRSO_MITIGATION_SAFE_RET] = "Mitigation: Safe RET", + [SRSO_MITIGATION_IBPB] = "Mitigation: IBPB", + [SRSO_MITIGATION_IBPB_ON_VMEXIT] = "Mitigation: IBPB on VMEXIT only", + [SRSO_MITIGATION_BP_SPEC_REDUCE] = "Mitigation: Reduced Speculation" +}; + +static int __init srso_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) + srso_mitigation = SRSO_MITIGATION_NONE; + else if (!strcmp(str, "microcode")) + srso_mitigation = SRSO_MITIGATION_MICROCODE; + else if (!strcmp(str, "safe-ret")) + srso_mitigation = SRSO_MITIGATION_SAFE_RET; + else if (!strcmp(str, "ibpb")) + srso_mitigation = SRSO_MITIGATION_IBPB; + else if (!strcmp(str, "ibpb-vmexit")) + srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT; + else + pr_err("Ignoring unknown SRSO option (%s).", str); + + return 0; +} +early_param("spec_rstack_overflow", srso_parse_cmdline); + +#define SRSO_NOTICE "WARNING: See https://kernel.org/doc/html/latest/admin-guide/hw-vuln/srso.html for mitigation options." + +static void __init srso_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_SRSO)) { + srso_mitigation = SRSO_MITIGATION_NONE; + return; + } + + if (srso_mitigation == SRSO_MITIGATION_AUTO) { + /* + * Use safe-RET if user->kernel or guest->host protection is + * required. Otherwise the 'microcode' mitigation is sufficient + * to protect the user->user and guest->guest vectors. + */ + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST) || + (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL) && + !boot_cpu_has(X86_FEATURE_SRSO_USER_KERNEL_NO))) { + srso_mitigation = SRSO_MITIGATION_SAFE_RET; + } else if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER) || + cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST)) { + srso_mitigation = SRSO_MITIGATION_MICROCODE; + } else { + srso_mitigation = SRSO_MITIGATION_NONE; + return; + } + } + + /* Zen1/2 with SMT off aren't vulnerable to SRSO. */ + if (boot_cpu_data.x86 < 0x19 && !cpu_smt_possible()) { + srso_mitigation = SRSO_MITIGATION_NOSMT; + return; + } + + if (!boot_cpu_has(X86_FEATURE_IBPB_BRTYPE)) { + pr_warn("IBPB-extending microcode not applied!\n"); + pr_warn(SRSO_NOTICE); + + /* + * Safe-RET provides partial mitigation without microcode, but + * other mitigations require microcode to provide any + * mitigations. + */ + if (srso_mitigation == SRSO_MITIGATION_SAFE_RET) + srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED; + else + srso_mitigation = SRSO_MITIGATION_UCODE_NEEDED; + } + + switch (srso_mitigation) { + case SRSO_MITIGATION_SAFE_RET: + case SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED: + if (boot_cpu_has(X86_FEATURE_SRSO_USER_KERNEL_NO)) { + srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT; + goto ibpb_on_vmexit; + } + + if (!IS_ENABLED(CONFIG_MITIGATION_SRSO)) { + pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n"); + srso_mitigation = SRSO_MITIGATION_NONE; + } + break; +ibpb_on_vmexit: + case SRSO_MITIGATION_IBPB_ON_VMEXIT: + if (boot_cpu_has(X86_FEATURE_SRSO_BP_SPEC_REDUCE)) { + pr_notice("Reducing speculation to address VM/HV SRSO attack vector.\n"); + srso_mitigation = SRSO_MITIGATION_BP_SPEC_REDUCE; + break; + } + fallthrough; + case SRSO_MITIGATION_IBPB: + if (!IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { + pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n"); + srso_mitigation = SRSO_MITIGATION_NONE; + } + break; + default: + break; + } +} + +static void __init srso_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_SRSO)) + return; + + /* If retbleed is using IBPB, that works for SRSO as well */ + if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB && + boot_cpu_has(X86_FEATURE_IBPB_BRTYPE)) + srso_mitigation = SRSO_MITIGATION_IBPB; + + pr_info("%s\n", srso_strings[srso_mitigation]); +} + +static void __init srso_apply_mitigation(void) +{ + /* + * Clear the feature flag if this mitigation is not selected as that + * feature flag controls the BpSpecReduce MSR bit toggling in KVM. + */ + if (srso_mitigation != SRSO_MITIGATION_BP_SPEC_REDUCE) + setup_clear_cpu_cap(X86_FEATURE_SRSO_BP_SPEC_REDUCE); + + if (srso_mitigation == SRSO_MITIGATION_NONE) { + if (boot_cpu_has(X86_FEATURE_SBPB)) + x86_pred_cmd = PRED_CMD_SBPB; + return; + } + + switch (srso_mitigation) { + case SRSO_MITIGATION_SAFE_RET: + case SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED: + /* + * Enable the return thunk for generated code + * like ftrace, static_call, etc. + */ + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_UNRET); + + if (boot_cpu_data.x86 == 0x19) { + setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS); + set_return_thunk(srso_alias_return_thunk); + } else { + setup_force_cpu_cap(X86_FEATURE_SRSO); + set_return_thunk(srso_return_thunk); + } + break; + case SRSO_MITIGATION_IBPB: + setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB); + /* + * IBPB on entry already obviates the need for + * software-based untraining so clear those in case some + * other mitigation like Retbleed has selected them. + */ + setup_clear_cpu_cap(X86_FEATURE_UNRET); + setup_clear_cpu_cap(X86_FEATURE_RETHUNK); + fallthrough; + case SRSO_MITIGATION_IBPB_ON_VMEXIT: + setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT); + /* + * There is no need for RSB filling: entry_ibpb() ensures + * all predictions, including the RSB, are invalidated, + * regardless of IBPB implementation. + */ + setup_clear_cpu_cap(X86_FEATURE_RSB_VMEXIT); + break; + default: + break; + } +} + +#undef pr_fmt +#define pr_fmt(fmt) "VMSCAPE: " fmt + +enum vmscape_mitigations { + VMSCAPE_MITIGATION_NONE, + VMSCAPE_MITIGATION_AUTO, + VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER, + VMSCAPE_MITIGATION_IBPB_ON_VMEXIT, +}; + +static const char * const vmscape_strings[] = { + [VMSCAPE_MITIGATION_NONE] = "Vulnerable", + /* [VMSCAPE_MITIGATION_AUTO] */ + [VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER] = "Mitigation: IBPB before exit to userspace", + [VMSCAPE_MITIGATION_IBPB_ON_VMEXIT] = "Mitigation: IBPB on VMEXIT", +}; + +static enum vmscape_mitigations vmscape_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_VMSCAPE) ? VMSCAPE_MITIGATION_AUTO : VMSCAPE_MITIGATION_NONE; + +static int __init vmscape_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) { + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + } else if (!strcmp(str, "ibpb")) { + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; + } else if (!strcmp(str, "force")) { + setup_force_cpu_bug(X86_BUG_VMSCAPE); + vmscape_mitigation = VMSCAPE_MITIGATION_AUTO; + } else { + pr_err("Ignoring unknown vmscape=%s option.\n", str); + } + + return 0; +} +early_param("vmscape", vmscape_parse_cmdline); + +static void __init vmscape_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE) || + !boot_cpu_has(X86_FEATURE_IBPB)) { + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + return; + } + + if (vmscape_mitigation == VMSCAPE_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_VMSCAPE)) + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; + else + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + } +} + +static void __init vmscape_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE)) + return; + + if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB || + srso_mitigation == SRSO_MITIGATION_IBPB_ON_VMEXIT) + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_ON_VMEXIT; + + pr_info("%s\n", vmscape_strings[vmscape_mitigation]); +} + +static void __init vmscape_apply_mitigation(void) +{ + if (vmscape_mitigation == VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER) + setup_force_cpu_cap(X86_FEATURE_IBPB_EXIT_TO_USER); +} + +#undef pr_fmt #define pr_fmt(fmt) fmt +#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" +#define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n" +#define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n" +#define VMSCAPE_MSG_SMT "VMSCAPE: SMT on, STIBP is required for full protection. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/vmscape.html for more details.\n" + +void cpu_bugs_smt_update(void) +{ + mutex_lock(&spec_ctrl_mutex); + + if (sched_smt_active() && unprivileged_ebpf_enabled() && + spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE) + pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG); + + switch (spectre_v2_user_stibp) { + case SPECTRE_V2_USER_NONE: + break; + case SPECTRE_V2_USER_STRICT: + case SPECTRE_V2_USER_STRICT_PREFERRED: + update_stibp_strict(); + break; + case SPECTRE_V2_USER_PRCTL: + case SPECTRE_V2_USER_SECCOMP: + update_indir_branch_cond(); + break; + } + + switch (mds_mitigation) { + case MDS_MITIGATION_FULL: + case MDS_MITIGATION_AUTO: + case MDS_MITIGATION_VMWERV: + if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY)) + pr_warn_once(MDS_MSG_SMT); + update_mds_branch_idle(); + break; + case MDS_MITIGATION_OFF: + break; + } + + switch (taa_mitigation) { + case TAA_MITIGATION_VERW: + case TAA_MITIGATION_AUTO: + case TAA_MITIGATION_UCODE_NEEDED: + if (sched_smt_active()) + pr_warn_once(TAA_MSG_SMT); + break; + case TAA_MITIGATION_TSX_DISABLED: + case TAA_MITIGATION_OFF: + break; + } + + switch (mmio_mitigation) { + case MMIO_MITIGATION_VERW: + case MMIO_MITIGATION_AUTO: + case MMIO_MITIGATION_UCODE_NEEDED: + if (sched_smt_active()) + pr_warn_once(MMIO_MSG_SMT); + break; + case MMIO_MITIGATION_OFF: + break; + } + + switch (tsa_mitigation) { + case TSA_MITIGATION_USER_KERNEL: + case TSA_MITIGATION_VM: + case TSA_MITIGATION_AUTO: + case TSA_MITIGATION_FULL: + /* + * TSA-SQ can potentially lead to info leakage between + * SMT threads. + */ + if (sched_smt_active()) + static_branch_enable(&cpu_buf_idle_clear); + else + static_branch_disable(&cpu_buf_idle_clear); + break; + case TSA_MITIGATION_NONE: + case TSA_MITIGATION_UCODE_NEEDED: + break; + } + + switch (vmscape_mitigation) { + case VMSCAPE_MITIGATION_NONE: + case VMSCAPE_MITIGATION_AUTO: + break; + case VMSCAPE_MITIGATION_IBPB_ON_VMEXIT: + case VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER: + /* + * Hypervisors can be attacked across-threads, warn for SMT when + * STIBP is not already enabled system-wide. + * + * Intel eIBRS (!AUTOIBRS) implies STIBP on. + */ + if (!sched_smt_active() || + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT || + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED || + (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && + !boot_cpu_has(X86_FEATURE_AUTOIBRS))) + break; + pr_warn_once(VMSCAPE_MSG_SMT); + break; + } + + mutex_unlock(&spec_ctrl_mutex); +} + +void __init cpu_select_mitigations(void) +{ + /* + * Read the SPEC_CTRL MSR to account for reserved bits which may + * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD + * init code as it is not enumerated and depends on the family. + */ + if (cpu_feature_enabled(X86_FEATURE_MSR_SPEC_CTRL)) { + rdmsrq(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); + + /* + * Previously running kernel (kexec), may have some controls + * turned ON. Clear them and let the mitigations setup below + * rediscover them based on configuration. + */ + x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK; + } + + x86_arch_cap_msr = x86_read_arch_cap_msr(); + + cpu_print_attack_vectors(); + + /* Select the proper CPU mitigations before patching alternatives: */ + spectre_v1_select_mitigation(); + spectre_v2_select_mitigation(); + retbleed_select_mitigation(); + spectre_v2_user_select_mitigation(); + ssb_select_mitigation(); + l1tf_select_mitigation(); + mds_select_mitigation(); + taa_select_mitigation(); + mmio_select_mitigation(); + rfds_select_mitigation(); + srbds_select_mitigation(); + l1d_flush_select_mitigation(); + srso_select_mitigation(); + gds_select_mitigation(); + its_select_mitigation(); + bhi_select_mitigation(); + tsa_select_mitigation(); + vmscape_select_mitigation(); + + /* + * After mitigations are selected, some may need to update their + * choices. + */ + spectre_v2_update_mitigation(); + /* + * retbleed_update_mitigation() relies on the state set by + * spectre_v2_update_mitigation(); specifically it wants to know about + * spectre_v2=ibrs. + */ + retbleed_update_mitigation(); + /* + * its_update_mitigation() depends on spectre_v2_update_mitigation() + * and retbleed_update_mitigation(). + */ + its_update_mitigation(); + + /* + * spectre_v2_user_update_mitigation() depends on + * retbleed_update_mitigation(), specifically the STIBP + * selection is forced for UNRET or IBPB. + */ + spectre_v2_user_update_mitigation(); + mds_update_mitigation(); + taa_update_mitigation(); + mmio_update_mitigation(); + rfds_update_mitigation(); + bhi_update_mitigation(); + /* srso_update_mitigation() depends on retbleed_update_mitigation(). */ + srso_update_mitigation(); + vmscape_update_mitigation(); + + spectre_v1_apply_mitigation(); + spectre_v2_apply_mitigation(); + retbleed_apply_mitigation(); + spectre_v2_user_apply_mitigation(); + ssb_apply_mitigation(); + l1tf_apply_mitigation(); + mds_apply_mitigation(); + taa_apply_mitigation(); + mmio_apply_mitigation(); + rfds_apply_mitigation(); + srbds_apply_mitigation(); + srso_apply_mitigation(); + gds_apply_mitigation(); + its_apply_mitigation(); + bhi_apply_mitigation(); + tsa_apply_mitigation(); + vmscape_apply_mitigation(); +} + #ifdef CONFIG_SYSFS #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion" @@ -1549,92 +3335,125 @@ static const char * const l1tf_vmx_states[] = { static ssize_t l1tf_show_state(char *buf) { if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO) - return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG); + return sysfs_emit(buf, "%s\n", L1TF_DEFAULT_MSG); if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED || (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER && sched_smt_active())) { - return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG, - l1tf_vmx_states[l1tf_vmx_mitigation]); + return sysfs_emit(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG, + l1tf_vmx_states[l1tf_vmx_mitigation]); } - return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG, - l1tf_vmx_states[l1tf_vmx_mitigation], - sched_smt_active() ? "vulnerable" : "disabled"); + return sysfs_emit(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG, + l1tf_vmx_states[l1tf_vmx_mitigation], + sched_smt_active() ? "vulnerable" : "disabled"); } static ssize_t itlb_multihit_show_state(char *buf) { if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) || !boot_cpu_has(X86_FEATURE_VMX)) - return sprintf(buf, "KVM: Mitigation: VMX unsupported\n"); + return sysfs_emit(buf, "KVM: Mitigation: VMX unsupported\n"); else if (!(cr4_read_shadow() & X86_CR4_VMXE)) - return sprintf(buf, "KVM: Mitigation: VMX disabled\n"); + return sysfs_emit(buf, "KVM: Mitigation: VMX disabled\n"); else if (itlb_multihit_kvm_mitigation) - return sprintf(buf, "KVM: Mitigation: Split huge pages\n"); + return sysfs_emit(buf, "KVM: Mitigation: Split huge pages\n"); else - return sprintf(buf, "KVM: Vulnerable\n"); + return sysfs_emit(buf, "KVM: Vulnerable\n"); } #else static ssize_t l1tf_show_state(char *buf) { - return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG); + return sysfs_emit(buf, "%s\n", L1TF_DEFAULT_MSG); } static ssize_t itlb_multihit_show_state(char *buf) { - return sprintf(buf, "Processor vulnerable\n"); + return sysfs_emit(buf, "Processor vulnerable\n"); } #endif static ssize_t mds_show_state(char *buf) { if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { - return sprintf(buf, "%s; SMT Host state unknown\n", - mds_strings[mds_mitigation]); + return sysfs_emit(buf, "%s; SMT Host state unknown\n", + mds_strings[mds_mitigation]); } if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) { - return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], - (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" : - sched_smt_active() ? "mitigated" : "disabled")); + return sysfs_emit(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], + (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" : + sched_smt_active() ? "mitigated" : "disabled")); } - return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], - sched_smt_active() ? "vulnerable" : "disabled"); + return sysfs_emit(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], + sched_smt_active() ? "vulnerable" : "disabled"); } static ssize_t tsx_async_abort_show_state(char *buf) { if ((taa_mitigation == TAA_MITIGATION_TSX_DISABLED) || (taa_mitigation == TAA_MITIGATION_OFF)) - return sprintf(buf, "%s\n", taa_strings[taa_mitigation]); + return sysfs_emit(buf, "%s\n", taa_strings[taa_mitigation]); if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { - return sprintf(buf, "%s; SMT Host state unknown\n", - taa_strings[taa_mitigation]); + return sysfs_emit(buf, "%s; SMT Host state unknown\n", + taa_strings[taa_mitigation]); } - return sprintf(buf, "%s; SMT %s\n", taa_strings[taa_mitigation], - sched_smt_active() ? "vulnerable" : "disabled"); + return sysfs_emit(buf, "%s; SMT %s\n", taa_strings[taa_mitigation], + sched_smt_active() ? "vulnerable" : "disabled"); +} + +static ssize_t mmio_stale_data_show_state(char *buf) +{ + if (mmio_mitigation == MMIO_MITIGATION_OFF) + return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]); + + if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { + return sysfs_emit(buf, "%s; SMT Host state unknown\n", + mmio_strings[mmio_mitigation]); + } + + return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation], + sched_smt_active() ? "vulnerable" : "disabled"); +} + +static ssize_t rfds_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", rfds_strings[rfds_mitigation]); +} + +static ssize_t old_microcode_show_state(char *buf) +{ + if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) + return sysfs_emit(buf, "Unknown: running under hypervisor"); + + return sysfs_emit(buf, "Vulnerable\n"); +} + +static ssize_t its_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", its_strings[its_mitigation]); } static char *stibp_state(void) { - if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && + !boot_cpu_has(X86_FEATURE_AUTOIBRS)) return ""; switch (spectre_v2_user_stibp) { case SPECTRE_V2_USER_NONE: - return ", STIBP: disabled"; + return "; STIBP: disabled"; case SPECTRE_V2_USER_STRICT: - return ", STIBP: forced"; + return "; STIBP: forced"; case SPECTRE_V2_USER_STRICT_PREFERRED: - return ", STIBP: always-on"; + return "; STIBP: always-on"; case SPECTRE_V2_USER_PRCTL: case SPECTRE_V2_USER_SECCOMP: if (static_key_enabled(&switch_to_cond_stibp)) - return ", STIBP: conditional"; + return "; STIBP: conditional"; } return ""; } @@ -1643,48 +3462,133 @@ static char *ibpb_state(void) { if (boot_cpu_has(X86_FEATURE_IBPB)) { if (static_key_enabled(&switch_mm_always_ibpb)) - return ", IBPB: always-on"; + return "; IBPB: always-on"; if (static_key_enabled(&switch_mm_cond_ibpb)) - return ", IBPB: conditional"; - return ", IBPB: disabled"; + return "; IBPB: conditional"; + return "; IBPB: disabled"; } return ""; } +static char *pbrsb_eibrs_state(void) +{ + if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) { + if (boot_cpu_has(X86_FEATURE_RSB_VMEXIT_LITE) || + boot_cpu_has(X86_FEATURE_RSB_VMEXIT)) + return "; PBRSB-eIBRS: SW sequence"; + else + return "; PBRSB-eIBRS: Vulnerable"; + } else { + return "; PBRSB-eIBRS: Not affected"; + } +} + +static const char *spectre_bhi_state(void) +{ + if (!boot_cpu_has_bug(X86_BUG_BHI)) + return "; BHI: Not affected"; + else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW)) + return "; BHI: BHI_DIS_S"; + else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP)) + return "; BHI: SW loop, KVM: SW loop"; + else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE) && + rrsba_disabled) + return "; BHI: Retpoline"; + else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_VMEXIT)) + return "; BHI: Vulnerable, KVM: SW loop"; + + return "; BHI: Vulnerable"; +} + +static ssize_t spectre_v2_show_state(char *buf) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + return sysfs_emit(buf, "Vulnerable: eIBRS with unprivileged eBPF\n"); + + if (sched_smt_active() && unprivileged_ebpf_enabled() && + spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE) + return sysfs_emit(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n"); + + return sysfs_emit(buf, "%s%s%s%s%s%s%s%s\n", + spectre_v2_strings[spectre_v2_enabled], + ibpb_state(), + boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? "; IBRS_FW" : "", + stibp_state(), + boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? "; RSB filling" : "", + pbrsb_eibrs_state(), + spectre_bhi_state(), + /* this should always be at the end */ + spectre_v2_module_string()); +} + static ssize_t srbds_show_state(char *buf) { - return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]); + return sysfs_emit(buf, "%s\n", srbds_strings[srbds_mitigation]); +} + +static ssize_t retbleed_show_state(char *buf) +{ + if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || + retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && + boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) + return sysfs_emit(buf, "Vulnerable: untrained return thunk / IBPB on non-AMD based uarch\n"); + + return sysfs_emit(buf, "%s; SMT %s\n", retbleed_strings[retbleed_mitigation], + !sched_smt_active() ? "disabled" : + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT || + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ? + "enabled with STIBP protection" : "vulnerable"); + } + + return sysfs_emit(buf, "%s\n", retbleed_strings[retbleed_mitigation]); +} + +static ssize_t srso_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", srso_strings[srso_mitigation]); +} + +static ssize_t gds_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", gds_strings[gds_mitigation]); +} + +static ssize_t tsa_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", tsa_strings[tsa_mitigation]); +} + +static ssize_t vmscape_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", vmscape_strings[vmscape_mitigation]); } static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr, char *buf, unsigned int bug) { if (!boot_cpu_has_bug(bug)) - return sprintf(buf, "Not affected\n"); + return sysfs_emit(buf, "Not affected\n"); switch (bug) { case X86_BUG_CPU_MELTDOWN: if (boot_cpu_has(X86_FEATURE_PTI)) - return sprintf(buf, "Mitigation: PTI\n"); + return sysfs_emit(buf, "Mitigation: PTI\n"); if (hypervisor_is_type(X86_HYPER_XEN_PV)) - return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n"); + return sysfs_emit(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n"); break; case X86_BUG_SPECTRE_V1: - return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]); + return sysfs_emit(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]); case X86_BUG_SPECTRE_V2: - return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], - ibpb_state(), - boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", - stibp_state(), - boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", - spectre_v2_module_string()); + return spectre_v2_show_state(buf); case X86_BUG_SPEC_STORE_BYPASS: - return sprintf(buf, "%s\n", ssb_strings[ssb_mode]); + return sysfs_emit(buf, "%s\n", ssb_strings[ssb_mode]); case X86_BUG_L1TF: if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV)) @@ -1703,11 +3607,38 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr case X86_BUG_SRBDS: return srbds_show_state(buf); + case X86_BUG_MMIO_STALE_DATA: + return mmio_stale_data_show_state(buf); + + case X86_BUG_RETBLEED: + return retbleed_show_state(buf); + + case X86_BUG_SRSO: + return srso_show_state(buf); + + case X86_BUG_GDS: + return gds_show_state(buf); + + case X86_BUG_RFDS: + return rfds_show_state(buf); + + case X86_BUG_OLD_MICROCODE: + return old_microcode_show_state(buf); + + case X86_BUG_ITS: + return its_show_state(buf); + + case X86_BUG_TSA: + return tsa_show_state(buf); + + case X86_BUG_VMSCAPE: + return vmscape_show_state(buf); + default: break; } - return sprintf(buf, "Vulnerable\n"); + return sysfs_emit(buf, "Vulnerable\n"); } ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) @@ -1754,4 +3685,54 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char * { return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS); } + +ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA); +} + +ssize_t cpu_show_retbleed(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_RETBLEED); +} + +ssize_t cpu_show_spec_rstack_overflow(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_SRSO); +} + +ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_GDS); +} + +ssize_t cpu_show_reg_file_data_sampling(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_RFDS); +} + +ssize_t cpu_show_old_microcode(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_OLD_MICROCODE); +} + +ssize_t cpu_show_indirect_target_selection(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_ITS); +} + +ssize_t cpu_show_tsa(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_TSA); +} + +ssize_t cpu_show_vmscape(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_VMSCAPE); +} #endif + +void __warn_thunk(void) +{ + WARN_ONCE(1, "Unpatched return thunk in use. This should not happen!\n"); +} |