summaryrefslogtreecommitdiff
path: root/arch/x86/kernel
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2018-05-21 11:23:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-05-21 11:23:26 -0700
commit3b78ce4a34b761c7fe13520de822984019ff1a8f (patch)
tree63b93664a184c2d561a70c7f8d16a388750739f7 /arch/x86/kernel
parent6741c4bb389da103c0d79ad1961884628900bfe6 (diff)
parentaf86ca4e3088fe5eacf2f7e58c01fa68ca067672 (diff)
Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Merge speculative store buffer bypass fixes from Thomas Gleixner: - rework of the SPEC_CTRL MSR management to accomodate the new fancy SSBD (Speculative Store Bypass Disable) bit handling. - the CPU bug and sysfs infrastructure for the exciting new Speculative Store Bypass 'feature'. - support for disabling SSB via LS_CFG MSR on AMD CPUs including Hyperthread synchronization on ZEN. - PRCTL support for dynamic runtime control of SSB - SECCOMP integration to automatically disable SSB for sandboxed processes with a filter flag for opt-out. - KVM integration to allow guests fiddling with SSBD including the new software MSR VIRT_SPEC_CTRL to handle the LS_CFG based oddities on AMD. - BPF protection against SSB .. this is just the core and x86 side, other architecture support will come separately. * 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits) bpf: Prevent memory disambiguation attack x86/bugs: Rename SSBD_NO to SSB_NO KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG x86/bugs: Rework spec_ctrl base and mask logic x86/bugs: Remove x86_spec_ctrl_set() x86/bugs: Expose x86_spec_ctrl_base directly x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host} x86/speculation: Rework speculative_store_bypass_update() x86/speculation: Add virtualized speculative store bypass disable support x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL x86/speculation: Handle HT correctly on AMD x86/cpufeatures: Add FEATURE_ZEN x86/cpufeatures: Disentangle SSBD enumeration x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP KVM: SVM: Move spec control call after restore of GS x86/cpu: Make alternative_msr_write work for 32-bit code x86/bugs: Fix the parameters alignment and missing void x86/bugs: Make cpu_show_common() static ...
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/amd.c22
-rw-r--r--arch/x86/kernel/cpu/bugs.c397
-rw-r--r--arch/x86/kernel/cpu/common.c77
-rw-r--r--arch/x86/kernel/cpu/cpu.h2
-rw-r--r--arch/x86/kernel/cpu/intel.c3
-rw-r--r--arch/x86/kernel/process.c146
-rw-r--r--arch/x86/kernel/smpboot.c5
7 files changed, 621 insertions, 31 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 12bc0a1139da..1b18be3f35a8 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -10,6 +10,7 @@
#include <asm/processor.h>
#include <asm/apic.h>
#include <asm/cpu.h>
+#include <asm/spec-ctrl.h>
#include <asm/smp.h>
#include <asm/pci-direct.h>
#include <asm/delay.h>
@@ -554,6 +555,26 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
rdmsrl(MSR_FAM10H_NODE_ID, value);
nodes_per_socket = ((value >> 3) & 7) + 1;
}
+
+ if (c->x86 >= 0x15 && c->x86 <= 0x17) {
+ unsigned int bit;
+
+ switch (c->x86) {
+ case 0x15: bit = 54; break;
+ case 0x16: bit = 33; break;
+ case 0x17: bit = 10; break;
+ default: return;
+ }
+ /*
+ * Try to cache the base value so further operations can
+ * avoid RMW. If that faults, do not enable SSBD.
+ */
+ if (!rdmsrl_safe(MSR_AMD64_LS_CFG, &x86_amd_ls_cfg_base)) {
+ setup_force_cpu_cap(X86_FEATURE_LS_CFG_SSBD);
+ setup_force_cpu_cap(X86_FEATURE_SSBD);
+ x86_amd_ls_cfg_ssbd_mask = 1ULL << bit;
+ }
+ }
}
static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
@@ -791,6 +812,7 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
static void init_amd_zn(struct cpuinfo_x86 *c)
{
+ set_cpu_cap(c, X86_FEATURE_ZEN);
/*
* Fix erratum 1076: CPB feature bit not being set in CPUID. It affects
* all up to and including B1.
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index bfca937bdcc3..7416fc206b4a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -12,8 +12,10 @@
#include <linux/utsname.h>
#include <linux/cpu.h>
#include <linux/module.h>
+#include <linux/nospec.h>
+#include <linux/prctl.h>
-#include <asm/nospec-branch.h>
+#include <asm/spec-ctrl.h>
#include <asm/cmdline.h>
#include <asm/bugs.h>
#include <asm/processor.h>
@@ -27,6 +29,27 @@
#include <asm/intel-family.h>
static void __init spectre_v2_select_mitigation(void);
+static void __init ssb_select_mitigation(void);
+
+/*
+ * Our boot-time value of the SPEC_CTRL MSR. We read it once so that any
+ * writes to SPEC_CTRL contain whatever reserved bits have been set.
+ */
+u64 __ro_after_init x86_spec_ctrl_base;
+EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
+
+/*
+ * The vendor and possibly platform specific bits which can be modified in
+ * x86_spec_ctrl_base.
+ */
+static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
+
+/*
+ * AMD specific MSR info for Speculative Store Bypass control.
+ * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
+ */
+u64 __ro_after_init x86_amd_ls_cfg_base;
+u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
void __init check_bugs(void)
{
@@ -37,9 +60,27 @@ void __init check_bugs(void)
print_cpu_info(&boot_cpu_data);
}
+ /*
+ * 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);
+
+ /* Allow STIBP in MSR_SPEC_CTRL if supported */
+ if (boot_cpu_has(X86_FEATURE_STIBP))
+ x86_spec_ctrl_mask |= SPEC_CTRL_STIBP;
+
/* Select the proper spectre mitigation before patching alternatives */
spectre_v2_select_mitigation();
+ /*
+ * Select proper mitigation for any exposure to the Speculative Store
+ * Bypass vulnerability.
+ */
+ ssb_select_mitigation();
+
#ifdef CONFIG_X86_32
/*
* Check whether we are able to run this kernel safely on SMP.
@@ -93,7 +134,76 @@ static const char *spectre_v2_strings[] = {
#undef pr_fmt
#define pr_fmt(fmt) "Spectre V2 : " fmt
-static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;
+static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
+ SPECTRE_V2_NONE;
+
+void
+x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
+{
+ u64 msrval, guestval, hostval = x86_spec_ctrl_base;
+ 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))
+ hostval |= ssbd_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.
+ */
+ if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
+ !static_cpu_has(X86_FEATURE_VIRT_SSBD))
+ return;
+
+ /*
+ * If the host has SSBD mitigation enabled, force it in the host's
+ * virtual MSR value. If its not permanently enabled, evaluate
+ * current's TIF_SSBD thread flag.
+ */
+ if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
+ hostval = SPEC_CTRL_SSBD;
+ else
+ hostval = ssbd_tif_to_spec_ctrl(ti->flags);
+
+ /* Sanitize the guest value */
+ guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
+
+ if (hostval != guestval) {
+ unsigned long tif;
+
+ tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
+ ssbd_spec_ctrl_to_tif(hostval);
+
+ speculative_store_bypass_update(tif);
+ }
+}
+EXPORT_SYMBOL_GPL(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);
+ else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
+ wrmsrl(MSR_AMD64_LS_CFG, msrval);
+}
#ifdef RETPOLINE
static bool spectre_v2_bad_module;
@@ -312,32 +422,289 @@ retpoline_auto:
}
#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 const char *ssb_strings[] = {
+ [SPEC_STORE_BYPASS_NONE] = "Vulnerable",
+ [SPEC_STORE_BYPASS_DISABLE] = "Mitigation: Speculative Store Bypass disabled",
+ [SPEC_STORE_BYPASS_PRCTL] = "Mitigation: Speculative Store Bypass disabled via prctl",
+ [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[] = {
+ { "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 enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
+{
+ 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")) {
+ 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;
+
+ for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
+ if (!match_option(arg, ret, ssb_mitigation_options[i].option))
+ continue;
+
+ cmd = ssb_mitigation_options[i].cmd;
+ break;
+ }
+
+ if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
+ pr_err("unknown option (%s). Switching to AUTO select\n", arg);
+ return SPEC_STORE_BYPASS_CMD_AUTO;
+ }
+ }
+
+ return cmd;
+}
+
+static enum ssb_mitigation __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;
+
+ 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;
+ 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;
+ }
+
+ /*
+ * 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) {
+ setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
+ /*
+ * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD uses
+ * a completely different MSR and bit dependent on family.
+ */
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_INTEL:
+ x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
+ x86_spec_ctrl_mask |= SPEC_CTRL_SSBD;
+ wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
+ break;
+ case X86_VENDOR_AMD:
+ x86_amd_ssb_disable();
+ break;
+ }
+ }
+
+ 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
+#define pr_fmt(fmt) "Speculation prctl: " fmt
+
+static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
+{
+ bool update;
+
+ if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
+ ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
+ return -ENXIO;
+
+ switch (ctrl) {
+ case PR_SPEC_ENABLE:
+ /* If speculation is force disabled, enable is not allowed */
+ if (task_spec_ssb_force_disable(task))
+ return -EPERM;
+ task_clear_spec_ssb_disable(task);
+ update = test_and_clear_tsk_thread_flag(task, TIF_SSBD);
+ break;
+ case PR_SPEC_DISABLE:
+ task_set_spec_ssb_disable(task);
+ update = !test_and_set_tsk_thread_flag(task, TIF_SSBD);
+ break;
+ case PR_SPEC_FORCE_DISABLE:
+ task_set_spec_ssb_disable(task);
+ task_set_spec_ssb_force_disable(task);
+ update = !test_and_set_tsk_thread_flag(task, TIF_SSBD);
+ break;
+ default:
+ return -ERANGE;
+ }
+
+ /*
+ * If being set on non-current task, delay setting the CPU
+ * mitigation until it is next scheduled.
+ */
+ if (task == current && update)
+ speculative_store_bypass_update_current();
+
+ return 0;
+}
+
+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
+ unsigned long ctrl)
+{
+ switch (which) {
+ case PR_SPEC_STORE_BYPASS:
+ return ssb_prctl_set(task, ctrl);
+ default:
+ return -ENODEV;
+ }
+}
+
+#ifdef CONFIG_SECCOMP
+void arch_seccomp_spec_mitigate(struct task_struct *task)
+{
+ if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
+ ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
+}
+#endif
+
+static int ssb_prctl_get(struct task_struct *task)
+{
+ switch (ssb_mode) {
+ case SPEC_STORE_BYPASS_DISABLE:
+ return PR_SPEC_DISABLE;
+ case SPEC_STORE_BYPASS_SECCOMP:
+ case SPEC_STORE_BYPASS_PRCTL:
+ if (task_spec_ssb_force_disable(task))
+ return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
+ 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;
+ }
+}
+
+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
+{
+ switch (which) {
+ case PR_SPEC_STORE_BYPASS:
+ return ssb_prctl_get(task);
+ default:
+ return -ENODEV;
+ }
+}
+
+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);
+
+ if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
+ x86_amd_ssb_disable();
+}
#ifdef CONFIG_SYSFS
-ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
+
+static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
+ char *buf, unsigned int bug)
{
- if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
+ if (!boot_cpu_has_bug(bug))
return sprintf(buf, "Not affected\n");
- if (boot_cpu_has(X86_FEATURE_PTI))
- return sprintf(buf, "Mitigation: PTI\n");
+
+ switch (bug) {
+ case X86_BUG_CPU_MELTDOWN:
+ if (boot_cpu_has(X86_FEATURE_PTI))
+ return sprintf(buf, "Mitigation: PTI\n");
+
+ break;
+
+ case X86_BUG_SPECTRE_V1:
+ return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+
+ case X86_BUG_SPECTRE_V2:
+ return sprintf(buf, "%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
+ boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
+ boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
+ spectre_v2_module_string());
+
+ case X86_BUG_SPEC_STORE_BYPASS:
+ return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);
+
+ default:
+ break;
+ }
+
return sprintf(buf, "Vulnerable\n");
}
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
+}
+
ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
{
- if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
- return sprintf(buf, "Not affected\n");
- return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+ return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
}
ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
{
- if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
- return sprintf(buf, "Not affected\n");
+ return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
+}
- return sprintf(buf, "%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
- boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
- boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
- spectre_v2_module_string());
+ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
}
#endif
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index ce243f7d2d4e..78decc3e3067 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -757,17 +757,32 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
* and they also have a different bit for STIBP support. Also,
* a hypervisor might have set the individual AMD bits even on
* Intel CPUs, for finer-grained selection of what's available.
- *
- * We use the AMD bits in 0x8000_0008 EBX as the generic hardware
- * features, which are visible in /proc/cpuinfo and used by the
- * kernel. So set those accordingly from the Intel bits.
*/
if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) {
set_cpu_cap(c, X86_FEATURE_IBRS);
set_cpu_cap(c, X86_FEATURE_IBPB);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
}
+
if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
set_cpu_cap(c, X86_FEATURE_STIBP);
+
+ if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD) ||
+ cpu_has(c, X86_FEATURE_VIRT_SSBD))
+ set_cpu_cap(c, X86_FEATURE_SSBD);
+
+ if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {
+ set_cpu_cap(c, X86_FEATURE_IBRS);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ }
+
+ if (cpu_has(c, X86_FEATURE_AMD_IBPB))
+ set_cpu_cap(c, X86_FEATURE_IBPB);
+
+ if (cpu_has(c, X86_FEATURE_AMD_STIBP)) {
+ set_cpu_cap(c, X86_FEATURE_STIBP);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ }
}
void get_cpu_cap(struct cpuinfo_x86 *c)
@@ -927,21 +942,55 @@ static const __initconst struct x86_cpu_id cpu_no_meltdown[] = {
{}
};
-static bool __init cpu_vulnerable_to_meltdown(struct cpuinfo_x86 *c)
+static const __initconst struct x86_cpu_id cpu_no_spec_store_bypass[] = {
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT1 },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_AIRMONT },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT2 },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_MERRIFIELD },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_CORE_YONAH },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNL },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNM },
+ { X86_VENDOR_CENTAUR, 5, },
+ { X86_VENDOR_INTEL, 5, },
+ { X86_VENDOR_NSC, 5, },
+ { X86_VENDOR_AMD, 0x12, },
+ { X86_VENDOR_AMD, 0x11, },
+ { X86_VENDOR_AMD, 0x10, },
+ { X86_VENDOR_AMD, 0xf, },
+ { X86_VENDOR_ANY, 4, },
+ {}
+};
+
+static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
{
u64 ia32_cap = 0;
- if (x86_match_cpu(cpu_no_meltdown))
- return false;
-
if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
+ if (!x86_match_cpu(cpu_no_spec_store_bypass) &&
+ !(ia32_cap & ARCH_CAP_SSB_NO))
+ setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
+
+ if (x86_match_cpu(cpu_no_speculation))
+ return;
+
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+
+ if (x86_match_cpu(cpu_no_meltdown))
+ return;
+
/* Rogue Data Cache Load? No! */
if (ia32_cap & ARCH_CAP_RDCL_NO)
- return false;
+ return;
- return true;
+ setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
}
/*
@@ -992,12 +1041,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
- if (!x86_match_cpu(cpu_no_speculation)) {
- if (cpu_vulnerable_to_meltdown(c))
- setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
- setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
- setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
- }
+ cpu_set_bug_bits(c);
fpu__init_system(c);
@@ -1359,6 +1403,7 @@ void identify_secondary_cpu(struct cpuinfo_x86 *c)
#endif
mtrr_ap_init();
validate_apic_and_package_id(c);
+ x86_spec_ctrl_setup_ap();
}
static __init int setup_noclflush(char *arg)
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index e806b11a99af..37672d299e35 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -50,4 +50,6 @@ extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
unsigned int aperfmperf_get_khz(int cpu);
+extern void x86_spec_ctrl_setup_ap(void);
+
#endif /* ARCH_X86_CPU_H */
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 60d1897041da..577e7f7ae273 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -188,7 +188,10 @@ static void early_init_intel(struct cpuinfo_x86 *c)
setup_clear_cpu_cap(X86_FEATURE_IBPB);
setup_clear_cpu_cap(X86_FEATURE_STIBP);
setup_clear_cpu_cap(X86_FEATURE_SPEC_CTRL);
+ setup_clear_cpu_cap(X86_FEATURE_MSR_SPEC_CTRL);
setup_clear_cpu_cap(X86_FEATURE_INTEL_STIBP);
+ setup_clear_cpu_cap(X86_FEATURE_SSBD);
+ setup_clear_cpu_cap(X86_FEATURE_SPEC_CTRL_SSBD);
}
/*
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 03408b942adb..30ca2d1a9231 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -38,6 +38,7 @@
#include <asm/switch_to.h>
#include <asm/desc.h>
#include <asm/prctl.h>
+#include <asm/spec-ctrl.h>
/*
* per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -278,6 +279,148 @@ static inline void switch_to_bitmap(struct tss_struct *tss,
}
}
+#ifdef CONFIG_SMP
+
+struct ssb_state {
+ struct ssb_state *shared_state;
+ raw_spinlock_t lock;
+ unsigned int disable_state;
+ unsigned long local_state;
+};
+
+#define LSTATE_SSB 0
+
+static DEFINE_PER_CPU(struct ssb_state, ssb_state);
+
+void speculative_store_bypass_ht_init(void)
+{
+ struct ssb_state *st = this_cpu_ptr(&ssb_state);
+ unsigned int this_cpu = smp_processor_id();
+ unsigned int cpu;
+
+ st->local_state = 0;
+
+ /*
+ * Shared state setup happens once on the first bringup
+ * of the CPU. It's not destroyed on CPU hotunplug.
+ */
+ if (st->shared_state)
+ return;
+
+ raw_spin_lock_init(&st->lock);
+
+ /*
+ * Go over HT siblings and check whether one of them has set up the
+ * shared state pointer already.
+ */
+ for_each_cpu(cpu, topology_sibling_cpumask(this_cpu)) {
+ if (cpu == this_cpu)
+ continue;
+
+ if (!per_cpu(ssb_state, cpu).shared_state)
+ continue;
+
+ /* Link it to the state of the sibling: */
+ st->shared_state = per_cpu(ssb_state, cpu).shared_state;
+ return;
+ }
+
+ /*
+ * First HT sibling to come up on the core. Link shared state of
+ * the first HT sibling to itself. The siblings on the same core
+ * which come up later will see the shared state pointer and link
+ * themself to the state of this CPU.
+ */
+ st->shared_state = st;
+}
+
+/*
+ * Logic is: First HT sibling enables SSBD for both siblings in the core
+ * and last sibling to disable it, disables it for the whole core. This how
+ * MSR_SPEC_CTRL works in "hardware":
+ *
+ * CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL
+ */
+static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
+{
+ struct ssb_state *st = this_cpu_ptr(&ssb_state);
+ u64 msr = x86_amd_ls_cfg_base;
+
+ if (!static_cpu_has(X86_FEATURE_ZEN)) {
+ msr |= ssbd_tif_to_amd_ls_cfg(tifn);
+ wrmsrl(MSR_AMD64_LS_CFG, msr);
+ return;
+ }
+
+ if (tifn & _TIF_SSBD) {
+ /*
+ * Since this can race with prctl(), block reentry on the
+ * same CPU.
+ */
+ if (__test_and_set_bit(LSTATE_SSB, &st->local_state))
+ return;
+
+ msr |= x86_amd_ls_cfg_ssbd_mask;
+
+ raw_spin_lock(&st->shared_state->lock);
+ /* First sibling enables SSBD: */
+ if (!st->shared_state->disable_state)
+ wrmsrl(MSR_AMD64_LS_CFG, msr);
+ st->shared_state->disable_state++;
+ raw_spin_unlock(&st->shared_state->lock);
+ } else {
+ if (!__test_and_clear_bit(LSTATE_SSB, &st->local_state))
+ return;
+
+ raw_spin_lock(&st->shared_state->lock);
+ st->shared_state->disable_state--;
+ if (!st->shared_state->disable_state)
+ wrmsrl(MSR_AMD64_LS_CFG, msr);
+ raw_spin_unlock(&st->shared_state->lock);
+ }
+}
+#else
+static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
+{
+ u64 msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn);
+
+ wrmsrl(MSR_AMD64_LS_CFG, msr);
+}
+#endif
+
+static __always_inline void amd_set_ssb_virt_state(unsigned long tifn)
+{
+ /*
+ * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL,
+ * so ssbd_tif_to_spec_ctrl() just works.
+ */
+ wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn));
+}
+
+static __always_inline void intel_set_ssb_state(unsigned long tifn)
+{
+ u64 msr = x86_spec_ctrl_base | ssbd_tif_to_spec_ctrl(tifn);
+
+ wrmsrl(MSR_IA32_SPEC_CTRL, msr);
+}
+
+static __always_inline void __speculative_store_bypass_update(unsigned long tifn)
+{
+ if (static_cpu_has(X86_FEATURE_VIRT_SSBD))
+ amd_set_ssb_virt_state(tifn);
+ else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD))
+ amd_set_core_ssb_state(tifn);
+ else
+ intel_set_ssb_state(tifn);
+}
+
+void speculative_store_bypass_update(unsigned long tif)
+{
+ preempt_disable();
+ __speculative_store_bypass_update(tif);
+ preempt_enable();
+}
+
void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
struct tss_struct *tss)
{
@@ -309,6 +452,9 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
if ((tifp ^ tifn) & _TIF_NOCPUID)
set_cpuid_faulting(!!(tifn & _TIF_NOCPUID));
+
+ if ((tifp ^ tifn) & _TIF_SSBD)
+ __speculative_store_bypass_update(tifn);
}
/*
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 0f1cbb042f49..9dd324ae4832 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -79,6 +79,7 @@
#include <asm/qspinlock.h>
#include <asm/intel-family.h>
#include <asm/cpu_device_id.h>
+#include <asm/spec-ctrl.h>
/* Number of siblings per CPU package */
int smp_num_siblings = 1;
@@ -244,6 +245,8 @@ static void notrace start_secondary(void *unused)
*/
check_tsc_sync_target();
+ speculative_store_bypass_ht_init();
+
/*
* Lock vector_lock, set CPU online and bring the vector
* allocator online. Online must be set with vector_lock held
@@ -1292,6 +1295,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
set_mtrr_aps_delayed_init();
smp_quirk_init_udelay();
+
+ speculative_store_bypass_ht_init();
}
void arch_enable_nonboot_cpus_begin(void)