diff options
| -rw-r--r-- | arch/arm/include/asm/kvm_emulate.h | 2 | ||||
| -rw-r--r-- | arch/arm64/Kconfig | 6 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_emulate.h | 16 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 14 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_ptrauth.h | 111 | ||||
| -rw-r--r-- | arch/arm64/kernel/asm-offsets.c | 6 | ||||
| -rw-r--r-- | arch/arm64/kvm/handle_exit.c | 36 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/entry.S | 15 | ||||
| -rw-r--r-- | arch/arm64/kvm/sys_regs.c | 50 | ||||
| -rw-r--r-- | virt/kvm/arm/arm.c | 2 |
10 files changed, 240 insertions, 18 deletions
diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h index 8927cae7c966..efb0e2c0d84c 100644 --- a/arch/arm/include/asm/kvm_emulate.h +++ b/arch/arm/include/asm/kvm_emulate.h @@ -343,4 +343,6 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu, } } +static inline void vcpu_ptrauth_setup_lazy(struct kvm_vcpu *vcpu) {} + #endif /* __ARM_KVM_EMULATE_H__ */ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7e34b9eba5de..39470784a50c 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1288,6 +1288,7 @@ menu "ARMv8.3 architectural features" config ARM64_PTR_AUTH bool "Enable support for pointer authentication" default y + depends on !KVM || ARM64_VHE help Pointer authentication (part of the ARMv8.3 Extensions) provides instructions for signing and authenticating pointers against secret @@ -1301,8 +1302,9 @@ config ARM64_PTR_AUTH context-switched along with the process. The feature is detected at runtime. If the feature is not present in - hardware it will not be advertised to userspace nor will it be - enabled. + hardware it will not be advertised to userspace/KVM guest nor will it + be enabled. However, KVM guest also require VHE mode and hence + CONFIG_ARM64_VHE=y option to use this feature. endmenu diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index d3842791e1c4..613427fafff9 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -98,6 +98,22 @@ static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu) vcpu->arch.hcr_el2 |= HCR_TWE; } +static inline void vcpu_ptrauth_enable(struct kvm_vcpu *vcpu) +{ + vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK); +} + +static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu) +{ + vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK); +} + +static inline void vcpu_ptrauth_setup_lazy(struct kvm_vcpu *vcpu) +{ + if (vcpu_has_ptrauth(vcpu)) + vcpu_ptrauth_disable(vcpu); +} + static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu) { return vcpu->arch.vsesr_el2; diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 7ccac42a91a6..7eebea7059c6 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -161,6 +161,18 @@ enum vcpu_sysreg { PMSWINC_EL0, /* Software Increment Register */ PMUSERENR_EL0, /* User Enable Register */ + /* Pointer Authentication Registers in a strict increasing order. */ + APIAKEYLO_EL1, + APIAKEYHI_EL1, + APIBKEYLO_EL1, + APIBKEYHI_EL1, + APDAKEYLO_EL1, + APDAKEYHI_EL1, + APDBKEYLO_EL1, + APDBKEYHI_EL1, + APGAKEYLO_EL1, + APGAKEYHI_EL1, + /* 32bit specific registers. Keep them at the end of the range */ DACR32_EL2, /* Domain Access Control Register */ IFSR32_EL2, /* Instruction Fault Status Register */ @@ -530,6 +542,8 @@ static inline bool kvm_arch_requires_vhe(void) return false; } +void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu); + static inline void kvm_arch_hardware_unsetup(void) {} static inline void kvm_arch_sync_events(struct kvm *kvm) {} static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} diff --git a/arch/arm64/include/asm/kvm_ptrauth.h b/arch/arm64/include/asm/kvm_ptrauth.h new file mode 100644 index 000000000000..6301813dcace --- /dev/null +++ b/arch/arm64/include/asm/kvm_ptrauth.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* arch/arm64/include/asm/kvm_ptrauth.h: Guest/host ptrauth save/restore + * Copyright 2019 Arm Limited + * Authors: Mark Rutland <mark.rutland@arm.com> + * Amit Daniel Kachhap <amit.kachhap@arm.com> + */ + +#ifndef __ASM_KVM_PTRAUTH_H +#define __ASM_KVM_PTRAUTH_H + +#ifdef __ASSEMBLY__ + +#include <asm/sysreg.h> + +#ifdef CONFIG_ARM64_PTR_AUTH + +#define PTRAUTH_REG_OFFSET(x) (x - CPU_APIAKEYLO_EL1) + +/* + * CPU_AP*_EL1 values exceed immediate offset range (512) for stp + * instruction so below macros takes CPU_APIAKEYLO_EL1 as base and + * calculates the offset of the keys from this base to avoid an extra add + * instruction. These macros assumes the keys offsets follow the order of + * the sysreg enum in kvm_host.h. + */ +.macro ptrauth_save_state base, reg1, reg2 + mrs_s \reg1, SYS_APIAKEYLO_EL1 + mrs_s \reg2, SYS_APIAKEYHI_EL1 + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIAKEYLO_EL1)] + mrs_s \reg1, SYS_APIBKEYLO_EL1 + mrs_s \reg2, SYS_APIBKEYHI_EL1 + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIBKEYLO_EL1)] + mrs_s \reg1, SYS_APDAKEYLO_EL1 + mrs_s \reg2, SYS_APDAKEYHI_EL1 + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDAKEYLO_EL1)] + mrs_s \reg1, SYS_APDBKEYLO_EL1 + mrs_s \reg2, SYS_APDBKEYHI_EL1 + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDBKEYLO_EL1)] + mrs_s \reg1, SYS_APGAKEYLO_EL1 + mrs_s \reg2, SYS_APGAKEYHI_EL1 + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APGAKEYLO_EL1)] +.endm + +.macro ptrauth_restore_state base, reg1, reg2 + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIAKEYLO_EL1)] + msr_s SYS_APIAKEYLO_EL1, \reg1 + msr_s SYS_APIAKEYHI_EL1, \reg2 + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIBKEYLO_EL1)] + msr_s SYS_APIBKEYLO_EL1, \reg1 + msr_s SYS_APIBKEYHI_EL1, \reg2 + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDAKEYLO_EL1)] + msr_s SYS_APDAKEYLO_EL1, \reg1 + msr_s SYS_APDAKEYHI_EL1, \reg2 + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDBKEYLO_EL1)] + msr_s SYS_APDBKEYLO_EL1, \reg1 + msr_s SYS_APDBKEYHI_EL1, \reg2 + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APGAKEYLO_EL1)] + msr_s SYS_APGAKEYLO_EL1, \reg1 + msr_s SYS_APGAKEYHI_EL1, \reg2 +.endm + +/* + * Both ptrauth_switch_to_guest and ptrauth_switch_to_host macros will + * check for the presence of one of the cpufeature flag + * ARM64_HAS_ADDRESS_AUTH_ARCH or ARM64_HAS_ADDRESS_AUTH_IMP_DEF and + * then proceed ahead with the save/restore of Pointer Authentication + * key registers. + */ +.macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3 +alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH + b 1000f +alternative_else_nop_endif +alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF + b 1001f +alternative_else_nop_endif +1000: + ldr \reg1, [\g_ctxt, #(VCPU_HCR_EL2 - VCPU_CONTEXT)] + and \reg1, \reg1, #(HCR_API | HCR_APK) + cbz \reg1, 1001f + add \reg1, \g_ctxt, #CPU_APIAKEYLO_EL1 + ptrauth_restore_state \reg1, \reg2, \reg3 +1001: +.endm + +.macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3 +alternative_if ARM64_HAS_ADDRESS_AUTH_ARCH + b 2000f +alternative_else_nop_endif +alternative_if_not ARM64_HAS_ADDRESS_AUTH_IMP_DEF + b 2001f +alternative_else_nop_endif +2000: + ldr \reg1, [\g_ctxt, #(VCPU_HCR_EL2 - VCPU_CONTEXT)] + and \reg1, \reg1, #(HCR_API | HCR_APK) + cbz \reg1, 2001f + add \reg1, \g_ctxt, #CPU_APIAKEYLO_EL1 + ptrauth_save_state \reg1, \reg2, \reg3 + add \reg1, \h_ctxt, #CPU_APIAKEYLO_EL1 + ptrauth_restore_state \reg1, \reg2, \reg3 + isb +2001: +.endm + +#else /* !CONFIG_ARM64_PTR_AUTH */ +.macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3 +.endm +.macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3 +.endm +#endif /* CONFIG_ARM64_PTR_AUTH */ +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_KVM_PTRAUTH_H */ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 7f40dcbdd51d..8178330a9f7a 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -125,7 +125,13 @@ int main(void) DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt)); DEFINE(VCPU_FAULT_DISR, offsetof(struct kvm_vcpu, arch.fault.disr_el1)); DEFINE(VCPU_WORKAROUND_FLAGS, offsetof(struct kvm_vcpu, arch.workaround_flags)); + DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2)); DEFINE(CPU_GP_REGS, offsetof(struct kvm_cpu_context, gp_regs)); + DEFINE(CPU_APIAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIAKEYLO_EL1])); + DEFINE(CPU_APIBKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APIBKEYLO_EL1])); + DEFINE(CPU_APDAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APDAKEYLO_EL1])); + DEFINE(CPU_APDBKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APDBKEYLO_EL1])); + DEFINE(CPU_APGAKEYLO_EL1, offsetof(struct kvm_cpu_context, sys_regs[APGAKEYLO_EL1])); DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_regs, regs)); DEFINE(HOST_CONTEXT_VCPU, offsetof(struct kvm_cpu_context, __hyp_running_vcpu)); #endif diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 0b7983442071..516aead3c2a9 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -173,20 +173,40 @@ static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } +#define __ptrauth_save_key(regs, key) \ +({ \ + regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \ + regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \ +}) + +/* + * Handle the guest trying to use a ptrauth instruction, or trying to access a + * ptrauth register. + */ +void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu) +{ + struct kvm_cpu_context *ctxt; + + if (vcpu_has_ptrauth(vcpu)) { + vcpu_ptrauth_enable(vcpu); + ctxt = vcpu->arch.host_cpu_context; + __ptrauth_save_key(ctxt->sys_regs, APIA); + __ptrauth_save_key(ctxt->sys_regs, APIB); + __ptrauth_save_key(ctxt->sys_regs, APDA); + __ptrauth_save_key(ctxt->sys_regs, APDB); + __ptrauth_save_key(ctxt->sys_regs, APGA); + } else { + kvm_inject_undefined(vcpu); + } +} + /* * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into * a NOP). */ static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu, struct kvm_run *run) { - /* - * We don't currently support ptrauth in a guest, and we mask the ID - * registers to prevent well-behaved guests from trying to make use of - * it. - * - * Inject an UNDEF, as if the feature really isn't present. - */ - kvm_inject_undefined(vcpu); + kvm_arm_vcpu_ptrauth_trap(vcpu); return 1; } diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 675fdc186e3b..93ba3d7ef027 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -24,6 +24,7 @@ #include <asm/kvm_arm.h> #include <asm/kvm_asm.h> #include <asm/kvm_mmu.h> +#include <asm/kvm_ptrauth.h> #define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x) #define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x) @@ -64,6 +65,13 @@ ENTRY(__guest_enter) add x18, x0, #VCPU_CONTEXT + // Macro ptrauth_switch_to_guest format: + // ptrauth_switch_to_guest(guest cxt, tmp1, tmp2, tmp3) + // The below macro to restore guest keys is not implemented in C code + // as it may cause Pointer Authentication key signing mismatch errors + // when this feature is enabled for kernel code. + ptrauth_switch_to_guest x18, x0, x1, x2 + // Restore guest regs x0-x17 ldp x0, x1, [x18, #CPU_XREG_OFFSET(0)] ldp x2, x3, [x18, #CPU_XREG_OFFSET(2)] @@ -118,6 +126,13 @@ ENTRY(__guest_exit) get_host_ctxt x2, x3 + // Macro ptrauth_switch_to_guest format: + // ptrauth_switch_to_host(guest cxt, host cxt, tmp1, tmp2, tmp3) + // The below macro to save/restore keys is not implemented in C code + // as it may cause Pointer Authentication key signing mismatch errors + // when this feature is enabled for kernel code. + ptrauth_switch_to_host x1, x2, x3, x4, x5 + // Now restore the host regs restore_callee_saved_regs x2 diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 7046c7686321..12bd72e42b91 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1007,6 +1007,37 @@ static bool access_pmuserenr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, { SYS_DESC(SYS_PMEVTYPERn_EL0(n)), \ access_pmu_evtyper, reset_unknown, (PMEVTYPER0_EL0 + n), } +static bool trap_ptrauth(struct kvm_vcpu *vcpu, + struct sys_reg_params *p, + const struct sys_reg_desc *rd) +{ + kvm_arm_vcpu_ptrauth_trap(vcpu); + + /* + * Return false for both cases as we never skip the trapped + * instruction: + * + * - Either we re-execute the same key register access instruction + * after enabling ptrauth. + * - Or an UNDEF is injected as ptrauth is not supported/enabled. + */ + return false; +} + +static unsigned int ptrauth_visibility(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd) +{ + return vcpu_has_ptrauth(vcpu) ? 0 : REG_HIDDEN_USER | REG_HIDDEN_GUEST; +} + +#define __PTRAUTH_KEY(k) \ + { SYS_DESC(SYS_## k), trap_ptrauth, reset_unknown, k, \ + .visibility = ptrauth_visibility} + +#define PTRAUTH_KEY(k) \ + __PTRAUTH_KEY(k ## KEYLO_EL1), \ + __PTRAUTH_KEY(k ## KEYHI_EL1) + static bool access_arch_timer(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) @@ -1053,14 +1084,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, if (id == SYS_ID_AA64PFR0_EL1 && !vcpu_has_sve(vcpu)) { val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); - } else if (id == SYS_ID_AA64ISAR1_EL1) { - const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) | - (0xfUL << ID_AA64ISAR1_API_SHIFT) | - (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | - (0xfUL << ID_AA64ISAR1_GPI_SHIFT); - if (val & ptrauth_mask) - kvm_debug("ptrauth unsupported for guests, suppressing\n"); - val &= ~ptrauth_mask; + } else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { + val &= ~(0xfUL << ID_AA64ISAR1_APA_SHIFT) | + (0xfUL << ID_AA64ISAR1_API_SHIFT) | + (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | + (0xfUL << ID_AA64ISAR1_GPI_SHIFT); } return val; @@ -1460,6 +1488,12 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 }, { SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 }, + PTRAUTH_KEY(APIA), + PTRAUTH_KEY(APIB), + PTRAUTH_KEY(APDA), + PTRAUTH_KEY(APDB), + PTRAUTH_KEY(APGA), + { SYS_DESC(SYS_AFSR0_EL1), access_vm_reg, reset_unknown, AFSR0_EL1 }, { SYS_DESC(SYS_AFSR1_EL1), access_vm_reg, reset_unknown, AFSR1_EL1 }, { SYS_DESC(SYS_ESR_EL1), access_vm_reg, reset_unknown, ESR_EL1 }, diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 7039c99cc217..156c09da9e2b 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -385,6 +385,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vcpu_clear_wfe_traps(vcpu); else vcpu_set_wfe_traps(vcpu); + + vcpu_ptrauth_setup_lazy(vcpu); } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) |