diff options
Diffstat (limited to 'arch/arm64/kvm')
| -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 |
3 files changed, 85 insertions, 16 deletions
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 }, |