diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-08-25 10:01:36 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-10-05 01:19:32 +0300 |
| commit | e47d86083c66525b89c7fc66cdd64d5937725563 (patch) | |
| tree | c7a2a4b5ef893299a54ced0955ac5406f6011777 /arch/x86 | |
| parent | 6f0f23ef76be11bc6ace10df5e807f3542da8772 (diff) | |
| download | linux-e47d86083c66525b89c7fc66cdd64d5937725563.tar.xz | |
KVM: x86: Add SBPB support
Add support for the AMD Selective Branch Predictor Barrier (SBPB) by
advertising the CPUID bit and handling PRED_CMD writes accordingly.
Note, like SRSO_NO and IBPB_BRTYPE before it, advertise support for SBPB
even if it's not enumerated by in the raw CPUID. Some CPUs that gained
support via a uCode patch don't report SBPB via CPUID (the kernel forces
the flag).
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/a4ab1e7fe50096d50fde33e739ed2da40b41ea6a.1692919072.git.jpoimboe@kernel.org
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/cpuid.h | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 29 |
3 files changed, 27 insertions, 6 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 8f26a929d510..552dc4f3899b 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -764,6 +764,7 @@ void kvm_set_cpu_caps(void) F(NULL_SEL_CLR_BASE) | F(AUTOIBRS) | 0 /* PrefetchCtlMsr */ ); + kvm_cpu_cap_check_and_set(X86_FEATURE_SBPB); kvm_cpu_cap_check_and_set(X86_FEATURE_IBPB_BRTYPE); kvm_cpu_cap_check_and_set(X86_FEATURE_SRSO_NO); diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 284fa4704553..0b90532b6e26 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -174,7 +174,8 @@ static inline bool guest_has_spec_ctrl_msr(struct kvm_vcpu *vcpu) static inline bool guest_has_pred_cmd_msr(struct kvm_vcpu *vcpu) { return (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) || - guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB)); + guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB) || + guest_cpuid_has(vcpu, X86_FEATURE_SBPB)); } static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ec728aef9acc..2b5b325e19f2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3670,17 +3670,36 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.perf_capabilities = data; kvm_pmu_refresh(vcpu); break; - case MSR_IA32_PRED_CMD: - if (!msr_info->host_initiated && !guest_has_pred_cmd_msr(vcpu)) - return 1; + case MSR_IA32_PRED_CMD: { + u64 reserved_bits = ~(PRED_CMD_IBPB | PRED_CMD_SBPB); + + if (!msr_info->host_initiated) { + if ((!guest_has_pred_cmd_msr(vcpu))) + return 1; + + if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) && + !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB)) + reserved_bits |= PRED_CMD_IBPB; - if (!boot_cpu_has(X86_FEATURE_IBPB) || (data & ~PRED_CMD_IBPB)) + if (!guest_cpuid_has(vcpu, X86_FEATURE_SBPB)) + reserved_bits |= PRED_CMD_SBPB; + } + + if (!boot_cpu_has(X86_FEATURE_IBPB)) + reserved_bits |= PRED_CMD_IBPB; + + if (!boot_cpu_has(X86_FEATURE_SBPB)) + reserved_bits |= PRED_CMD_SBPB; + + if (data & reserved_bits) return 1; + if (!data) break; - wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB); + wrmsrl(MSR_IA32_PRED_CMD, data); break; + } case MSR_IA32_FLUSH_CMD: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_FLUSH_L1D)) |