| Message ID | 20240410143446.797262-8-chao.gao@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Virtualize Intel IA32_SPEC_CTRL | expand |
On Wed, Apr 10, 2024 at 8:08 AM Chao Gao <chao.gao@intel.com> wrote: > > From: Zhang Chen <chen.zhang@intel.com> > > Bit 63 of IA32_ARCH_CAPABILITIES MSR indicates availablility of the > VIRTUAL_ENUMERATION_MSR (index 0x50000000) which enumerates features > like e.g., mitigation enumeration that in turn is used for the guest to > report software mitigations it is using. > > Advertise ARCH_CAP_VIRTUAL_ENUM support for VMX and emulate read/write > of the VIRTUAL_ENUMERATION_MSR. Now VIRTUAL_ENUMERATION_MSR is always 0. > > Signed-off-by: Zhang Chen <chen.zhang@intel.com> > Co-developed-by: Chao Gao <chao.gao@intel.com> > Signed-off-by: Chao Gao <chao.gao@intel.com> > --- > arch/x86/kvm/svm/svm.c | 1 + > arch/x86/kvm/vmx/vmx.c | 19 +++++++++++++++++++ > arch/x86/kvm/vmx/vmx.h | 2 ++ > arch/x86/kvm/x86.c | 16 +++++++++++++++- > 4 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index d1a9f9951635..e3406971a8b7 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -4288,6 +4288,7 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index) > { > switch (index) { > case MSR_IA32_MCG_EXT_CTL: > + case MSR_VIRTUAL_ENUMERATION: > case KVM_FIRST_EMULATED_VMX_MSR ... KVM_LAST_EMULATED_VMX_MSR: > return false; > case MSR_IA32_SMBASE: > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index cdfcc1290d82..dcb06406fd09 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -1955,6 +1955,8 @@ static inline bool is_vmx_feature_control_msr_valid(struct vcpu_vmx *vmx, > return !(msr->data & ~valid_bits); > } > > +#define VIRTUAL_ENUMERATION_VALID_BITS 0ULL > + > static int vmx_get_msr_feature(struct kvm_msr_entry *msr) > { > switch (msr->index) { > @@ -1962,6 +1964,9 @@ static int vmx_get_msr_feature(struct kvm_msr_entry *msr) > if (!nested) > return 1; > return vmx_get_vmx_msr(&vmcs_config.nested, msr->index, &msr->data); > + case MSR_VIRTUAL_ENUMERATION: > + msr->data = VIRTUAL_ENUMERATION_VALID_BITS; > + return 0; > default: > return KVM_MSR_RET_INVALID; > } > @@ -2113,6 +2118,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > case MSR_IA32_DEBUGCTLMSR: > msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL); > break; > + case MSR_VIRTUAL_ENUMERATION: > + if (!msr_info->host_initiated && > + !(vcpu->arch.arch_capabilities & ARCH_CAP_VIRTUAL_ENUM)) > + return 1; > + msr_info->data = vmx->msr_virtual_enumeration; > + break; > default: > find_uret_msr: > msr = vmx_find_uret_msr(vmx, msr_info->index); > @@ -2457,6 +2468,14 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > } > ret = kvm_set_msr_common(vcpu, msr_info); > break; > + case MSR_VIRTUAL_ENUMERATION: > + if (!msr_info->host_initiated) > + return 1; > + if (data & ~VIRTUAL_ENUMERATION_VALID_BITS) > + return 1; > + > + vmx->msr_virtual_enumeration = data; > + break; > > default: > find_uret_msr: > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index a4dfe538e5a8..0519cf6187ac 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -294,6 +294,8 @@ struct vcpu_vmx { > u64 force_spec_ctrl_mask; > u64 force_spec_ctrl_value; > > + u64 msr_virtual_enumeration; > + > u32 msr_ia32_umwait_control; > > /* > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 9a59b5a93d0e..4721b6fe7641 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1564,6 +1564,7 @@ static const u32 emulated_msrs_all[] = { > > MSR_K7_HWCR, > MSR_KVM_POLL_CONTROL, > + MSR_VIRTUAL_ENUMERATION, > }; > > static u32 emulated_msrs[ARRAY_SIZE(emulated_msrs_all)]; > @@ -1579,6 +1580,7 @@ static const u32 msr_based_features_all_except_vmx[] = { > MSR_IA32_UCODE_REV, > MSR_IA32_ARCH_CAPABILITIES, > MSR_IA32_PERF_CAPABILITIES, > + MSR_VIRTUAL_ENUMERATION, > }; > > static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all_except_vmx) + > @@ -1621,7 +1623,8 @@ static bool kvm_is_immutable_feature_msr(u32 msr) > ARCH_CAP_PSCHANGE_MC_NO | ARCH_CAP_TSX_CTRL_MSR | ARCH_CAP_TAA_NO | \ > ARCH_CAP_SBDR_SSDP_NO | ARCH_CAP_FBSDP_NO | ARCH_CAP_PSDP_NO | \ > ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO | ARCH_CAP_GDS_NO | \ > - ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR | ARCH_CAP_BHI_NO) > + ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR | ARCH_CAP_BHI_NO | \ > + ARCH_CAP_VIRTUAL_ENUM) > > static u64 kvm_get_arch_capabilities(void) > { > @@ -1635,6 +1638,17 @@ static u64 kvm_get_arch_capabilities(void) > */ > data |= ARCH_CAP_PSCHANGE_MC_NO; > > + /* > + * Virtual enumeration is a paravirt feature. The only usage for now > + * is to bridge the gap caused by microarchitecture changes between > + * different Intel processors. And its usage is linked to "virtualize > + * IA32_SPEC_CTRL" which is a VMX feature. Whether AMD SVM can benefit > + * from the same usage and how to implement it is still unclear. Limit > + * virtual enumeration to VMX. > + */ Virtualize IA32_SPEC_CTRL has been an SVM feature for years. See https://lore.kernel.org/kvm/160738054169.28590.5171339079028237631.stgit@bmoger-ubuntu/. > + if (static_call(kvm_x86_has_emulated_msr)(NULL, MSR_VIRTUAL_ENUMERATION)) > + data |= ARCH_CAP_VIRTUAL_ENUM; > + > /* > * If we're doing cache flushes (either "always" or "cond") > * we will do one whenever the guest does a vmlaunch/vmresume. > -- > 2.39.3 > >
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index d1a9f9951635..e3406971a8b7 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4288,6 +4288,7 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index) { switch (index) { case MSR_IA32_MCG_EXT_CTL: + case MSR_VIRTUAL_ENUMERATION: case KVM_FIRST_EMULATED_VMX_MSR ... KVM_LAST_EMULATED_VMX_MSR: return false; case MSR_IA32_SMBASE: diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index cdfcc1290d82..dcb06406fd09 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1955,6 +1955,8 @@ static inline bool is_vmx_feature_control_msr_valid(struct vcpu_vmx *vmx, return !(msr->data & ~valid_bits); } +#define VIRTUAL_ENUMERATION_VALID_BITS 0ULL + static int vmx_get_msr_feature(struct kvm_msr_entry *msr) { switch (msr->index) { @@ -1962,6 +1964,9 @@ static int vmx_get_msr_feature(struct kvm_msr_entry *msr) if (!nested) return 1; return vmx_get_vmx_msr(&vmcs_config.nested, msr->index, &msr->data); + case MSR_VIRTUAL_ENUMERATION: + msr->data = VIRTUAL_ENUMERATION_VALID_BITS; + return 0; default: return KVM_MSR_RET_INVALID; } @@ -2113,6 +2118,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_IA32_DEBUGCTLMSR: msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL); break; + case MSR_VIRTUAL_ENUMERATION: + if (!msr_info->host_initiated && + !(vcpu->arch.arch_capabilities & ARCH_CAP_VIRTUAL_ENUM)) + return 1; + msr_info->data = vmx->msr_virtual_enumeration; + break; default: find_uret_msr: msr = vmx_find_uret_msr(vmx, msr_info->index); @@ -2457,6 +2468,14 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) } ret = kvm_set_msr_common(vcpu, msr_info); break; + case MSR_VIRTUAL_ENUMERATION: + if (!msr_info->host_initiated) + return 1; + if (data & ~VIRTUAL_ENUMERATION_VALID_BITS) + return 1; + + vmx->msr_virtual_enumeration = data; + break; default: find_uret_msr: diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index a4dfe538e5a8..0519cf6187ac 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -294,6 +294,8 @@ struct vcpu_vmx { u64 force_spec_ctrl_mask; u64 force_spec_ctrl_value; + u64 msr_virtual_enumeration; + u32 msr_ia32_umwait_control; /* diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9a59b5a93d0e..4721b6fe7641 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1564,6 +1564,7 @@ static const u32 emulated_msrs_all[] = { MSR_K7_HWCR, MSR_KVM_POLL_CONTROL, + MSR_VIRTUAL_ENUMERATION, }; static u32 emulated_msrs[ARRAY_SIZE(emulated_msrs_all)]; @@ -1579,6 +1580,7 @@ static const u32 msr_based_features_all_except_vmx[] = { MSR_IA32_UCODE_REV, MSR_IA32_ARCH_CAPABILITIES, MSR_IA32_PERF_CAPABILITIES, + MSR_VIRTUAL_ENUMERATION, }; static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all_except_vmx) + @@ -1621,7 +1623,8 @@ static bool kvm_is_immutable_feature_msr(u32 msr) ARCH_CAP_PSCHANGE_MC_NO | ARCH_CAP_TSX_CTRL_MSR | ARCH_CAP_TAA_NO | \ ARCH_CAP_SBDR_SSDP_NO | ARCH_CAP_FBSDP_NO | ARCH_CAP_PSDP_NO | \ ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO | ARCH_CAP_GDS_NO | \ - ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR | ARCH_CAP_BHI_NO) + ARCH_CAP_RFDS_NO | ARCH_CAP_RFDS_CLEAR | ARCH_CAP_BHI_NO | \ + ARCH_CAP_VIRTUAL_ENUM) static u64 kvm_get_arch_capabilities(void) { @@ -1635,6 +1638,17 @@ static u64 kvm_get_arch_capabilities(void) */ data |= ARCH_CAP_PSCHANGE_MC_NO; + /* + * Virtual enumeration is a paravirt feature. The only usage for now + * is to bridge the gap caused by microarchitecture changes between + * different Intel processors. And its usage is linked to "virtualize + * IA32_SPEC_CTRL" which is a VMX feature. Whether AMD SVM can benefit + * from the same usage and how to implement it is still unclear. Limit + * virtual enumeration to VMX. + */ + if (static_call(kvm_x86_has_emulated_msr)(NULL, MSR_VIRTUAL_ENUMERATION)) + data |= ARCH_CAP_VIRTUAL_ENUM; + /* * If we're doing cache flushes (either "always" or "cond") * we will do one whenever the guest does a vmlaunch/vmresume.