Track "TSC scaling exposed to L1" via a governed feature flag instead of
using a dedicated bit/flag in vcpu_svm.
Note, this fixes a benign bug where KVM would mark TSC scaling as exposed
to L1 even if overall nested SVM supported is disabled, i.e. KVM would let
L1 write MSR_AMD64_TSC_RATIO even when KVM didn't advertise TSCRATEMSR
support to userspace.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/governed_features.h | 1 +
arch/x86/kvm/svm/nested.c | 2 +-
arch/x86/kvm/svm/svm.c | 10 ++++++----
arch/x86/kvm/svm/svm.h | 1 -
4 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index 722b66af412c..32c0469cf952 100644
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -9,6 +9,7 @@ KVM_GOVERNED_X86_FEATURE(GBPAGES)
KVM_GOVERNED_X86_FEATURE(XSAVES)
KVM_GOVERNED_X86_FEATURE(VMX)
KVM_GOVERNED_X86_FEATURE(NRIPS)
+KVM_GOVERNED_X86_FEATURE(TSCRATEMSR)
#undef KVM_GOVERNED_X86_FEATURE
#undef KVM_GOVERNED_FEATURE
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 9092f3f8dccf..da65948064dc 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -695,7 +695,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
vmcb02->control.tsc_offset = vcpu->arch.tsc_offset;
- if (svm->tsc_scaling_enabled &&
+ if (guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR) &&
svm->tsc_ratio_msr != kvm_caps.default_tsc_scaling_ratio)
nested_svm_update_tsc_ratio_msr(vcpu);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c8b97cb3138c..15c79457d8c5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2809,7 +2809,8 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
switch (msr_info->index) {
case MSR_AMD64_TSC_RATIO:
- if (!msr_info->host_initiated && !svm->tsc_scaling_enabled)
+ if (!msr_info->host_initiated &&
+ !guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR))
return 1;
msr_info->data = svm->tsc_ratio_msr;
break;
@@ -2959,7 +2960,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
switch (ecx) {
case MSR_AMD64_TSC_RATIO:
- if (!svm->tsc_scaling_enabled) {
+ if (!guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR)) {
if (!msr->host_initiated)
return 1;
@@ -2981,7 +2982,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
svm->tsc_ratio_msr = data;
- if (svm->tsc_scaling_enabled && is_guest_mode(vcpu))
+ if (guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR) &&
+ is_guest_mode(vcpu))
nested_svm_update_tsc_ratio_msr(vcpu);
break;
@@ -4289,8 +4291,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
kvm_governed_feature_set(vcpu, X86_FEATURE_XSAVES);
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_NRIPS);
+ kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_TSCRATEMSR);
- svm->tsc_scaling_enabled = tsc_scaling && guest_cpuid_has(vcpu, X86_FEATURE_TSCRATEMSR);
svm->lbrv_enabled = lbrv && guest_cpuid_has(vcpu, X86_FEATURE_LBRV);
svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index e147f2046ffa..3696f10e2887 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -259,7 +259,6 @@ struct vcpu_svm {
bool soft_int_injected;
/* optional nested SVM features that are enabled for this guest */
- bool tsc_scaling_enabled : 1;
bool v_vmload_vmsave_enabled : 1;
bool lbrv_enabled : 1;
bool pause_filter_enabled : 1;
--
2.41.0.694.ge786442a9b-goog
