[PATCH v2 2/3] KVM: SVM: Fix TSC_AUX virtualization intercept update logic

From: Tom Lendacky
Date: Fri Sep 15 2023 - 16:58:32 EST


With the TSC_AUX virtualization support now in the vcpu_set_after_cpuid()
path, the intercepts must be either cleared or set based on the guest
CPUID input. Currently the support only clears the intercepts.

Also, vcpu_set_after_cpuid() calls svm_recalc_instruction_intercepts() as
part of the processing, so the setting or clearing of the RDTSCP intercept
can be dropped from the TSC_AUX virtualization support.

Update the support to always set or clear the TSC_AUX MSR intercept based
on the virtualization requirements.

Fixes: 296d5a17e793 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts")
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
arch/x86/kvm/svm/sev.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4ac01f338903..4900c078045a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2966,12 +2966,11 @@ static void sev_es_vcpu_after_set_cpuid(struct vcpu_svm *svm)
{
struct kvm_vcpu *vcpu = &svm->vcpu;

- if (boot_cpu_has(X86_FEATURE_V_TSC_AUX) &&
- (guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
- guest_cpuid_has(vcpu, X86_FEATURE_RDPID))) {
- set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, 1, 1);
- if (guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
- svm_clr_intercept(svm, INTERCEPT_RDTSCP);
+ if (boot_cpu_has(X86_FEATURE_V_TSC_AUX)) {
+ bool v_tsc_aux = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
+ guest_cpuid_has(vcpu, X86_FEATURE_RDPID);
+
+ set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, v_tsc_aux, v_tsc_aux);
}
}

--
2.41.0