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| author |   Babu Moger <babu.moger@amd.com> | 2022-04-19 15:54:44 -0500 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2022-04-29 12:49:15 -0400 |
| commit | 296d5a17e793956f7b914336422043c939263409 (patch) | |
| tree | e6dae9614be53367fac2eec0fe49eaaa5ceb13da /arch/x86/kvm/svm/sev.c | |
| parent | x86/cpufeatures: Add virtual TSC_AUX feature bit (diff) | |
| download | wireguard-linux-296d5a17e793956f7b914336422043c939263409.tar.xz wireguard-linux-296d5a17e793956f7b914336422043c939263409.zip | |
KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts
The TSC_AUX virtualization feature allows AMD SEV-ES guests to securely use
TSC_AUX (auxiliary time stamp counter data) in the RDTSCP and RDPID
instructions. The TSC_AUX value is set using the WRMSR instruction to the
TSC_AUX MSR (0xC0000103). It is read by the RDMSR, RDTSCP and RDPID
instructions. If the read/write of the TSC_AUX MSR is intercepted, then
RDTSCP and RDPID must also be intercepted when TSC_AUX virtualization
is present. However, the RDPID instruction can't be intercepted. This means
that when TSC_AUX virtualization is present, RDTSCP and TSC_AUX MSR
read/write must not be intercepted for SEV-ES (or SEV-SNP) guests.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Message-Id: <165040164424.1399644.13833277687385156344.stgit@bmoger-ubuntu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/svm/sev.c')
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 9ce162119b23..b67ce873d5d2 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2926,6 +2926,14 @@ void sev_es_init_vmcb(struct vcpu_svm *svm) set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTBRANCHTOIP, 1, 1); set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTFROMIP, 1, 1); set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTTOIP, 1, 1); + + if (boot_cpu_has(X86_FEATURE_V_TSC_AUX) && + (guest_cpuid_has(&svm->vcpu, X86_FEATURE_RDTSCP) || + guest_cpuid_has(&svm->vcpu, X86_FEATURE_RDPID))) { + set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, 1, 1); + if (guest_cpuid_has(&svm->vcpu, X86_FEATURE_RDTSCP)) + svm_clr_intercept(svm, INTERCEPT_RDTSCP); + } } void sev_es_vcpu_reset(struct vcpu_svm *svm) |