From 73392706d0e0f3aff299321de41d73abe3f53d9d Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 4 Sep 2026 10:06:42 -0700 Subject: [PATCH] KVM: SVM: Sync guest's PERF_CNTR_GLOBAL_CTL from h/w only on successful VMRUN Don't (re)read PERF_CNTR_GLOBAL_CTL from hardware on a failed VMRUN, as the purpose of the read is to synchronize KVM's cache with any writes done by the guest, and the guest can't possibly have modified the MSR if it never got a chance to run. Signed-off-by: Sean Christopherson Message-ID: <20260904170642.3291466-5-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/svm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 830ace75e986..f4f488328ea4 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4632,6 +4632,10 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) svm->vmcb->control.erap_ctl &= ~ERAP_CONTROL_CLEAR_RAP; vmcb_mark_all_clean(svm->vmcb); + + if (!msr_write_intercepted(svm, MSR_AMD64_PERF_CNTR_GLOBAL_CTL)) + rdmsrq(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, + vcpu_to_pmu(vcpu)->global_ctrl); } /* if exit due to PF check for async PF */ @@ -4641,9 +4645,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) kvm_clear_available_registers(vcpu, SVM_REGS_LAZY_LOAD_SET); - if (!msr_write_intercepted(svm, MSR_AMD64_PERF_CNTR_GLOBAL_CTL)) - rdmsrq(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, vcpu_to_pmu(vcpu)->global_ctrl); - trace_kvm_exit(vcpu, KVM_ISA_SVM); svm_complete_interrupts(vcpu);