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AFNElJ8H/xhIX2aWlKCZUK6aMmGhnD7KuPwP0tYGsZpDoFfE3+Gqw6MeK8HLWftjf/XH0c78OycZZOQUP+UA5qg=@vger.kernel.org X-Gm-Message-State: AOJu0Ywi4AgCs0EZk4759zUc/LySj+IsduWZg2phQR6JVRi6XLA7HWu7 e1smrR3BVFmvih/adjXrAGlbIrJMVDeVu/XTUkn1UdG+yfbLS/GLYp8YlOH/9mbGtJT7zIoNx2/ z03/MoQ== X-Received: from plzv4.prod.google.com ([2002:a17:902:b7c4:b0:2bd:d2c2:2776]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:38c3:b0:2ba:a7f4:15b0 with SMTP id d9443c01a7336-2beb08a91a1mr193820695ad.19.1779833521237; Tue, 26 May 2026 15:12:01 -0700 (PDT) Date: Tue, 26 May 2026 15:12:00 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: Message-ID: Subject: Re: [PATCH] KVM: VMX: Use _safe MSR accessors in LBR handler From: Sean Christopherson To: xuanqingshi <1356292400@qq.com> Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Tue, May 26, 2026, Sean Christopherson wrote: > On Wed, May 27, 2026, xuanqingshi wrote: > > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > > index 27eb76e6b6a0..94d2cbffcff4 100644 > > --- a/arch/x86/kvm/vmx/pmu_intel.c > > +++ b/arch/x86/kvm/vmx/pmu_intel.c > > @@ -293,6 +293,7 @@ static bool intel_pmu_handle_lbr_msrs_access(struct kvm_vcpu *vcpu, > > { > > struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu); > > u32 index = msr_info->index; > > + int err; > > > > if (!intel_pmu_is_valid_lbr_msr(vcpu, index)) > > return false; > > @@ -309,12 +310,12 @@ static bool intel_pmu_handle_lbr_msrs_access(struct kvm_vcpu *vcpu, > > local_irq_disable(); > > if (lbr_desc->event->state == PERF_EVENT_STATE_ACTIVE) { > > if (read) > > - rdmsrq(index, msr_info->data); > > + err = rdmsrq_safe(index, &msr_info->data); > > else > > - wrmsrq(index, msr_info->data); > > + err = wrmsrq_safe(index, msr_info->data); > > I don't love throwing a value at hardware to see what sticks, but given that KVM > disables interception of these MSRs, it's not like there's a better option. > > No need for a v2, I'll rewrite the changelog when applying. Actually, I'll post a v2, because I think it makes sense to continue using the "unsafe" version for RDMSR. It should be impossible to reach this point with a bad MSR index, i.e. we _want_ the resulting WARN if RDMSR fails.