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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id 21sm4679202wme.6.2021.03.30.10.10.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Mar 2021 10:10:31 -0700 (PDT) Subject: Re: [PATCH] KVM: x86/vPMU: Forbid reading from MSR_F15H_PERF MSRs when guest doesn't have X86_FEATURE_PERFCTR_CORE To: Vitaly Kuznetsov , kvm@vger.kernel.org Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Wei Huang , Joerg Roedel , Haiwei Li , linux-kernel@vger.kernel.org References: <20210329124804.170173-1-vkuznets@redhat.com> From: Paolo Bonzini Message-ID: <3a741047-48a7-ee72-27ec-f83b0b7669f6@redhat.com> Date: Tue, 30 Mar 2021 19:10:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210329124804.170173-1-vkuznets@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/03/21 14:48, Vitaly Kuznetsov wrote: > MSR_F15H_PERF_CTL0-5, MSR_F15H_PERF_CTR0-5 MSRs have a CPUID bit assigned > to them (X86_FEATURE_PERFCTR_CORE) and when it wasn't exposed to the guest > the correct behavior is to inject #GP an not just return zero. > > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/kvm/x86.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fe806e894212..125453155ede 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3381,6 +3381,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > msr_info->data = 0; > break; > case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5: > + if (kvm_pmu_is_valid_msr(vcpu, msr_info->index)) > + return kvm_pmu_get_msr(vcpu, msr_info); > + if (!msr_info->host_initiated) > + return 1; > + msr_info->data = 0; > + break; > case MSR_K7_EVNTSEL0 ... MSR_K7_EVNTSEL3: > case MSR_K7_PERFCTR0 ... MSR_K7_PERFCTR3: > case MSR_P6_PERFCTR0 ... MSR_P6_PERFCTR1: > Queued to kvm/next, thanks (the write side goes to kvm/master instead). Paolo