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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id g25sm9302750wmh.3.2020.02.05.06.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2020 06:53:45 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini Subject: Re: [PATCH 06/26] KVM: x86: Move MSR_IA32_BNDCFGS existence checks into vendor code In-Reply-To: <20200129234640.8147-7-sean.j.christopherson@intel.com> References: <20200129234640.8147-1-sean.j.christopherson@intel.com> <20200129234640.8147-7-sean.j.christopherson@intel.com> Date: Wed, 05 Feb 2020 15:53:45 +0100 Message-ID: <878slhkruu.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > Move the MSR_IA32_BNDCFGS existence check into vendor code by way of > ->has_virtualized_msr(). AMD does not support MPX, and given that Intel > is in the process of removing MPX, it's extremely unlikely AMD will ever > support MPX. > > Note, invoking ->has_virtualized_msr() requires an extra retpoline, but > kvm_init_msr_list() is not a hot path. As alluded to above, the > motivation is to quarantine MPX as much as possible. > > No functional change intended. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/svm.c | 2 ++ > arch/x86/kvm/vmx/vmx.c | 2 ++ > arch/x86/kvm/x86.c | 4 ---- > 3 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 4c8427f57b71..504118c49f46 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -5990,6 +5990,8 @@ static bool svm_has_virtualized_msr(u32 index) > switch (index) { > case MSR_TSC_AUX: > return boot_cpu_has(X86_FEATURE_RDTSCP); > + case MSR_IA32_BNDCFGS: > + return false; > default: > break; > } > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 9588914e941e..dbeef64f7409 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -6279,6 +6279,8 @@ static bool vmx_has_virtualized_msr(u32 index) > switch (index) { > case MSR_TSC_AUX: > return cpu_has_vmx_rdtscp(); > + case MSR_IA32_BNDCFGS: > + return kvm_mpx_supported(); > default: > break; > } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index a8619c52ea86..70cbb9164088 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5237,10 +5237,6 @@ static void kvm_init_msr_list(void) > * to the guests in some cases. > */ > switch (msr_index) { > - case MSR_IA32_BNDCFGS: > - if (!kvm_mpx_supported()) > - continue; > - break; > case MSR_IA32_RTIT_CTL: > case MSR_IA32_RTIT_STATUS: > if (!kvm_x86_ops->pt_supported()) Reviewed-by: Vitaly Kuznetsov -- Vitaly