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[35.247.111.240]) by smtp.gmail.com with ESMTPSA id a7sm17231034pfo.105.2021.03.23.09.08.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Mar 2021 09:08:51 -0700 (PDT) Date: Tue, 23 Mar 2021 16:08:47 +0000 From: Sean Christopherson To: Cathy Avery Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, wei.huang2@amd.com Subject: Re: [PATCH] KVM: nSVM: Additions to optimizing L12 to L2 vmcb.save copies Message-ID: References: <20210317162930.28135-1-cavery@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210317162930.28135-1-cavery@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Mar 17, 2021, Cathy Avery wrote: > Extend using the vmcb12 control clean field to determine which > vmcb12.save registers were marked dirty in order to minimize > register copies by including the CR bit. > > This patch also fixes the init of last_vmcb12_gpa by using an invalid > physical address instead of 0. > > Tested: > kvm-unit-tests > kvm selftests > Fedora L1 L2 > > Signed-off-by: Cathy Avery > --- > arch/x86/kvm/svm/nested.c | 9 ++++++--- > arch/x86/kvm/svm/svm.c | 2 +- > 2 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > index 8523f60adb92..6f9a40e002bc 100644 > --- a/arch/x86/kvm/svm/nested.c > +++ b/arch/x86/kvm/svm/nested.c > @@ -449,9 +449,12 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 > } > > kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED); > - svm_set_efer(&svm->vcpu, vmcb12->save.efer); > - svm_set_cr0(&svm->vcpu, vmcb12->save.cr0); > - svm_set_cr4(&svm->vcpu, vmcb12->save.cr4); > + > + if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_CR))) { > + svm_set_efer(&svm->vcpu, vmcb12->save.efer); > + svm_set_cr0(&svm->vcpu, vmcb12->save.cr0); > + svm_set_cr4(&svm->vcpu, vmcb12->save.cr4); This doesn't seem correct. Regardless of when vmcb12 was last touched, KVM still needs to set L2's state in vcpu->arch and set the correct MMU context. > + } > > svm->vcpu.arch.cr2 = vmcb12->save.cr2; > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 271196400495..41f5cd1009ca 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1234,7 +1234,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu) > svm->asid = 0; > > svm->nested.vmcb12_gpa = 0; > - svm->nested.last_vmcb12_gpa = 0; > + svm->nested.last_vmcb12_gpa = -1; INVALID_PAGE would be even better. > vcpu->arch.hflags = 0; > > if (!kvm_pause_in_guest(vcpu->kvm)) { > -- > 2.26.2 >