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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id b7sm29710099wri.83.2021.05.12.00.19.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 May 2021 00:19:41 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: kvm@vger.kernel.org, Paolo Bonzini , linux-kernel@vger.kernel.org, Wanpeng Li , Jim Mattson , Maxim Levitsky Subject: Re: [PATCH 5/7] KVM: nVMX: Reset eVMCS clean fields data from prepare_vmcs02() In-Reply-To: References: <20210511111956.1555830-1-vkuznets@redhat.com> <20210511111956.1555830-6-vkuznets@redhat.com> Date: Wed, 12 May 2021 09:19:40 +0200 Message-ID: <87bl9gwh9v.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > On Tue, May 11, 2021, Vitaly Kuznetsov wrote: >> When nested state migration happens during L1's execution, it >> is incorrect to modify eVMCS as it is L1 who 'owns' it at the moment. >> At lease genuine Hyper-v seems to not be very happy when 'clean fields' >> data changes underneath it. >> >> 'Clean fields' data is used in KVM twice: by copy_enlightened_to_vmcs12() >> and prepare_vmcs02_rare() so we can reset it from prepare_vmcs02() instead. >> >> Signed-off-by: Vitaly Kuznetsov >> --- >> arch/x86/kvm/vmx/nested.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >> index 3257a2291693..1661e2e19560 100644 >> --- a/arch/x86/kvm/vmx/nested.c >> +++ b/arch/x86/kvm/vmx/nested.c >> @@ -2090,9 +2090,6 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu) >> >> if (vmx->nested.hv_evmcs) { >> copy_vmcs12_to_enlightened(vmx); >> - /* All fields are clean */ >> - vmx->nested.hv_evmcs->hv_clean_fields |= >> - HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; >> } else { >> copy_vmcs12_to_shadow(vmx); >> } > > Looks like this makes both paths single lines, i.e. the curly braces can be > dropped. > Yea, I've noticed that but I wasn't exactly sure the benefit of removing one line here overwhelms the pain of needing an extra step while doing code archeology with 'git blame' :-) Will drop on v2. >> @@ -2636,6 +2633,12 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, >> >> kvm_rsp_write(vcpu, vmcs12->guest_rsp); >> kvm_rip_write(vcpu, vmcs12->guest_rip); >> + >> + /* Mark all fields as clean so L1 hypervisor can set what's dirty */ >> + if (hv_evmcs) >> + vmx->nested.hv_evmcs->hv_clean_fields |= >> + HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; >> + >> return 0; >> } >> >> -- >> 2.30.2 >> > -- Vitaly