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Thu, 03 Apr 2025 13:04:27 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEo9LOR/QTdiYbvtlfOeC04oRbI9fAMuBy7hvGsx2K2DNOTFI5IS0fHaCtTn4DM15/wrGnywQ== X-Received: by 2002:a05:622a:448:b0:476:8288:955f with SMTP id d75a77b69052e-4792490fb2emr11018581cf.8.1743710666704; Thu, 03 Apr 2025 13:04:26 -0700 (PDT) Received: from starship ([2607:fea8:fc01:8d8d:6adb:55ff:feaa:b156]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4791b0719b8sm11733041cf.24.2025.04.03.13.04.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 13:04:26 -0700 (PDT) Message-ID: <26cedde1e10a210556aabf7510b1d08ee73dca0a.camel@redhat.com> Subject: Re: [RFC PATCH 07/24] KVM: SEV: Track ASID->vCPU on vCPU load From: Maxim Levitsky To: Yosry Ahmed , Sean Christopherson Cc: Paolo Bonzini , Jim Mattson , Vitaly Kuznetsov , Rik van Riel , Tom Lendacky , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 03 Apr 2025 16:04:25 -0400 In-Reply-To: <20250326193619.3714986-8-yosry.ahmed@linux.dev> References: <20250326193619.3714986-1-yosry.ahmed@linux.dev> <20250326193619.3714986-8-yosry.ahmed@linux.dev> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit On Wed, 2025-03-26 at 19:36 +0000, Yosry Ahmed wrote: > Check for changes in the ASID to vCPU mapping on vCPU load instead of > doing it on vCPU run. This should be sufficient and more efficient, and > is needed to allow generalizing the tracking and making it more > expensive. > > Signed-off-by: Yosry Ahmed > --- > arch/x86/kvm/svm/sev.c | 13 ++++--------- > arch/x86/kvm/svm/svm.c | 13 +++++++++++++ > arch/x86/kvm/svm/svm.h | 1 + > 3 files changed, 18 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index ddb4d5b211ed7..3ef0dfdbb34d2 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -224,7 +224,7 @@ static int sev_asid_new(struct kvm_sev_info *sev) > return ret; > } > > -static unsigned int sev_get_asid(struct kvm *kvm) > +unsigned int sev_get_asid(struct kvm *kvm) > { > return to_kvm_sev_info(kvm)->asid; > } > @@ -3453,7 +3453,6 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm) > > int pre_sev_run(struct vcpu_svm *svm, int cpu) > { > - struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, cpu); > struct kvm *kvm = svm->vcpu.kvm; > unsigned int asid = sev_get_asid(kvm); > > @@ -3469,16 +3468,12 @@ int pre_sev_run(struct vcpu_svm *svm, int cpu) > svm->asid = asid; > > /* > - * Flush guest TLB: > - * > - * 1) when different vCPU for the same ASID is to be run on the same host CPU. > - * 2) or this VMCB was executed on different host CPU in previous VMRUNs. > + * Flush guest TLB if the VMCB was executed on a differet host CPU in > + * previous VMRUNs. > */ > - if (sd->sev_vcpus[asid] == &svm->vcpu && > - svm->vcpu.arch.last_vmentry_cpu == cpu) > + if (svm->vcpu.arch.last_vmentry_cpu == cpu) > return 0; > > - sd->sev_vcpus[asid] = &svm->vcpu; > vmcb_set_flush_asid(svm->vmcb); > vmcb_mark_dirty(svm->vmcb, VMCB_ASID); > return 0; > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 1156ca97fd798..e6e380411fbec 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1554,6 +1554,7 @@ static void svm_prepare_host_switch(struct kvm_vcpu *vcpu) > > static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > { > + unsigned int asid; > struct vcpu_svm *svm = to_svm(vcpu); > struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, cpu); > > @@ -1568,6 +1569,18 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > } > if (kvm_vcpu_apicv_active(vcpu)) > avic_vcpu_load(vcpu, cpu); > + > + if (sev_guest(vcpu->kvm)) { > + /* > + * Flush the TLB when a different vCPU using the same ASID is > + * run on the same CPU. > + */ > + asid = sev_get_asid(vcpu->kvm); > + if (sd->sev_vcpus[asid] != vcpu) { > + sd->sev_vcpus[asid] = vcpu; > + kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); > + } > + } > } > > static void svm_vcpu_put(struct kvm_vcpu *vcpu) > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index 4ea6c61c3b048..ca38a233fa24c 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -768,6 +768,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm); > void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector); > void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa); > void sev_es_unmap_ghcb(struct vcpu_svm *svm); > +unsigned int sev_get_asid(struct kvm *kvm); > > #ifdef CONFIG_KVM_AMD_SEV > int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp); Makes sense, but I might have missed something. Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky