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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id k1sm1937588wrp.23.2020.11.12.00.32.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2020 00:32:40 -0800 (PST) To: Babu Moger Cc: junaids@google.com, wanpengli@tencent.com, kvm@vger.kernel.org, joro@8bytes.org, x86@kernel.org, linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, tglx@linutronix.de, vkuznets@redhat.com, jmattson@google.com References: <160514082171.31583.9995411273370528911.stgit@bmoger-ubuntu> <160514090654.31583.12433653224184517852.stgit@bmoger-ubuntu> From: Paolo Bonzini Subject: Re: [PATCH 2/2] KVM:SVM: Mask SEV encryption bit from CR3 reserved bits Message-ID: <09c5a083-a841-7d0e-f315-1d480e929957@redhat.com> Date: Thu, 12 Nov 2020 09:32:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <160514090654.31583.12433653224184517852.stgit@bmoger-ubuntu> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/11/20 01:28, Babu Moger wrote: > Add support to the mask_cr3_rsvd_bits() callback to mask the > encryption bit from the CR3 value when SEV is enabled. > > Additionally, cache the encryption mask for quick access during > the check. > > Fixes: a780a3ea628268b2 ("KVM: X86: Fix reserved bits check for MOV to CR3") > Signed-off-by: Babu Moger > --- > arch/x86/kvm/svm/svm.c | 11 ++++++++++- > arch/x86/kvm/svm/svm.h | 3 +++ > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index a491a47d7f5c..c2b1e52810c6 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -3741,6 +3741,7 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > + struct kvm_cpuid_entry2 *best; > > vcpu->arch.xsaves_enabled = guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) && > boot_cpu_has(X86_FEATURE_XSAVE) && > @@ -3771,6 +3772,12 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) > if (nested && guest_cpuid_has(vcpu, X86_FEATURE_SVM)) > kvm_request_apicv_update(vcpu->kvm, false, > APICV_INHIBIT_REASON_NESTED); > + > + best = kvm_find_cpuid_entry(vcpu, 0x8000001F, 0); > + if (best) > + svm->sev_enc_mask = ~(1UL << (best->ebx & 0x3f)); > + else > + svm->sev_enc_mask = ~0UL; > } > > static bool svm_has_wbinvd_exit(void) > @@ -4072,7 +4079,9 @@ static void enable_smi_window(struct kvm_vcpu *vcpu) > > static unsigned long svm_mask_cr3_rsvd_bits(struct kvm_vcpu *vcpu, unsigned long cr3) > { > - return cr3; > + struct vcpu_svm *svm = to_svm(vcpu); > + > + return sev_guest(vcpu->kvm) ? (cr3 & svm->sev_enc_mask) : cr3; > } > > static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int insn_len) > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index 1d853fe4c778..57a36645a0e4 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -152,6 +152,9 @@ struct vcpu_svm { > u64 *avic_physical_id_cache; > bool avic_is_running; > > + /* SEV Memory encryption mask */ > + unsigned long sev_enc_mask; > + > /* > * Per-vcpu list of struct amd_svm_iommu_ir: > * This is used mainly to store interrupt remapping information used > Instead of adding a new callback, you can add a field to struct kvm_vcpu_arch: if (is_long_mode(vcpu) && - (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63))) + (cr3 & vcpu->arch.cr3_lm_rsvd_bits)) Set it in kvm_vcpu_after_set_cpuid, and clear the memory encryption bit in kvm_x86_ops.vcpu_after_set_cpuid. Paolo