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Tsirkin" , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v7 3/7] KVM: VMX: Pass through CET related MSRs to Guest Message-ID: <20191017200411.GL20903@linux.intel.com> References: <20190927021927.23057-1-weijiang.yang@intel.com> <20190927021927.23057-4-weijiang.yang@intel.com> <20191009061509.GB27851@local-michael-cet-test> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191009061509.GB27851@local-michael-cet-test> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 09, 2019 at 02:15:09PM +0800, Yang Weijiang wrote: > On Wed, Oct 02, 2019 at 11:18:32AM -0700, Jim Mattson wrote: > > > + kvm_xss = kvm_supported_xss(); > > > + cet_en = guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > > > + guest_cpuid_has(vcpu, X86_FEATURE_IBT); > > > + /* > > > + * U_CET is a must for USER CET, per CET spec., U_CET and PL3_SPP are > > > + * a bundle for USER CET xsaves. > > > + */ > > > + if (cet_en && (kvm_xss & XFEATURE_MASK_CET_USER)) { > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_U_CET, MSR_TYPE_RW); > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL3_SSP, MSR_TYPE_RW); > > > + } > > > > Since this is called from vmx_cpuid_update, what happens if cet_en was > > previously true and now it's false? > > > Yes, it's likely, but guest CPUID usually is fixed before > guest is launched, do you have any suggestion? Re-enable interception. kvm_x86_ops->cpuid_update() is only called in the ioctl flow, i.e. it's not performance critical. > > > + /* > > > + * S_CET is a must for KERNEL CET, PL0_SSP ... PL2_SSP are a bundle > > > + * for CET KERNEL xsaves. > > > + */ > > > + if (cet_en && (kvm_xss & XFEATURE_MASK_CET_KERNEL)) { > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_S_CET, MSR_TYPE_RW); > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL0_SSP, MSR_TYPE_RW); > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL1_SSP, MSR_TYPE_RW); > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL2_SSP, MSR_TYPE_RW); > > > + > > > + /* SSP_TAB only available for KERNEL SHSTK.*/ > > > + if (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK)) > > > + vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_INT_SSP_TAB, > > > + MSR_TYPE_RW); > > > + } > > > +} > > > + > > > static void vmx_cpuid_update(struct kvm_vcpu *vcpu) > > > { > > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > > @@ -7025,6 +7062,8 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu) > > > if (boot_cpu_has(X86_FEATURE_INTEL_PT) && > > > guest_cpuid_has(vcpu, X86_FEATURE_INTEL_PT)) > > > update_intel_pt_cfg(vcpu); > > > + > > > + vmx_intercept_cet_msrs(vcpu); > > > } > > > > > > static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) > > > -- > > > 2.17.2 > > >