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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id o6sm2602785edw.24.2021.03.03.01.36.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Mar 2021 01:36:41 -0800 (PST) From: Vitaly Kuznetsov To: Yang Weijiang Cc: pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: nVMX: Add CET entry/exit load bits to evmcs unsupported list In-Reply-To: <20210303060435.8158-1-weijiang.yang@intel.com> References: <20210303060435.8158-1-weijiang.yang@intel.com> Date: Wed, 03 Mar 2021 10:36:40 +0100 Message-ID: <87h7lsefyv.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Yang Weijiang writes: > CET in nested guest over Hyper-V is not supported for now. Relevant > enabling patches will be posted as a separate patch series. > > Suggested-by: Paolo Bonzini > Signed-off-by: Yang Weijiang > --- > arch/x86/kvm/vmx/evmcs.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h > index bd41d9462355..25588694eb04 100644 > --- a/arch/x86/kvm/vmx/evmcs.h > +++ b/arch/x86/kvm/vmx/evmcs.h > @@ -59,8 +59,10 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs); > SECONDARY_EXEC_SHADOW_VMCS | \ > SECONDARY_EXEC_TSC_SCALING | \ > SECONDARY_EXEC_PAUSE_LOOP_EXITING) > -#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) > -#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) > +#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | \ > + VM_EXIT_LOAD_CET_STATE) > +#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL | \ > + VM_ENTRY_LOAD_CET_STATE) > #define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING) > > #if IS_ENABLED(CONFIG_HYPERV) This should be enough when we run KVM on Hyper-V using eVMCS, however, it may not suffice when we run Hyper-V on KVM using eVMCS: there's still no corresponding eVMCS fields so CET can't be used. In case Hyper-V is smart enough it won't use the feature, however, it was proven to be 'not very smart' in the past, see nested_evmcs_filter_control_msr(). I'm wondering if we should also do diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c index 41f24661af04..9f81db51fd8b 100644 --- a/arch/x86/kvm/vmx/evmcs.c +++ b/arch/x86/kvm/vmx/evmcs.c @@ -351,11 +351,11 @@ void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata) switch (msr_index) { case MSR_IA32_VMX_EXIT_CTLS: case MSR_IA32_VMX_TRUE_EXIT_CTLS: - ctl_high &= ~VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL; + ctl_high &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL; break; case MSR_IA32_VMX_ENTRY_CTLS: case MSR_IA32_VMX_TRUE_ENTRY_CTLS: - ctl_high &= ~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL; + ctl_high &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL; break; case MSR_IA32_VMX_PROCBASED_CTLS2: ctl_high &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES; to be on the safe side. -- Vitaly