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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id l5sm4806923wml.3.2020.03.03.08.12.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Mar 2020 08:12:04 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li Subject: Re: [PATCH v2 64/66] KVM: nSVM: Expose SVM features to L1 iff nested is enabled In-Reply-To: <20200302235709.27467-65-sean.j.christopherson@intel.com> References: <20200302235709.27467-1-sean.j.christopherson@intel.com> <20200302235709.27467-65-sean.j.christopherson@intel.com> Date: Tue, 03 Mar 2020 17:12:03 +0100 Message-ID: <878skhfmek.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > Set SVM feature bits in KVM capabilities if and only if nested=true, KVM > shouldn't advertise features that realistically can't be used. Use > kvm_cpu_cap_has(X86_FEATURE_SVM) to indirectly query "nested" in > svm_set_supported_cpuid() in anticipation of moving CPUID 0x8000000A > adjustments into common x86 code. > > Suggested-by: Paolo Bonzini > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/svm.c | 22 +++++++++++++--------- > 1 file changed, 13 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index f32fc3c03667..8e39dcd3160d 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -1373,21 +1373,21 @@ static __init void svm_set_cpu_caps(void) > if (avic) > kvm_cpu_cap_clear(X86_FEATURE_X2APIC); > > - /* CPUID 0x80000001 */ > - if (nested) > + /* CPUID 0x80000001 and 0x8000000A (SVM features) */ > + if (nested) { > kvm_cpu_cap_set(X86_FEATURE_SVM); > > + if (boot_cpu_has(X86_FEATURE_NRIPS)) > + kvm_cpu_cap_set(X86_FEATURE_NRIPS); > + > + if (npt_enabled) > + kvm_cpu_cap_set(X86_FEATURE_NPT); > + } > + > /* CPUID 0x80000008 */ > if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || > boot_cpu_has(X86_FEATURE_AMD_SSBD)) > kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD); > - > - /* CPUID 0x8000000A */ > - /* Support next_rip if host supports it */ > - kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS); > - > - if (npt_enabled) > - kvm_cpu_cap_set(X86_FEATURE_NPT); > } > > static __init int svm_hardware_setup(void) > @@ -6051,6 +6051,10 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) > { > switch (entry->function) { > case 0x8000000A: > + if (!kvm_cpu_cap_has(X86_FEATURE_SVM)) { > + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + break; > + } > entry->eax = 1; /* SVM revision 1 */ > entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper > ASID emulation to nested SVM */ Reviewed-by: Vitaly Kuznetsov -- Vitaly