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[34.168.104.7]) by smtp.gmail.com with ESMTPSA id z25-20020aa79499000000b0056ca3569a66sm9483483pfk.129.2022.11.15.17.56.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Nov 2022 17:56:16 -0800 (PST) Date: Wed, 16 Nov 2022 01:56:12 +0000 From: Sean Christopherson To: "Huang, Kai" Cc: "imbrenda@linux.ibm.com" , "aou@eecs.berkeley.edu" , "mjrosato@linux.ibm.com" , "vkuznets@redhat.com" , "farman@linux.ibm.com" , "chenhuacai@kernel.org" , "paul.walmsley@sifive.com" , "palmer@dabbelt.com" , "maz@kernel.org" , "anup@brainfault.org" , "pbonzini@redhat.com" , "borntraeger@linux.ibm.com" , "aleksandar.qemu.devel@gmail.com" , "frankja@linux.ibm.com" , "oliver.upton@linux.dev" , "kvm@vger.kernel.org" , "Yao, Yuan" , "farosas@linux.ibm.com" , "david@redhat.com" , "james.morse@arm.com" , "mpe@ellerman.id.au" , "alexandru.elisei@arm.com" , "linux-s390@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "tglx@linutronix.de" , "Yamahata, Isaku" , "kvmarm@lists.linux.dev" , "suzuki.poulose@arm.com" , "kvm-riscv@lists.infradead.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mips@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" , "Gao, Chao" , "atishp@atishpatra.org" , "linux-riscv@lists.infradead.org" Subject: Re: [PATCH 33/44] KVM: x86: Do VMX/SVM support checks directly in vendor code Message-ID: References: <20221102231911.3107438-1-seanjc@google.com> <20221102231911.3107438-34-seanjc@google.com> <95c3cce88560024566f3b4b0061ca7e62a8a4286.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <95c3cce88560024566f3b4b0061ca7e62a8a4286.camel@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, Nov 15, 2022, Huang, Kai wrote: > On Wed, 2022-11-02 at 23:19 +0000, Sean Christopherson wrote: > > +static bool __init kvm_is_vmx_supported(void) > > +{ > > + if (!cpu_has_vmx()) { > > + pr_err("CPU doesn't support VMX\n"); > > + return false; > > + } > > + > > + if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) || > > +     !boot_cpu_has(X86_FEATURE_VMX)) { > > + pr_err("VMX not enabled in MSR_IA32_FEAT_CTL\n"); > > + return false; > > + } > > + > > + return true; > > +} > > + > >  static int __init vmx_check_processor_compat(void) > >  { > >   struct vmcs_config vmcs_conf; > >   struct vmx_capability vmx_cap; > >   > > - if (!this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) || > > -     !this_cpu_has(X86_FEATURE_VMX)) { > > - pr_err("VMX is disabled on CPU %d\n", smp_processor_id()); > > + if (!kvm_is_vmx_supported()) > >   return -EIO; > > - } > >   > > Looks there's a functional change here -- the old code checks local cpu's > feature bits but the new code always checks bsp's feature bits. Should have no > problem I think, though. Ouch. The bad check will defeat the purpose of doing compat checks. Nice catch!