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Wed, 04 Mar 2026 16:25:40 -0800 (PST) Date: Wed, 4 Mar 2026 16:25:39 -0800 In-Reply-To: <20251026201911.505204-4-xin@zytor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251026201911.505204-1-xin@zytor.com> <20251026201911.505204-4-xin@zytor.com> Message-ID: Subject: Re: [PATCH v9 03/22] KVM: VMX: Disable FRED if FRED consistency checks fail From: Sean Christopherson To: "Xin Li (Intel)" Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, pbonzini@redhat.com, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, andrew.cooper3@citrix.com, chao.gao@intel.com, hch@infradead.org, sohil.mehta@intel.com Content-Type: text/plain; charset="us-ascii" On Sun, Oct 26, 2025, Xin Li (Intel) wrote: > diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h > index 6bd67c40ca3b..651507627ef3 100644 > --- a/arch/x86/kvm/vmx/capabilities.h > +++ b/arch/x86/kvm/vmx/capabilities.h > @@ -405,6 +405,16 @@ static inline bool vmx_pebs_supported(void) > return boot_cpu_has(X86_FEATURE_PEBS) && kvm_pmu_cap.pebs_ept; > } > > +static inline bool cpu_has_vmx_fred(void) > +{ > + /* > + * setup_vmcs_config() guarantees FRED VM-entry/exit controls > + * are either all set or none. So, no need to check FRED VM-exit > + * controls. > + */ Eh, omit the comment, there are at least six other control pairs that use this logic. > + return (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_FRED); Unnecessary parentheses. > +} > + > static inline bool cpu_has_notify_vmexit(void) > { > return vmcs_config.cpu_based_2nd_exec_ctrl & > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index be48ba2d70e1..fcfa99160018 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -8020,6 +8020,9 @@ static __init void vmx_set_cpu_caps(void) > kvm_cpu_cap_check_and_set(X86_FEATURE_DTES64); > } > > + if (!cpu_has_vmx_fred()) > + kvm_cpu_cap_clear(X86_FEATURE_FRED); > + > if (!enable_pmu) > kvm_cpu_cap_clear(X86_FEATURE_PDCM); > kvm_caps.supported_perf_cap = vmx_get_perf_capabilities(); > -- > 2.51.0 >