linux-kernel - [PATCH 3/3] KVM: VMX: Drop manual checks on X86_FEATURE_MSR_IA32_FEAT

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Message-ID: <20221203003745.1475584-4-seanjc@google.com>
Date:   Sat,  3 Dec 2022 00:37:45 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: [PATCH 3/3] KVM: VMX: Drop manual checks on X86_FEATURE_MSR_IA32_FEAT_CTL

Drop manual checks on X86_FEATURE_MSR_IA32_FEAT_CTL and instead rely
solely on the X86_FEATURE_VMX check to detect VMX support now that VMX is
disabled via apply_cpuid_deps() if X86_FEATURE_MSR_IA32_FEAT_CTL isn't
supported.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kernel/cpu/bugs.c | 3 +--
 arch/x86/kvm/vmx/vmx.c     | 6 ++----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 9e84b685328f..3071e2a97f0d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2222,8 +2222,7 @@ static ssize_t l1tf_show_state(char *buf)
 
 static ssize_t itlb_multihit_show_state(char *buf)
 {
-	if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
-	    !boot_cpu_has(X86_FEATURE_VMX))
+	if (!boot_cpu_has(X86_FEATURE_VMX))
 		return sysfs_emit(buf, "KVM: Mitigation: VMX unsupported\n");
 	else if (!(cr4_read_shadow() & X86_CR4_VMXE))
 		return sysfs_emit(buf, "KVM: Mitigation: VMX disabled\n");
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9dba04b6b019..de3fe3932ee8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2423,8 +2423,7 @@ static __init int cpu_has_kvm_support(void)
 
 static __init int vmx_disabled_by_bios(void)
 {
-	return !boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
-	       !boot_cpu_has(X86_FEATURE_VMX);
+	return !boot_cpu_has(X86_FEATURE_VMX);
 }
 
 static int kvm_cpu_vmxon(u64 vmxon_pointer)
@@ -7413,8 +7412,7 @@ 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)) {
+	if (!this_cpu_has(X86_FEATURE_VMX)) {
 		pr_err("kvm: VMX is disabled on CPU %d\n", smp_processor_id());
 		return -EIO;
 	}
-- 
2.39.0.rc0.267.gcb52ba06e7-goog