[PATCH 4/9] KVM: x86: Avoid double CPUID lookup when updating MWAIT at runtime

From: Sean Christopherson
Date: Fri Nov 10 2023 - 18:55:51 EST


Move the handling of X86_FEATURE_MWAIT during CPUID runtime updates to
utilize the lookup done for other CPUID.0x1 features.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5cf3d697ecb3..6777780be6ae 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -276,6 +276,11 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e

cpuid_entry_change(best, X86_FEATURE_APIC,
vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
+
+ if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT))
+ cpuid_entry_change(best, X86_FEATURE_MWAIT,
+ vcpu->arch.ia32_misc_enable_msr &
+ MSR_IA32_MISC_ENABLE_MWAIT);
}

best = cpuid_entry2_find(entries, nent, 7, 0);
@@ -296,14 +301,6 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e
if (kvm_hlt_in_guest(vcpu->kvm) && best &&
(best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
-
- if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {
- best = cpuid_entry2_find(entries, nent, 0x1, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
- if (best)
- cpuid_entry_change(best, X86_FEATURE_MWAIT,
- vcpu->arch.ia32_misc_enable_msr &
- MSR_IA32_MISC_ENABLE_MWAIT);
- }
}

void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
--
2.42.0.869.gea05f2083d-goog