[v11,13/16] KVM: x86: Use KVM-governed feature framework to track "LAM enabled"

Commit Message

Binbin Wu Sept. 13, 2023, 12:42 p.m. UTC

Use the governed feature framework to track if Linear Address Masking (LAM)
is "enabled", i.e. if LAM can be used by the guest.

Using the framework to avoid the relative expensive call guest_cpuid_has()
during cr3 and vmexit handling paths for LAM.

No functional change intended.

Signed-off-by: Binbin Wu <[e-mail]>
Tested-by: Xuelian Guo <[e-mail]>
---
 arch/x86/kvm/cpuid.h             | 3 +--
 arch/x86/kvm/governed_features.h | 1 +
 arch/x86/kvm/mmu.h               | 3 +--
 arch/x86/kvm/vmx/vmx.c           | 1 +
 4 files changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 3c579ce2f60f..93c63ba29337 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -275,8 +275,7 @@  static __always_inline bool guest_can_use(struct kvm_vcpu *vcpu,
 
 static inline bool kvm_vcpu_is_legal_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 {
-	if (kvm_cpu_cap_has(X86_FEATURE_LAM) &&
-	    guest_cpuid_has(vcpu, X86_FEATURE_LAM))
+	if (guest_can_use(vcpu, X86_FEATURE_LAM))
 		cr3 &= ~(X86_CR3_LAM_U48 | X86_CR3_LAM_U57);
 
 	return kvm_vcpu_is_legal_gpa(vcpu, cr3);
diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index 423a73395c10..ad463b1ed4e4 100644
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -16,6 +16,7 @@  KVM_GOVERNED_X86_FEATURE(PAUSEFILTER)
 KVM_GOVERNED_X86_FEATURE(PFTHRESHOLD)
 KVM_GOVERNED_X86_FEATURE(VGIF)
 KVM_GOVERNED_X86_FEATURE(VNMI)
+KVM_GOVERNED_X86_FEATURE(LAM)
 
 #undef KVM_GOVERNED_X86_FEATURE
 #undef KVM_GOVERNED_FEATURE
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index e700f1f854ae..f04cc5ade1cd 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -148,8 +148,7 @@  static inline unsigned long kvm_get_active_pcid(struct kvm_vcpu *vcpu)
 
 static inline unsigned long kvm_get_active_cr3_lam_bits(struct kvm_vcpu *vcpu)
 {
-	if (!kvm_cpu_cap_has(X86_FEATURE_LAM) ||
-	    !guest_cpuid_has(vcpu, X86_FEATURE_LAM))
+	if (!guest_can_use(vcpu, X86_FEATURE_LAM))
 		return 0;
 
 	return kvm_read_cr3(vcpu) & (X86_CR3_LAM_U48 | X86_CR3_LAM_U57);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 23eac6bb4fac..3bdeebee71cc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7767,6 +7767,7 @@  static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 		kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_XSAVES);
 
 	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_VMX);
+	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_LAM);
 
 	vmx_setup_uret_msrs(vmx);