KVM: x86: use general helpers for some cpuid manipulation

Add guest_cpuid_clear() and use it instead of kvm_find_cpuid_entry().
Also replace some uses of kvm_find_cpuid_entry() with guest_cpuid_has().

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.h

@@ -104,6 +104,15 @@ static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_
 	return *reg & bit(x86_feature);
 }
 
+static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x86_feature)
+{
+	int *reg;
+
+	reg = guest_cpuid_get_register(vcpu, x86_feature);
+	if (reg)
+		*reg &= ~bit(x86_feature);
+}
+
 static inline bool guest_cpuid_is_amd(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *best;

arch/x86/kvm/svm.c

@@ -5075,7 +5075,6 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	struct kvm_cpuid_entry2 *entry;
 
 	/* Update nrips enabled cache */
 	svm->nrips_enabled = !!guest_cpuid_has(&svm->vcpu, X86_FEATURE_NRIPS);
@@ -5083,9 +5082,7 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 	if (!kvm_vcpu_apicv_active(vcpu))
 		return;
 
-	entry = kvm_find_cpuid_entry(vcpu, 1, 0);
+	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
-	if (entry)
-		entry->ecx &= ~bit(X86_FEATURE_X2APIC);
 }
 
 static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)

arch/x86/kvm/vmx.c

@@ -9636,15 +9636,13 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 
 	if (vmx_invpcid_supported()) {
 		/* Exposing INVPCID only when PCID is exposed */
-		struct kvm_cpuid_entry2 *best = kvm_find_cpuid_entry(vcpu, 0x7, 0);
 		bool invpcid_enabled =
-			best && best->ebx & bit(X86_FEATURE_INVPCID) &&
+			guest_cpuid_has(vcpu, X86_FEATURE_INVPCID) &&
 			guest_cpuid_has(vcpu, X86_FEATURE_PCID);
 
 		if (!invpcid_enabled) {
 			secondary_exec_ctl &= ~SECONDARY_EXEC_ENABLE_INVPCID;
-			if (best)
+			guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
-				best->ebx &= ~bit(X86_FEATURE_INVPCID);
 		}
 
 		if (nested) {

arch/x86/kvm/x86.c

@@ -1022,21 +1022,11 @@ bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
 	if (efer & efer_reserved_bits)
 		return false;
 
-	if (efer & EFER_FFXSR) {
+	if (efer & EFER_FFXSR && !guest_cpuid_has(vcpu, X86_FEATURE_FXSR_OPT))
-		struct kvm_cpuid_entry2 *feat;
-
-		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
-		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
 			return false;
-	}
 
-	if (efer & EFER_SVME) {
+	if (efer & EFER_SVME && !guest_cpuid_has(vcpu, X86_FEATURE_SVM))
-		struct kvm_cpuid_entry2 *feat;
-
-		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
-		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
 			return false;
-	}
 
 	return true;
 }