linux-kernel - [PATCH RFC 2/2] KVM: x86: use general helpers for some cpuid manipulation

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Message-Id: <20170802204147.3586-3-rkrcmar@redhat.com>
Date:   Wed,  2 Aug 2017 22:41:47 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        David Hildenbrand <david@...hat.com>
Subject: [PATCH RFC 2/2] 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@...hat.com>
---
 arch/x86/kvm/cpuid.h |  9 +++++++++
 arch/x86/kvm/svm.c   |  5 +----
 arch/x86/kvm/vmx.c   |  9 +++------
 arch/x86/kvm/x86.c   | 14 ++------------
 4 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 3b17d915b608..650b5c80c5a0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -104,6 +104,15 @@ static inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_feature)
 	return *reg & bit(x86_feature);
 }
 
+static 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;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index fcdc1412792e..5ceb99ff145b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5065,7 +5065,6 @@ 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);
@@ -5073,9 +5072,7 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 	if (!kvm_vcpu_apicv_active(vcpu))
 		return;
 
-	entry = kvm_find_cpuid_entry(vcpu, 1, 0);
-	if (entry)
-		entry->ecx &= ~bit(X86_FEATURE_X2APIC);
+	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
 }
 
 static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8367f901d681..e34373838b31 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9376,7 +9376,6 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
 
 static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpuid_entry2 *best;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u32 secondary_exec_ctl = vmx_secondary_exec_control(vmx);
 
@@ -9396,14 +9395,12 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 	}
 
 	/* Exposing INVPCID only when PCID is exposed */
-	best = kvm_find_cpuid_entry(vcpu, 0x7, 0);
 	if (vmx_invpcid_supported() &&
-	    (!best || !(best->ebx & bit(X86_FEATURE_INVPCID)) ||
-	    !guest_cpuid_has(vcpu, X86_FEATURE_PCID))) {
+	    (!guest_cpuid_has(vcpu, X86_FEATURE_INVPCID) ||
+	     !guest_cpuid_has(vcpu, X86_FEATURE_PCID))) {
 		secondary_exec_ctl &= ~SECONDARY_EXEC_ENABLE_INVPCID;
 
-		if (best)
-			best->ebx &= ~bit(X86_FEATURE_INVPCID);
+		guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
 	}
 
 	if (cpu_has_secondary_exec_ctrls())
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d75997ba65b9..9bba971fb51e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1021,21 +1021,11 @@ bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
 	if (efer & efer_reserved_bits)
 		return false;
 
-	if (efer & EFER_FFXSR) {
-		struct kvm_cpuid_entry2 *feat;
-
-		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
-		if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
+	if (efer & EFER_FFXSR && !guest_cpuid_has(vcpu, X86_FEATURE_FXSR_OPT))
 			return false;
-	}
 
-	if (efer & EFER_SVME) {
-		struct kvm_cpuid_entry2 *feat;
-
-		feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
-		if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
+	if (efer & EFER_SVME && !guest_cpuid_has(vcpu, X86_FEATURE_SVM))
 			return false;
-	}
 
 	return true;
 }
-- 
2.13.3