KVM: x86: Remove unneeded kvm_vcpu variable, guest_xcr0_loaded

The kvm_vcpu variable, guest_xcr0_loaded, is a waste of an 'int'
and a conditional branch.  VMX and SVM are the only users, and both
unconditionally pair kvm_load_guest_xcr0() with kvm_put_guest_xcr0()
making this check unnecessary. Without this variable, the predicates in
kvm_load_guest_xcr0 and kvm_put_guest_xcr0 should match.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Change-Id: I7b1eb9b62969d7bbb2850f27e42f863421641b23
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -811,22 +811,16 @@ EXPORT_SYMBOL_GPL(kvm_lmsw);
 void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu)
 {
 	if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
-			!vcpu->guest_xcr0_loaded) {
-		/* kvm_set_xcr() also depends on this */
-		if (vcpu->arch.xcr0 != host_xcr0)
-			xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
-		vcpu->guest_xcr0_loaded = 1;
-	}
+	    vcpu->arch.xcr0 != host_xcr0)
+		xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
 }
 EXPORT_SYMBOL_GPL(kvm_load_guest_xcr0);
 
 void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
 {
-	if (vcpu->guest_xcr0_loaded) {
-		if (vcpu->arch.xcr0 != host_xcr0)
-			xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
-		vcpu->guest_xcr0_loaded = 0;
-	}
+	if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
+	    vcpu->arch.xcr0 != host_xcr0)
+		xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
 }
 EXPORT_SYMBOL_GPL(kvm_put_guest_xcr0);
 

include/linux/kvm_host.h

@@ -278,7 +278,6 @@ struct kvm_vcpu {
 	struct mutex mutex;
 	struct kvm_run *run;
 
-	int guest_xcr0_loaded;
 	struct swait_queue_head wq;
 	struct pid __rcu *pid;
 	int sigset_active;