KVM: x86: introduce kvm_register_clear_available

Small refactoring that will be used in the next patch.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/kvm_cache_regs.h

@@ -55,6 +55,13 @@ static inline void kvm_register_mark_available(struct kvm_vcpu *vcpu,
 	__set_bit(reg, (unsigned long *)&vcpu->arch.regs_avail);
 }
 
+static inline void kvm_register_clear_available(struct kvm_vcpu *vcpu,
+					       enum kvm_reg reg)
+{
+	__clear_bit(reg, (unsigned long *)&vcpu->arch.regs_avail);
+	__clear_bit(reg, (unsigned long *)&vcpu->arch.regs_dirty);
+}
+
 static inline void kvm_register_mark_dirty(struct kvm_vcpu *vcpu,
 					   enum kvm_reg reg)
 {

arch/x86/kvm/svm/svm.c

@@ -3873,10 +3873,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 		vcpu->arch.apf.host_apf_flags =
 			kvm_read_and_reset_apf_flags();
 
-	if (npt_enabled) {
-		vcpu->arch.regs_avail &= ~(1 << VCPU_EXREG_PDPTR);
-		vcpu->arch.regs_dirty &= ~(1 << VCPU_EXREG_PDPTR);
-	}
+	if (npt_enabled)
+		kvm_register_clear_available(vcpu, VCPU_EXREG_PDPTR);
 
 	/*
 	 * We need to handle MC intercepts here before the vcpu has a chance to