kvm: x86: Introduce KVM_REQ_LOAD_CR3

The KVM_REQ_LOAD_CR3 request loads the hardware CR3 using the
current root_hpa.

Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.h

@@ -85,6 +85,13 @@ static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
 	return kvm_mmu_load(vcpu);
 }
 
+static inline void kvm_mmu_load_cr3(struct kvm_vcpu *vcpu)
+{
+	/* set_cr3() should ensure TLB has been flushed */
+	if (VALID_PAGE(vcpu->arch.mmu.root_hpa))
+		vcpu->arch.mmu.set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
+}
+
 /*
  * Currently, we have two sorts of write-protection, a) the first one
  * write-protects guest page to sync the guest modification, b) another one is