KVM: x86: nSVM: restore the L1 host state prior to resuming nested guest on SMM exit

Otherwise guest entry code might see incorrect L1 state (e.g paging state).

Fixes: 37be407b ("KVM: nSVM: Fix L1 state corruption upon return from SMM")
Signed-off-by: NMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210913140954.165665-3-mlevitsk@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -4351,11 +4351,6 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 			if (svm_allocate_nested(svm))
 				return 1;
 
-			vmcb12 = map.hva;
-
-			nested_load_control_from_vmcb12(svm, &vmcb12->control);
-
-			ret = enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12);
 			kvm_vcpu_unmap(vcpu, &map, true);
 
 			/*
@@ -4369,6 +4364,13 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 			svm_copy_vmrun_state(&svm->vmcb01.ptr->save,
 					     map_save.hva + 0x400);
 
+			/*
+			 * Enter the nested guest now
+			 */
+			vmcb12 = map.hva;
+			nested_load_control_from_vmcb12(svm, &vmcb12->control);
+			ret = enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12);
+
 			kvm_vcpu_unmap(vcpu, &map_save, true);
 		}
 	}