KVM: SVM: Fix nested sel_cr0 intercept path with decode-assists

This patch fixes a bug in the nested-svm path when
decode-assists is available on the machine. After a
selective-cr0 intercept is detected the rip is advanced
unconditionally. This causes the l1-guest to continue
running with an l2-rip.
This bug was with the sel_cr0 unit-test on decode-assists
capable hardware.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/svm.c

@@ -2799,6 +2799,9 @@ static int cr_interception(struct vcpu_svm *svm)
 		case 0:
 			if (!check_selective_cr0_intercepted(svm, val))
 				err = kvm_set_cr0(&svm->vcpu, val);
+			else
+				return 1;
+
 			break;
 		case 3:
 			err = kvm_set_cr3(&svm->vcpu, val);