x86: svm: use cr_interception for SVM_EXIT_CR0_SEL_WRITE

Another patch in my war on emulate_on_interception() use as a svm exit handler.

These were pulled out of a larger patch at the suggestion of Radim Krcmar, see
https://lkml.org/lkml/2015/2/25/559

Changes since v1:
	* fixed typo introduced after test, retested
Signed-off-by: David Kaplan <david.kaplan@amd.com>
[separated out just cr_interception part from larger removal of
INTERCEPT_CR0_WRITE, forward ported, tested]
Signed-off-by: Joel Schopp <joel.schopp@amd.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/svm.c

@@ -2944,7 +2944,10 @@ static int cr_interception(struct vcpu_svm *svm)
 		return emulate_on_interception(svm);
 
 	reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
-	cr = svm->vmcb->control.exit_code - SVM_EXIT_READ_CR0;
+	if (svm->vmcb->control.exit_code == SVM_EXIT_CR0_SEL_WRITE)
+		cr = SVM_EXIT_WRITE_CR0 - SVM_EXIT_READ_CR0;
+	else
+		cr = svm->vmcb->control.exit_code - SVM_EXIT_READ_CR0;
 
 	err = 0;
 	if (cr >= 16) { /* mov to cr */
@@ -3328,7 +3331,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	[SVM_EXIT_READ_CR3]			= cr_interception,
 	[SVM_EXIT_READ_CR4]			= cr_interception,
 	[SVM_EXIT_READ_CR8]			= cr_interception,
-	[SVM_EXIT_CR0_SEL_WRITE]		= emulate_on_interception,
+	[SVM_EXIT_CR0_SEL_WRITE]		= cr_interception,
 	[SVM_EXIT_WRITE_CR0]			= cr_interception,
 	[SVM_EXIT_WRITE_CR3]			= cr_interception,
 	[SVM_EXIT_WRITE_CR4]			= cr_interception,