[PATCH 2/7 v7] KVM: nSVM: Define an exit code to reflect consistency check failure

[Krish Sadhukhan <krish.sadhukhan@oracle.com>]

nested_svm_vmrun() returns SVM_EXIT_ERR both when consistency checks for
MSRPM fail and when merging the MSRPM of vmcb12 with that of KVM fails. These
two failures are different in that the first one happens during consistency
checking while the second happens after consistency checking passes and after
guest mode switch is done. In order to differentiate between the two types of
error conditions, define an exit code that can be used to denote consistency
check failures. This new exit code is similar to what nVMX uses to denote
consistency check failures. For nSVM, we will use the highest bit in the high
part of the EXIT_CODE field.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
---
 arch/x86/include/uapi/asm/svm.h | 1 +
 arch/x86/kvm/svm/nested.c       | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
index 554f75fe013c..b0a6550a23f5 100644
--- a/arch/x86/include/uapi/asm/svm.h
+++ b/arch/x86/include/uapi/asm/svm.h
@@ -111,6 +111,7 @@
 #define SVM_VMGEXIT_UNSUPPORTED_EVENT		0x8000ffff
 
 #define SVM_EXIT_ERR           -1
+#define	SVM_CONSISTENCY_ERR    1 << 31
 
 #define SVM_EXIT_REASONS \
 	{ SVM_EXIT_READ_CR0,    "read_cr0" }, \
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 8453c898b68b..ae53ae46ebca 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -606,7 +606,7 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 	if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save) ||
 	    !nested_vmcb_check_controls(&svm->nested.ctl)) {
 		vmcb12->control.exit_code    = SVM_EXIT_ERR;
-		vmcb12->control.exit_code_hi = 0;
+		vmcb12->control.exit_code_hi = SVM_CONSISTENCY_ERR;
 		vmcb12->control.exit_info_1  = 0;
 		vmcb12->control.exit_info_2  = 0;
 		goto out;
-- 
2.27.0