On 4/17/21 7:17 AM, Paolo Bonzini wrote:
On 12/04/21 23:56, Krish Sadhukhan wrote:
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@xxxxxxxxxx>
The exit code is defined by AMD, we cannot change it.
The reason why I thought of this is that SVM implementation uses only
the lower half, as all AMD-defined exit code are handled therein only.
Is this still going to cause an issue ?
Paolo
---
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;
