| Message ID | 20200623230116.277409-1-ehabkost@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | i386: Mask SVM features if nested SVM is disabled | expand |
diff --git a/target/i386/cpu.c b/target/i386/cpu.c index b1b311baa2..a9edcaf531 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1404,6 +1404,10 @@ static FeatureDep feature_dependencies[] = { .from = { FEAT_VMX_SECONDARY_CTLS, VMX_SECONDARY_EXEC_ENABLE_VMFUNC }, .to = { FEAT_VMX_VMFUNC, ~0ull }, }, + { + .from = { FEAT_8000_0001_ECX, CPUID_EXT3_SVM }, + .to = { FEAT_SVM, ~0ull }, + }, }; typedef struct X86RegisterInfo32 {
QEMU incorrectly validates FEAT_SVM feature flags against GET_SUPPORTED_CPUID even if SVM features are being masked out by cpu_x86_cpuid(). This can make QEMU print warnings on most AMD CPU models, even when SVM nesting is disabled (which is the default). This bug was never detected before because of a Linux KVM bug: until Linux v5.6, KVM was not filtering out SVM features in GET_SUPPORTED_CPUID when nested was disabled. This KVM bug was fixed in Linux v5.7-rc1, on Linux commit a50718cc3f43 ("KVM: nSVM: Expose SVM features to L1 iff nested is enabled"). Fix the problem by adding a CPUID_EXT3_SVM dependency to all FEAT_SVM feature flags in the feature_dependencies table. Reported-by: Yanan Fu <yfu@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- target/i386/cpu.c | 4 ++++ 1 file changed, 4 insertions(+)