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 <[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>
---
target/i386/cpu.c | 4 ++++
1 file changed, 4 insertions(+)
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 {
--
2.26.2
