[Qemu-devel] [PATCH] target-i386: Set AMD alias bits after filtering CPUID data

[Eduardo Habkost]

QEMU complains about -cpu host on an AMD machine:
  warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 0]
For bits 0,1,3,4,5,6,7,8,9,12,13,14,15,16,17,23,24.

KVM_GET_SUPPORTED_CPUID and and x86_cpu_get_migratable_flags()
don't handle the AMD CPUID aliases bits, making
x86_cpu_filter_features() print warnings and clear those CPUID
bits incorrectly.

To avoid hacking x86_cpu_get_migratable_flags() to handle
CPUID_EXT2_AMD_ALIASES (just like the existing hack inside
kvm_arch_get_supported_cpuid()), simply move the
CPUID_EXT2_AMD_ALIASES code in x86_cpu_realizefn() after the
x86_cpu_filter_features() call.

This will probably make the CPUID_EXT2_AMD_ALIASES hack in
kvm_arch_get_supported_cpuid() unnecessary, too. The hack will be
removed in a follow-up patch after v2.6.0.

Reported-by: Radim Krčmář <address@hidden>
Tested-by: Radim Krčmář <address@hidden>
Signed-off-by: Eduardo Habkost <address@hidden>
---
 target-i386/cpu.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index ddae932..d0b5b69 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2897,6 +2897,14 @@ static void x86_cpu_realizefn(DeviceState *dev, Error 
**errp)
         env->cpuid_level = 7;
     }
 
+    if (x86_cpu_filter_features(cpu) && cpu->enforce_cpuid) {
+        error_setg(&local_err,
+                   kvm_enabled() ?
+                       "Host doesn't support requested features" :
+                       "TCG doesn't support requested features");
+        goto out;
+    }
+
     /* On AMD CPUs, some CPUID[8000_0001].EDX bits must match the bits on
      * CPUID[1].EDX.
      */
@@ -2907,14 +2915,6 @@ static void x86_cpu_realizefn(DeviceState *dev, Error 
**errp)
     }
 
 
-    if (x86_cpu_filter_features(cpu) && cpu->enforce_cpuid) {
-        error_setg(&local_err,
-                   kvm_enabled() ?
-                       "Host doesn't support requested features" :
-                       "TCG doesn't support requested features");
-        goto out;
-    }
-
 #ifndef CONFIG_USER_ONLY
     qemu_register_reset(x86_cpu_machine_reset_cb, cpu);
 
-- 
2.1.0