[Qemu-devel] [PATCH] Work around misreported kvm cpuid features

[Qemu-devel] [PATCH] Work around misreported kvm cpuid features

[Avi Kivity]

kvm misreports MCA, MCE, MTRR, and PAT as unsupported.  This causes Vista to
fail.  Since QEMU does not support any version of kvm that does not actually
support these features, it is safe to enable them unconditionally.

These features are needed by Vista x64 to boot.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 target-i386/kvm.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index fe67eed..a7b7ae3 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -88,6 +88,13 @@ uint32_t kvm_arch_get_supported_cpuid(CPUState *env, uint32_t function, int reg)
                 break;
             case R_EDX:
                 ret = cpuid->entries[i].edx;
+                if (function == 1) {
+                    /* kvm misreports the following features: */
+                    ret |= 1 << 12; /* MTRR */
+                    ret |= 1 << 16; /* PAT */
+                    ret |= 1 << 7;  /* MCE */
+                    ret |= 1 << 14; /* MCA */
+                }
                 if (function == 0x80000001) {
                     /* On Intel, kvm returns cpuid according to the Intel spec,
                      * so add missing bits according to the AMD spec:
-- 
1.6.1.1

Re: [Qemu-devel] [PATCH] Work around misreported kvm cpuid features

[Stuart Brady]

On Sun, May 10, 2009 at 03:45:05PM +0300, Avi Kivity wrote:
> These features are needed by Vista x64 to boot.

> +                    ret |= 1 << 12; /* MTRR */
> +                    ret |= 1 << 16; /* PAT */
> +                    ret |= 1 << 7;  /* MCE */
> +                    ret |= 1 << 14; /* MCA */

Just curious -- is there a reason to avoid the use of CPUID_MTRR,
CPUID_PAT, CPUID_MCE and CPUID_MCA here?

Cheers,
-- 
Stuart Brady

Re: [Qemu-devel] [PATCH] Work around misreported kvm cpuid features

[Avi Kivity]

Stuart Brady wrote:
> On Sun, May 10, 2009 at 03:45:05PM +0300, Avi Kivity wrote:
>   
>> These features are needed by Vista x64 to boot.
>>     
>
>   
>> +                    ret |= 1 << 12; /* MTRR */
>> +                    ret |= 1 << 16; /* PAT */
>> +                    ret |= 1 << 7;  /* MCE */
>> +                    ret |= 1 << 14; /* MCA */
>>     
>
> Just curious -- is there a reason to avoid the use of CPUID_MTRR,
> CPUID_PAT, CPUID_MCE and CPUID_MCA here?
>   

Didn't notice those.  Will send an updated patch.

-- 
error compiling committee.c: too many arguments to function