Re: [PATCH 4/4] dont trim the guest's hypervisor CPUID bit in KVM if the guest requests it

[Andre Przywara <andre.przywara@amd.com>]

Avi Kivity wrote:
> On 06/24/2009 01:44 PM, Andre Przywara wrote:
>> Signed-off-by: Andre Przywara<andre.przywara@amd.com>
>> ---
>>   arch/x86/kvm/x86.c |    2 +-
>>   1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index e6e61ee..6ad0f93 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -1415,7 +1415,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 
>> *entry, u32 function,
>>           0 /* Reserved */ | F(CX16) | 0 /* xTPR Update, PDCM */ |
>>           0 /* Reserved, DCA */ | F(XMM4_1) |
>>           F(XMM4_2) | 0 /* x2APIC */ | F(MOVBE) | F(POPCNT) |
>> -        0 /* Reserved, XSAVE, OSXSAVE */;
>> +        0 /* Reserved, XSAVE, OSXSAVE */ | F(HYPERVISOR);
>>    
> 
> I think this should be handled in qemu, since it isn't really a cpu bit.

But this would require to make an exception for turning this bit on 
again after it has been trimmed.
I just made (QEMU) patches for make this trimming really work (and 
removing all the hacked bits), so I would like to not spoil this again 
by introducing another excecption. After all this is more a list of what 
KVM does _not_ support (should we make this a negative one? gets ugly 
with the reserved bits), so I would like to leave it here.
I will send out the patches to qemu-devel when I found the last bug.

Regards,
Andre.

-- 
Andre Przywara
AMD-OSRC (Dresden)
Tel: x29712