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>]

Andre Przywara wrote:
> Avi Kivity wrote:
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -1415,7 +1415,7 @@ static void do_cpuid_ent(struct 
>>> -        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 exception.
I kind of tricked myself here. Since the hypervisor bit is (well, 
mostly) not set in the host, it will always be removed from the guest. 
So we need an exception for this anyway.
So please drop this patch, I will come up with some QEMU solution for this.

Regards,
Andre.

> 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.
> 

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