Re: [PATCH 2/4] XSAVE/XRSTOR: enable guest save/restore

[Weidong Han <weidong.han@intel.com>]

Keir Fraser wrote:
> On 31/08/2010 08:08, "Jan Beulich" <JBeulich@novell.com> wrote:
>
>   
>>> #define VGCF_I387_VALID                (1<<0)
>>> #define VGCF_IN_KERNEL                 (1<<2)
>>> #define _VGCF_i387_valid               0
>>>       
>> As Keir already indicated, you can't change the size of this structure.
>> I'd say that it was a mistake to include the FPU state directly here in
>> the first place - you'll have to invent a mechanism to (compatibly)
>> not make this a requirement anymore. E.g. use the reserved part of
>> fpu_ctxt to store a guest handle referring to the actual area: This
>> ought to work as (iirc) the structure is used as input only
>> (VCPUOP_initialize) outside of the tools, and the domctl interface is
>> allowed to change as long as you don't break compatibility with
>> stored data (saved guest images).
>>     
>
> I would agree but for the fact that it appears that XSAVE is only supported
> for HVM guests right now. Hence this whole rigmarole is actually currently
> pointless, since HVM guests do not initialise/save/restore the
> vcpu_guest_context structure. I think probably this bit of the patch could
> simply be dropped until PV support is added.
>
>  -- Keir
>
> I will send out other patches soon, and revise this patch later.
Regards,
Weidong
>  
>