Re: [Xen-devel] [PATCH] xen: Add GS base to HVM VCPU context

[Aravindh Puthiyaparambil <aravindh@xxxxxxxxxxxx>]

On Mon, Apr 23, 2012 at 2:04 PM, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 23/04/2012 20:11, "Aravindh Puthiyaparambil" <aravindh@xxxxxxxxxxxx>
> wrote:
>
>>>>>> +#ifdef __x86_64__
>>>>>> +        if ( ring_0(&c.nat->user_regs) )
>>>>>> +            c.nat->gs_base_kernel = sreg.base;
>>>>>> +        else
>>>>>> +            c.nat->gs_base_user = sreg.base;
>>>>>> +#endif
>>>>>
>>>>> If you do anything like this, do it completely please (i.e. fill all three
>>>>> base address fields instead of just one).
>>>>>
>>>>
>>>> Sure. I was not sure if it was ok to add fields to the vcpu context
>>>> structure which is why I didn't do it across the board. I will do so and
>>>> resubmit.
>>>
>>> I don't see what fields you would need to add.
>>
>> Don't I need to add ss_base, cs_base, es_base, ds_base to
>> vcpu_guest_context? I am assuming both 32-bit and 64-bit cases.
>
> Only the existing (x86_64-only) fs_base, gs_base_kernel, gs_base_user fields
> need be filled in. All other base addresses are zero in 64-bit mode, and in
> 32-bit mode the base addresses are obtained from the GDT/LDT when the
> segment register is loaded, and so do not need to be stored in the
> vcpu_context.

Understood. I will resubmit with fs_based filled in.

Aravindh

>  -- Keir
>
>> Aravindh
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> http://lists.xen.org/xen-devel
>
>

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