Re: [Xen-devel] [PATCH 2/2] xen: add update indicator to vcpu_runstate_info

[Juergen Gross <jgross@xxxxxxxx>]

On 20/05/16 17:36, Jan Beulich wrote:
>>>> On 20.05.16 at 17:04, <JGross@xxxxxxxx> wrote:
>> On 20/05/16 16:49, Jan Beulich wrote:
>>>>>> On 20.05.16 at 15:22, <JGross@xxxxxxxx> wrote:
>>>>      if ( guest_handle_is_null(runstate_guest(v)) )
>>>>          return 1;
>>>>  
>>>> +    update_flag = VM_ASSIST(v->domain, runstate_update_flag);
>>>> +
>>>>      smap_policy = smap_policy_change(v, SMAP_CHECK_ENABLED);
>>>>  
>>>> +    if ( update_flag )
>>>> +    {
>>>> +        off = offsetof(struct vcpu_runstate_info, state_entry_time) + 7;
>>>
>>> How come this is outside the following if()? Also sizeof(...) - 1 please
>>> instead of the literal 7.
>>
>> I'm using off for the source address in __raw_copy_to_guest(), too.
> 
> But the offset should, afaict, be different for 32-bit (x86) and
> 64-bit (or ARM).

Why? The offset is applied to v->runstate which clearly is the same
for 32 and 64 bit domains, as it is the hypervisor private structure.
Different offsets have to be applied at the destination side only, and
this is done properly (at least I think so).


Juergen


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