Re: [Xen-devel] [PATCH 1/5] xen/vm_event: Added support for XSETBV events

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Fri, May 8, 2015 at 2:09 PM, Razvan Cojocaru
<rcojocaru@xxxxxxxxxxxxxxx> wrote:
> On 05/08/2015 02:52 PM, Jan Beulich wrote:
>>>>> On 08.05.15 at 13:05, <tamas.lengyel@xxxxxxxxxxxx> wrote:
>>> On Fri, May 8, 2015 at 12:55 PM, Andrew Cooper
>>> <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> On 08/05/15 11:53, Tamas K Lengyel wrote:
>>>>> On Fri, May 8, 2015 at 11:10 AM, Andrew Cooper
>>>>> <andrew.cooper3@xxxxxxxxxx> wrote:
>>>>>> On 08/05/15 10:06, Razvan Cojocaru wrote:
>>>>>>> On 05/07/2015 09:03 PM, Andrew Cooper wrote:
>>>>>>>> In an effort to be architecture neutral, it might be an idea to have
>>>>>>>> something like
>>>>>>>>
>>>>>>>> struct vm_event_write_cr {
>>>>>>>>     uint64_t index;
>>>>>>>>     uint64_t old_val, new_val;
>>>>>>>> };
>>>>>>>>
>>>>>>>> And have a per-arch index of control registers, such as
>>>>>>>>
>>>>>>>> X86_CR0
>>>>>>>> X86_CR3
>>>>>>>> X86_CR4
>>>>>>>> X86_XCR0
>>>>>>>> ...
>>>>>>>> ARM32_$foo
>>>>> On ARM there are no "cr" registers so IMHO it would be better to
>>>>> rename the struct vm_event_write_register. Other than that this sounds
>>>>> like a good addition to the interface.
>>>>
>>>> But there are surely the concept of "control registers" ?
>>>>
>>>> (I have no knowledge in this area)
>>>>
>>>> ~Andrew
>>>
>>> (Re-adding xen-devel)
>>>
>>> Certainly, they are just not (necessarily) called "CR". For example,
>>> CR3 equivalent on ARM is TTBR1. So what I meant here is that naming
>>> the struct should not be x86 specific.
>>
>> In which case - vm_event_write_ctrlreg?
>
> Looks good. Of course, the underlying footwork will need to stay just as
> complicated - sync / enabled flags for each supported register, but the
> interface will be cleaner and there will be less repetition for
> xc_monitor_*() and hvm_event_*().
>
>
> Thanks,
> Razvan

Sounds good to me too.

Tamas

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