Re: [Xen-devel] [PATCH] x86/HVM: use single (atomic) MOV for aligned emulated writes

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.01.2020 20:40, Jason Andryuk wrote:
> On Fri, Dec 27, 2019 at 11:09 AM Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx> wrote:
>>
>> On 20/12/2019 16:23, Jan Beulich wrote:
>>> On 16.09.2019 11:40, Jan Beulich wrote:
>>>> Using memcpy() may result in multiple individual byte accesses
>>>> (dependening how memcpy() is implemented and how the resulting insns,
>>>> e.g. REP MOVSB, get carried out in hardware), which isn't what we
>>>> want/need for carrying out guest insns as correctly as possible. Fall
>>>> back to memcpy() only for accesses not 2, 4, or 8 bytes in size.
>>>>
>>>> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>
>> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> Should xen/arch/x86/mm/shadow/hvm.c:hvm_emulate_write() be similarly changed?

Probably. Care to make a patch?

Jan

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