Re: Test if on newer xen all SSE2 and SSE3 instructions are effectively working

[Fabio Fantoni <fabio.fantoni@m2r.biz>]

Il 22/11/2013 13:16, Jan Beulich ha scritto:
>>>> On 22.11.13 at 13:14, Fabio Fantoni <fabio.fantoni@m2r.biz> wrote:
>> Il 21/11/2013 16:38, Andrew Cooper ha scritto:
>>> On 21/11/13 15:32, George Dunlap wrote:
>>>> On 21/11/13 15:22, Andrew Cooper wrote:
>>>>> On 21/11/13 15:12, George Dunlap wrote:
>>>>>> On Thu, Nov 21, 2013 at 10:52 AM, Fabio Fantoni
>>>>>> <fabio.fantoni@m2r.biz> wrote:
>>>>>>> I'm trying to test if on newer xen all SSE2 and SSE3 instructions are
>>>>>>> effectively working.
>>>>>>> I tried this simple program to test SSE2:
>>>>>>> http://forum.nasm.us/index.php?topic=1605.0
>>>>>>> But probably use only instructions with short operand because SSE2
>>>>>>> on this
>>>>>>> program is working also on old xen 4.0 where Jan Beulich patches to
>>>>>>> support
>>>>>>> long operands are missing.
>>>>>>> Are there any minimal program to test if SSE instructions with MMIO
>>>>>>> operands
>>>>>>>> 8 byte are working?
>>>>>> I don't see the code there doing MMIO -- it's just doing operations on
>>>>>> normal RAM, which is not emulated by Xen at all, but executed natively
>>>>>> by the processor.
>>>>>>
>>>>>> What you need is a program that will do this to an MMIO region -- that
>>>>>> will be a much trickier thing to set up, I think.
>>>>>>
>>>>>>     -George
>>>>> The problem with SSE is only when the guest performs an SSE (or larger)
>>>>> operation on a piece of memory which ends up being emulated and handed
>>>>> to qemu.  The ioreq protocol doesn't have a way of signalling an operand
>>>>> width greater than 64 bits.
>>>> I'd like to emphasize the "and" in the first sentence.  You might be
>>>> able to trigger a Xen emulation in any number of ways (disabling HAP
>>>> and then doing an SSE instruction on an in-use PT might do it).  But
>>>> Xen allegedly already does the actual emulation correctly -- as Andy
>>>> said, it's only the path to qemu that wasn't working before.
>>>>
>>>>    -George
>>>>
>>> Oops yes - I should have emphasised that a bit more.  I believe Jan
>>> submitted a hacked-fix for the qemu path which fixes the immediate issue
>>> (for 128bit emulation) but is in need of a redesign for wider emulation;
>>> 256bit is available with AVX, and 512bit is on its way with AVX2.
>>>
>>> As for testing individual instructions, there is
>>> tools/tests/x86_emulator/test_x86_emulator.c which tests a token few
>>> instructions against Xen's emulation code, but it is far from comprehensive.
>>>
>>> ~Andrew
>> Thanks for all replies.
>> I tried x86_emulator on dom0 and SSE2 instructions seems ok:
> Sure. Which means you still didn't understand that you need to
> try with SSE instructions accessing MMIO where the emulation
> happens in qemu.
>
> Jan
>

I have understood that this test needs to be tried inside hvm domUs (as 
I have posted in my previous mail):
> Same result on linux hvm domUs.

What I do not understand if is there is a test to accessing MMIO with 
SEE2 on x86_emulator and if not, an alternate way to make this check.

Thanks for any reply.