Re: [Xen-devel] Test if on newer xen all SSE2 and SSE3 instructions are effectively working

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 21/11/13 15:12, George Dunlap wrote:
> On Thu, Nov 21, 2013 at 10:52 AM, Fabio Fantoni <fabio.fantoni@xxxxxxx> 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.

All operations on regular RAM should be fine, and should have no Xen
interception.

~Andrew

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