Re: [Xen-devel] Xen 4.3 development update RC2 imminent

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.05.13 at 16:58, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 21/05/13 15:55, Jan Beulich wrote:
>>>>> On 21.05.13 at 16:31, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>> On 21/05/13 15:06, Anthony PERARD wrote:
>>>> But then, once this applied, qxl is still not able to start. Xorg crash
>>>> (in the guest), and here is why:
>>>>
>>>> (XEN) emulate.c:88:d18 bad mmio size 16
>>>> (XEN) io.c:201:d18 MMIO emulation failed @ 0033:7fd2de390430: f3 0f 6f
>>>> 19 41 83 e8 403
>>>> (XEN) emulate.c:88:d18 bad mmio size 16
>>>> (XEN) io.c:201:d18 MMIO emulation failed @ 0033:7fd2de390430: f3 0f 6f
>>>> 19 41 83 e8 403
>>> Disassembly of section .data:
>>>
>>> 0000000000000000 <.data>:
>>>    0:    f3 0f 6f 19              movdqu (%rcx),%xmm3
>>>
>>> Xen does not support emulating SSE instructions.  We have sporadically
>>> seen similar errors from Windows guests.  The best guess I have managed
>>> to get so far is that %rcx is a pointer to something which Xen thinks is
>>> an MMIO page.
>>>
>>> In this case, it looks like X is copying from MMIO into an xmm register,
>>> scraping the framebuffer perhaps?  In the windows failure, it was the
>>> pagescrub trying to zero ram, which clearly indicated something wonky in
>>> the combined idea of the memory map.
>>>
>>> If Spice is doing something valid and sensible, then Xen will likely
>>> need extending to be able to emulate SSE instructions.
>> The emulator in the hypervisor can handle simple SSE instructions
>> like the above quite well. It's not immediately clear to me why
>> hvmemul_do_io() would need to limit the size to no more than a
>> long's width. Perhaps the data passing to the device model may
>> need adjustment to accommodate wider entities...
> 
> Ah yes - my mistake.  When I traced the code for my previous problem, it
> was actually a movntps instruction, which was specifically not emulated
> by Xen.  I incorrectly assumed that the same would apply to movqdu.

And again - where did you find MOVNTPS not being emulated?
Certainly not in -unstable?

Jan


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