Re: [Xen-devel] [PATCH XTF] don't overrun memory object

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.01.17 at 11:51, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 23/01/17 10:45, Andrew Cooper wrote:
>> On 23/01/17 10:30, Jan Beulich wrote:
>>> Using MOVUPS on an 8-byte quantity is wrong. There's no need for memory
>>> accesses in any of the probe_*() functions anyway - switch them all to
>>> insns without any operands or with register ones.
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> So it is.
>>
>> The memory pointers were a leftover from trying to make this test not
>> use FEP (and therefore suitable for testing older Xen).
>>
>> IIRC, the problem was that even with a memory operand, hardware took
>> care of EM/MP/TS handling before taking a vmexit for MMIO emulation.
>>
>> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> and committed.
> Having said that, this currently regresses the test:
> 
> --- Xen Test Framework ---
> Environment: HVM 64bit (Long mode 4 levels)
> FPU Exception Emulation
> Testing x87
> Testing x87 wait
> Testing MMX
> Testing SSE
> Testing SSE (CR4.OSFXSR)
> Testing emulated x87
> Testing emulated x87 wait
> Testing emulated MMX
>   Expected nothing, got #UD (cr0: - )
>   Expected #NM, got #UD (cr0: TS)
>   Expected nothing, got #UD (cr0: MP)
>   Expected #NM, got #UD (cr0: MP TS)
> Testing emulated SSE
> Testing emulated SSE (CR4.OSFXSR)
> Test result: FAILURE
> 
> A secondary requirement (to not regress) is that the test only uses
> instructions present in the emulator in the past, which I chose as being
> the point when FEP got added (seeing as that is a hard dependency).

Ah, it didn't regress for me because I ran it on top of the SSE/AVX
emulation series.

> Would you be happy if I dropped all but the final hunk, i.e. retaining
> the use of fildq and movq ?

Well, FNOP has always been supported, so I see no reason to drop
that. How about replacing PXOR by MOVQ (but retaining the register
operands)? (And I not that I left MOVUPS in place in error - I had
really meant to make it XORPS, but this now means one less think for
you to adjust.)

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel