Re: XSAVE/XRSTOR crash resurgence in 4.3

[Ben Guthro <ben.guthro@gmail.com>]

On Jul 4, 2013, at 9:21 AM, Jan Beulich <JBeulich@suse.com> wrote:

>>>> On 03.07.13 at 16:02, Ben Guthro <ben@guthro.net> wrote:
>> We (XenClient Enterprise) recently updated our mainline development to
>> xen 4.3, and noticed that the xsave/xrstor bug that crashes 32bit
>> windows guests with the driver verifier enabled has re-emerged.
>>
>> From Mark Roddy:
>> "The DOMU crash from last nights run  has this signature in the crash dump:
>>
>> Interrupt Service Routine A30BC91C has changed extended thread context.
>> Context saved before executing ISR: 841C4380. Context saved after
>> executing ISR: 841C5040.
>
> So along with the two questions raised on IRC (Intel vs AMD CPU
> and whether in your successful testing the XSA-52 and -53 fixes
> were included), would it be possible to get the contents of the
> two memory blocks pointed to (assuming you have a dump from
> that crash)? I'd like to be certain that the situation is the same as
> earlier, i.e. both selector fields are holding zero in the "after"
> incarnation, as I still can't see what's wrong with the new code.

Mark and I are out until Monday (US holiday) - but I'll put this on my
list to follow up on then.

>
>> It looks like we lost the fix for the XSAVE/XRSTOR"
>
> If the above doesn't help, I may need to hand you a debugging
> patch, mainly to see whether the current guest word size
> determination is wrong in any way (as that's the main thing that
> changed from the version you tested to the one that got checked
> in, yet I continue to only see this as an improvement, not as
> something that could have broken things).

Ok.
Happy to test a debug patch, as well.

Ben

>
> Jan
>