Re: [Xen-devel] XSAVE/XRSTOR crash resurgence in 4.3

[Ben Guthro <ben.guthro@xxxxxxxxx>]

On Fri, Jul 12, 2013 at 10:55 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 12.07.13 at 16:49, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>> On Fri, Jul 12, 2013 at 10:34 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>> On 12.07.13 at 15:49, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>>>> On Fri, Jul 12, 2013 at 9:38 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>>>> On 12.07.13 at 15:11, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>>>>>> The odd part is, that in this failing case - this machine does not
>>>>>> seem to be printing these debug messages at all.
>>>>>>
>>>>>> Is this the only path this can go through for xsave, or are there others?
>>>>>
>>>>> For xsave that's the only one. On systems not supporting xsave, it
>>>>> would go through the (not instrumented) fxsave path instead. But
>>>>> if we know that the system uses xsave, yet none of the messages
>>>>> gets printed, that's also a valuable piece of information.
>>>>
>>>> It at least has the xsave cpuid leaf in /proc/cpuinfo
>>>>
>>>> Is there something else in the Xen log I should look for to know that
>>>> Xen is actually using xsave?
>>>
>>>         printk("%s: using cntxt_size: %#x and states: %#"PRIx64"\n",
>>>             __func__, xsave_cntxt_size, xfeature_mask);
>>>
>>> (in xstate_init()).
>>
>>
>> (XEN) xstate_init: using cntxt_size: 0x340 and states: 0x7
>
> Okay, so to summarize: xsave is being used, and you don't see any
> of the messages from the debug patch printed, yet the Windows
> crash still occurs?

Yes - that is accurate.

The crash from this test run looked like the following

(from Mark)

STACK_COMMAND:  kb

FOLLOWUP_IP:
nt!ViCtxCheckAndReleaseXSaveData+59
8298120c cd2c            int     2Ch

Interrupt Service Routine 9AD1B91C has changed extended thread context.
Context saved before executing ISR: 841C5D80. Context saved after
executing ISR: 841C5B00.
1: kd> dd 841C5D80
841c5d80  0120027f 00000000 6dc42542 0000001b
841c5d90  6dc413c8 00000023 00001fa0 0000ffff
841c5da0  00d400d4 000000d4 0000ffff 00000000
841c5db0  009a9a9a 00000000 0000ffff 00000000
841c5dc0  00010001 00010001 0000ffff 00000000
841c5dd0  00000000 00000000 00000000 00000000
841c5de0  00000000 00000000 00000000 00000000
841c5df0  00000000 00000000 00008000 00000000
1: kd> dd 841C5B00
841c5b00  0120027f 00000000 6dc42542 00000000
841c5b10  6dc413c8 00000000 00001fa0 0000ffff
841c5b20  00d400d4 000000d4 0000ffff 00000000
841c5b30  009a9a9a 00000000 0000ffff 00000000
841c5b40  00010001 00010001 0000ffff 00000000
841c5b50  00000000 00000000 00000000 00000000
841c5b60  00000000 00000000 00000000 00000000
841c5b70  00000000 00000000 00008000 00000000


On other systems, with this same build, I see the debug output in the logs.

However, it is absent on this system

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