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

[Ben Guthro <ben.guthro@xxxxxxxxx>]

On Mon, Jul 8, 2013 at 11:10 AM, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
> On Mon, Jul 8, 2013 at 10:47 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>> On 08.07.13 at 16:42, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>>> On Jul 8, 2013, at 10:41 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>
>>>>>>> On 08.07.13 at 16:31, Ben Guthro <ben@xxxxxxxxxx> wrote:
>>>>> On Mon, Jul 8, 2013 at 10:24 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>>>>> On 08.07.13 at 16:13, Ben Guthro <ben@xxxxxxxxxx> wrote:
>>>>>>> On Fri, Jul 5, 2013 at 8:58 AM, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>>>>>>>> On Jul 5, 2013, at 8:15 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>>>>
>>>>>>>>>>>> On 05.07.13 at 14:10, Ben Guthro <ben.guthro@xxxxxxxxx> wrote:
>>>>>>>>>> Since I am not in the office today, nor near a machine that I can
>>>>>>>>>> access this, I asked someone else to apply and check in this patch, 
>>>>>>>>>> in
>>>>>>>>>> the hope that we could get some useful debug info from the weekend
>>>>>>>>>> test run.
>>>>>>>>>>
>>>>>>>>>> However, when he went to test booting a VM with this patch, the host
>>>>>>>>>> machine rebooted - presumably a Xen crash.
>>>>>>>>>
>>>>>>>>> Oops - it's just printing stuff, so I can't immediately see how that
>>>>>>>>> would happen. But perhaps a trivial oversight of mine...
>>>>>>>
>>>>>>> Here's the crash with this patch
>>>>>>> I'm continuing to look at it, but if something jumps out at you,
>>>>>>> please let me know.
>>>>>>
>>>>>> Quite obvious: hvm_guest_x86_mode() has this assertion. Yet
>>>>>> the original, supposedly working patch had a use of this too iirc.
>>>>>
>>>>> It did...which is worrying.
>>>>>
>>>>> One difference here, is that 4.2 is running in debug=n mode, where 4.3
>>>>> is debug=y
>>>>>
>>>>> iirc, asserts are disabled on debug=n builds.
>>>>
>>>> Oh, right. And in the context here the assertion triggering is
>>>> apparently wrong anyway. For the purpose of debugging the
>>>> issue at hand, I think it is safe to comment it out.
>>>
>>> Ok, I'll do that, thanks
>>
>> Or, perhaps better, replace the call in the patch with one to
>> hvmfuncs.guest_x86_mode(). That's what I have done in my
>> copy of the patch just now (in case we need a second rev at
>> some point).
>>
>
> Good idea. I'm testing a patch now, and will get it into tonight's test run.
> Hopefully I'll have some data to share tomorrow morning.

Due to some other breakage in our mainline build that just got fixed,
I just now got to analyze the logs for a system that showed this crash
with the debugging patch.
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?

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