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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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).

Jan


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