Re: [Xen-devel] [PATCH] x86_emulate: properly do IP updates and other side effects on success

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 11/08/14 14:16, Fabio Fantoni wrote:
> Il 11/08/2014 14:53, Fabio Fantoni ha scritto:
>> Il 07/08/2014 16:57, Fabio Fantoni ha scritto:
>>> Il 07/08/2014 16:38, Jan Beulich ha scritto:
>>>>>>> On 07.08.14 at 15:24, <fabio.fantoni@xxxxxxx> wrote:
>>>>> Il 07/08/2014 10:30, Jan Beulich ha scritto:
>>>>>> The two MMX/SSE/AVX code blocks failed to update IP properly, and
>>>>>> these
>>>>>> as well as get_reg_refix(), which "manually" updated IP so far,
>>>>>> failed
>>>>>> to do the TF and RF processing needed at the end of successfully
>>>>>> emulated instructions.
>>>>>>
>>>>>> Reported-by: Andrei LUTAS <vlutas@xxxxxxxxxxxxxxx>
>>>>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>>>>> Tested-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
>>>>> Thanks for the patch, I tested it to see if solves also qxl on linux
>>>>> domUs problem but with this patch the domU crashes and I cannot get a
>>>>> backtrace or specific errors.
>>>> Are you saying that this is different from without that patch?
>>>> Considering the lack of EIP update, the emulation of the
>>>> instructions in question can't have done much good before,
>>>> and - just like the reporters of the issue saw - the guest should
>>>> have hung.
>>>>
>>>> Jan
>>>>
>>>
>>> Before this patch the domU's org was always 100% cpu, spice show
>>> black screen and is possible a xl shutdown, after at xorg start,
>>> show domU's mouse in center in spice and domU crash.
>>> I'm unable to debug it, can you tell me what I must do to debug it
>>> and give you all possibile information?
>>>
>>> This is the exact git I used for my tests:
>>> https://github.com/Fantu/Xen/tree/rebase/m2r-staging
>>> Contains some libxl patch about spice used for a long time and with
>>> only qxl problem on linux domUs (with windows domUs is working good
>>> since your patch of long time ago about similar istructions and same
>>> performance as kvm after one or more patches in xen-unstable that I
>>> not know exactly and is still working also with this patch).
>>>
>>> Thanks for any reply and sorry for my bad english.
>>
>> Someone can tell me how to debug the domU's crash please?
>>
>> Thanks for any reply and sorry for my bad english.
>
> Now I did also a vcpus dump on domU preserved after crash if can be
> useful for this problem probably about cpu's instructions emulation:
> gdbsx -c 1 64
> ===> Context for DOMID:1
>
> --> VCPU:0

SHEDOP_shutdown.  Shutdown code in a structure at ffff880074803b3c

Looks like the VM has crashed.

~Andrew

> rip:ffffffff810013a8 rsp:ffff880074803b30 flags:0000000000000092
> rax:0000000000000000 rbx:00000000fffffffe rcx:00000000ffffffff
> rdx:ffffffff81edc300 rsi:ffff880074803b3c rdi:0000000000000002
> r08:0000000000000000 r09:0000000000000002 r10:ffffffff81d0a5e0
> r11:ffff8800748038c6 r12:ffffffff81c515c0 r13:0000000000000000
> r14:ffffffff81edc300 r15:0000000000000000 rbp:ffff880074803b40
> cs:0000000000000010 ds:0000000000000000 fs:0000000000000000
> gs:0000000000000000
>
> Call Trace:
>    [ffffffff810013a8]
>    [ffffffff8100357e]
>    [ffffffff810035a3]
>    [ffffffff816fa43c]
>    [ffffffff81a07727]
>    [ffffffff816fa49a]
>    [ffffffff816eb027]
>    [ffffffff810e17c8]
>    [ffffffff816f7603]
>    [ffffffff81a073db]
>    [ffffffff81016f9b]
>
> --> VCPU:1
> rip:ffffffff81053585 rsp:ffff880074823f88 flags:0000000000000046
> rax:ffffffff81c2a160 rbx:ffff88007342ffd8 rcx:00000006867023fa
> rdx:0000000000bad748 rsi:00000000000000ff rdi:00000000000000f0
> r08:00000000000000ac r09:0000000000000000 r10:0000000000000400
> r11:0000000000000001 r12:0000000000000001 r13:0000000000000000
> r14:ffff88007342c000 r15:ffff88007342ffd8 rbp:ffff880074823f88
> cs:0000000000000010 ds:0000000000000000 fs:0000000000000000
> gs:0000000000000000
>
> Call Trace:
>    [ffffffff81053585]
>    [ffffffff8101d70d]
>    [ffffffff810433b9]
>    [ffffffff8170005d]
>    [ffffffffffffffff]
>    [ffffffff810afd40]
>    [ffffffff8100a410]
>    [ffffffff8100a020]
>    [ffffffff81a06d7f]
>    [ffffffff8180b180]
>    [ffffffff81c2a858]
>
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