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

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.


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:
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
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:

--> 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:

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