Re: [Xen-devel] PTE Write access is not set

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.12.11 at 15:31, Liwei <xieliwei@xxxxxxxxx> wrote:
> ======First instance of VM Crash======
> Guest is openSuSE 11.4 on 2.6.37.6-0.5-desktop
> No symptoms in guest logs, logging just stopped.
> Looking at the serial logs, it appears that the guest just vapourised
> (unless the "First re-creation of guest" below is actually the first
> crash, though Jan and Tim mentioned that that crash couldn't have
> occurred during run-time).
> This VM has one part of the Intel 82575GB (0e:00.1) pass-throughed.
> 
> ++++First re-creation of guest++++
> xl create /etc/xen/vm-test4.cfg
> 
> ----Xen log----
> (XEN) HVM7: ata0-0: PCHS=16383/16/63 translation=lba LCHS=1024/255/63
> (XEN) HVM7: ata0 master: QEMU HARDDISK ATA-7 Hard-Disk ( 160 GBytes)
> (XEN) realmode.c:115:d7 Failed to emulate insn.
> (XEN) realmode.c:165:d7 Real-mode emulation failed @ a8c0:00005a8e: ff
> fa 00 15 99 2c
> (XEN) domain_crash called from realmode.c:166
> 
> ++++Second re-creation of guest++++
> xl create /etc/xen/vm-test4.cfg
> 
> (XEN) HVM8: ata0-0: PCHS=16383/16/63 translation=lba LCHS=1024/255/63
> (XEN) HVM8: ata0 master: QEMU HARDDISK ATA-7 Hard-Disk ( 160 GBytes)
> (XEN) realmode.c:115:d8 Failed to emulate insn.
> (XEN) realmode.c:165:d8 Real-mode emulation failed @ a8c0:0000fcb5: 72
> 5c 1b 80 c4 82
> (XEN) domain_crash called from realmode.c:166
> 
> [Did the same thing a few more times with similar results and gave up,
> rebooted dom0 and all was well]

So this suggests that the virtual firmware has a problem coming back
up with the passed through device still active (and the IOMMU may in
fact be shielding the rest of the system from bad effects of this).

This by itself is a problem, and the sudden death of the guest is
another (particularly if indeed there's no trace of that event in any
logs). Debugging this may be difficult for anyone who can't
reproduce it, so we'll have to rely on you providing more insight.
Enable more debugging/verbosity in the hypervisor and try again is
probably all I can suggest at this point.

Jan


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