Re: HVM domains crash after upgrade from XEN 4.5.1 to 4.5.2

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Atom2 <ariel.atom2@web2web.at>
Cc: Jan Beulich <JBeulich@suse.com>, xen-devel@lists.xen.org
Subject: Re: HVM domains crash after upgrade from XEN 4.5.1 to 4.5.2
Date: Mon, 16 Nov 2015 10:02:21 +0000	[thread overview]
Message-ID: <5649A9AD.9060809@citrix.com> (raw)
In-Reply-To: <564925B7.4090801@web2web.at>

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On 16/11/15 00:39, Atom2 wrote:
> Am 15.11.15 um 16:12 schrieb Andrew Cooper:
> [big snip]
>> Great - so confirms the issue as a SeaBIOS interaction issue, rather
>> than a hypervisor regression.
>>
>> As I said before, I am still certain that a guest should not be able
>> to get itself into the crashing state (short of a hardware errata),
>> so I still suspect that there is a latent hypervisor emulation bug
>> which has been tickled by the SeaBIOS update.
>>
>> Would you please mind running the bad HVMLoader on Xen 4.5.2 with
>> hvm_debug=0xc3f ? I am still hoping that that will shed some light on
>> SeaBIOS actions just leading up to the crash.
> Hi Andrew,
> Please see the attached two files. One is the dmesg from booting the
> system. This looks pretty normal in my view. The other is the output
> of "xl dmesg" which is most likely what you were after. It's probably
> worth noting that the "traps.c" output between lines 259 and 314 and
> again between lines 346 and 353 seem to be xen-4.5.2 specific and
> don't show up under xen-4.5.1, but that may not be of any relevance
> for the SeaBIOS issue we are experiencing. Though I'd still be
> interested to know whether that's anything for me to worry about ...

Sorry, but you need to be using a debug build of Xen.  The internals of
hvm_debug are not compiled in a regular build.

I am also only interested in `xl dmesg`.  There will be lots of log
lines prefixed with [HVM:$DOMID.$VCPUID].

>>
>> Are you able to experiment with newer versions of Xen?  It would be
>> interesting to see whether the issue is still present in Xen 4.6
> Currently xen-4.6 is not stable in gentoo and I try to stick to stable
> packages as much as possible. But in case the above does not help you
> any further, I am happy to give this a try as well. Would this just be
> a straightforward test to see whether it works at all or would you
> require debug symbols as well?

That's ok.  It is unlikely that this issue has been fixed since, so I
suspect that it is still present.

~Andrew

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