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

[Atom2 <ariel.atom2@web2web.at>]

Hi Jan,
many thanks for your reply. Answers are further down inline.
Am 12.11.15 um 13:52 schrieb Jan Beulich:
>>>> On 12.11.15 at 02:08, <ariel.atom2@web2web.at> wrote:
>> After the upgrade HVM domUs appear to no longer work - regardless of the
>> dom0 kernel (tested with both 3.18.9 and 4.1.7 as the dom0 kernel); PV
>> domUs, however, work just fine as before on both dom0 kernels.
>>
>> xl dmesg shows the following information after the first crashed HVM
>> domU which is started as part of the machine booting up:
>> [...]
>> (XEN) Failed vm entry (exit reason 0x80000021) caused by invalid guest
>> state (0).
>> (XEN) ************* VMCS Area **************
>> (XEN) *** Guest State ***
>> (XEN) CR0: actual=0x0000000000000039, shadow=0x0000000000000011,
>> gh_mask=ffffffffffffffff
>> (XEN) CR4: actual=0x0000000000002050, shadow=0x0000000000000000,
>> gh_mask=ffffffffffffffff
>> (XEN) CR3: actual=0x0000000000800000, target_count=0
>> (XEN)      target0=0000000000000000, target1=0000000000000000
>> (XEN)      target2=0000000000000000, target3=0000000000000000
>> (XEN) RSP = 0x0000000000006fdc (0x0000000000006fdc)  RIP =
>> 0x0000000100000000 (0x0000000100000000)
> Other than RIP looking odd for a guest still in non-paged protected
> mode I can't seem to spot anything wrong with guest state.
> Considering that there was just a single HVM-related commit
> between the two releases (which looks completely unrelated) I
> wonder whether you're observing a problem that's a side effect
> of something else, e.g. a build system change (compiler update or
> alike). If that can be ruled out, I guess the only chance would be
> for you to bisect for the offending commit.
A few weeks ago there was an update of the gcc compiler from version 
4.8.5 to 4.9.3. The old version of XEN (i.e. 4.5.1) was compiled in 
August on gcc-4.8.5. The current version xen-4.5.2 was compiled 
yesterday and obviously used gcc-4.9.3.
I might try to re-compile with 4.8.5 again in case that makes any sense 
(gcc-4.8.5 is still installed in another slot on my system), but will 
first reply to Andrew as well.
>
> Are you observing this on more than one kind of system?
Unfortunately this system is currently my only XEN system and it was 
rock-solid over the last couple of years with virtually no down-time 
once it was up and running with various XEN and dom0 kernel versions.
>
> Jan
Many thanks Atom