On 19.02.21 14:10, Jan Beulich wrote:
> On 19.02.2021 13:48, Jürgen Groß wrote:
>> On 17.02.21 14:48, Marek Marczykowski-Górecki wrote:
>>> On Wed, Feb 17, 2021 at 07:51:42AM +0100, Jürgen Groß wrote:
>>>> On 17.02.21 06:12, Marek Marczykowski-Górecki wrote:
>>>>> Hi,
>>>>>
>>>>> I'm observing Linux PV/PVH guest crash when I resume it from sleep. I do
>>>>> this with:
>>>>>
>>>>>        virsh -c xen dompmsuspend <vmname> mem
>>>>>        virsh -c xen dompmwakeup <vmname>
>>>>>
>>>>> But it's possible to trigger it with plain xl too:
>>>>>
>>>>>        xl save -c <vmname> <some-file>
>>>>>
>>>>> The same on HVM works fine.
>>>>>
>>>>> This is on Xen 4.14.1, and with guest kernel 5.4.90, the same happens
>>>>> with 5.4.98. Dom0 kernel is the same, but I'm not sure if that's
>>>>> relevant here. I can reliably reproduce it.
>>>>
>>>> This is already on my list of issues to look at.
>>>>
>>>> The problem seems to be related to the XSA-332 patches. You could try
>>>> the patches I've sent out recently addressing other fallout from XSA-332
>>>> which _might_ fix this issue, too:
>>>>
>>>> https://patchew.org/Xen/20210211101616.13788-1-jgross@suse.com/
>>>
>>> Thanks for the patches. Sadly it doesn't change anything - I get exactly
>>> the same crash. I applied that on top of 5.11-rc7 (that's what I had
>>> handy). If you think there may be a difference with the final 5.11 or
>>> another branch, please let me know.
>>>
>>
>> Some more tests reveal that this seems to be s hypervisor regression.
>> I can reproduce the very same problem with a 4.12 kernel from 2019.
>>
>> It seems as if the EVTCHNOP_init_control hypercall is returning
>> -EINVAL when the domain is continuing to run after the suspend
>> hypercall (in contrast to the case where a new domain has been created
>> when doing a "xl restore").
> 
> But when you resume the same domain, the kernel isn't supposed to
> call EVTCHNOP_init_control, as that's a one time operation (per
> vCPU, and unless EVTCHNOP_reset was called of course). In the
> hypervisor map_control_block() has (always had) as its first step
> 
>      if ( v->evtchn_fifo->control_block )
>          return -EINVAL;
> 
> Re-setup is needed only when resuming in a new domain.

But the same guest will not crash when doing the same on a 4.12
hypervisor.


Juergen