Re: [Qemu-devel] [BUG] VM abort after migration

[Jason Wang]

On 2019/7/10 上午11:36, Longpeng (Mike) wrote:
> 在 2019/7/10 11:25, Jason Wang 写道:
> > On 2019/7/8 下午5:47, Dr. David Alan Gilbert wrote:
> > > * longpeng (address@hidden) wrote:
> > > > Hi guys,
> > > >
> > > > We found a qemu core in our testing environment, the assertion
> > > > 'assert(bus->irq_count[i] == 0)' in pcibus_reset() was triggered and
> > > > the bus->irq_count[i] is '-1'.
> > > >
> > > > Through analysis, it was happened after VM migration and we think
> > > > it was caused by the following sequence:
> > > >
> > > > *Migration Source*
> > > > 1. save bus pci.0 state, including irq_count[x] ( =0 , old )
> > > > 2. save E1000:
> > > >      e1000_pre_save
> > > >       e1000_mit_timer
> > > >        set_interrupt_cause
> > > >         pci_set_irq --> update pci_dev->irq_state to 1 and
> > > >                     update bus->irq_count[x] to 1 ( new )
> > > >       the irq_state sent to dest.
> > > >
> > > > *Migration Dest*
> > > > 1. Receive the irq_count[x] of pci.0 is 0 , but the irq_state of e1000 is 1.
> > > > 2. If the e1000 need change irqline , it would call to pci_irq_handler(),
> > > >     the irq_state maybe change to 0 and bus->irq_count[x] will become
> > > >     -1 in this situation.
> > > > 3. do VM reboot then the assertion will be triggered.
> > > >
> > > > We also found some guys faced the similar problem:
> > > > [1] https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg02525.html
> > > > [2] https://bugs.launchpad.net/qemu/+bug/1702621
> > > >
> > > > Is there some patches to fix this problem ?
> > > I don't remember any.
> > >
> > > > Can we save pcibus state after all the pci devs are saved ?
> > > Does this problem only happen with e1000? I think so.
> > > If it's only e1000 I think we should fix it - I think once the VM is
> > > stopped for doing the device migration it shouldn't be raising
> > > interrupts.
> >
> > I wonder maybe we can simply fix this by no setting ICS on pre_save() but
> > scheduling mit timer unconditionally in post_load().
> I also think this is a bug of e1000 because we find more cores with the same
> frame thease days.
>
> I'm not familiar with e1000 so hope someone could fix it, thanks. :)

Draft a path in attachment, please test.

Thanks


> > Thanks
> >
> >
> > > Dave
> > >
> > > > Thanks,
> > > > Longpeng(Mike)
> > > --
> > > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> > .

0001-e1000-don-t-raise-interrupt-in-pre_save.patch
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