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Re: [Qemu-devel] [BUG] VM abort after migration
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [BUG] VM abort after migration |
Date: |
Mon, 8 Jul 2019 10:47:50 +0100 |
User-agent: |
Mutt/1.12.0 (2019-05-25) |
* 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.
Dave
> Thanks,
> Longpeng(Mike)
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [BUG] VM abort after migration, longpeng, 2019/07/03
- Re: [Qemu-devel] [BUG] VM abort after migration,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [BUG] VM abort after migration, Jason Wang, 2019/07/09
- Re: [Qemu-devel] [BUG] VM abort after migration, Longpeng (Mike), 2019/07/09
- Re: [Qemu-devel] [BUG] VM abort after migration, Jason Wang, 2019/07/09
- Re: [Qemu-devel] [BUG] VM abort after migration, Longpeng (Mike), 2019/07/10
- Re: [Qemu-devel] [BUG] VM abort after migration, Longpeng (Mike), 2019/07/27
- Re: [Qemu-devel] [BUG] VM abort after migration, Jason Wang, 2019/07/29