Re: Hard and silent lock up since linux 3.14 with PCIe pass through (vfio)

[Andreas Hartmann <andihartmann@freenet.de>]

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Alex Williamson wrote:
> On Wed, 2014-10-22 at 18:22 +0200, Andreas Hartmann wrote:
>> Alex Williamson wrote:
>>> --- a/drivers/pci/pci.c
>>> +++ b/drivers/pci/pci.c
>>> @@ -3308,15 +3308,15 @@ static int __pci_dev_reset(struct pci_dev *dev, int prob
>>>         if (rc != -ENOTTY)
>>>                 goto done;
>>>  
>>> -       rc = pci_pm_reset(dev, probe);
>>> +       rc = pci_dev_reset_slot_function(dev, probe);
>>>         if (rc != -ENOTTY)
>>>                 goto done;
>>>  
>>> -       rc = pci_dev_reset_slot_function(dev, probe);
>>> +       rc = pci_parent_bus_reset(dev, probe);
>>>         if (rc != -ENOTTY)
>>>                 goto done;
>>>  
>>> -       rc = pci_parent_bus_reset(dev, probe);
>>> +       rc = pci_pm_reset(dev, probe);
>>>  done:
>>>         return rc;
>>>  }
>>
>> This way it's crashing with echo 1 > reset, too.
> 
> Ok, so it's somehow related to doing a bus reset with virtual channel
> save/restore while PM reset with VC save/restore works ok as apparently
> does bus reset without VC save/restore.  Let's try to do a manual bus
> reset so we can look at the post reset state of the device before the
> kernel tries to restore it.
> 
> First bind the target device 03:00.0 to pci-stub or vfio-pci so that we
> know it's not being used.
> 
> Next capture lspci -xxxx -s 3:00.0 so we have the starting state.
> 
> Then we'll do a bus reset using setpci:
> # setpci -s 00:05.0 3e.w=40:40
> <if you script this, wait at least 2ms here>
> # setpci -s 00:05.0 3e.w=00:40
> <wait 1 second here>
> 
> Now re-capture lspci -xxxx -s 3:00.0

The machine is booted w/ vfio bound to 3:00.0 as usual (now for testing
linux 3.14)

lspci -xxxx -s 3:00.0
setpci -s 00:05.0 3e.w=40:40
usleep 10
setpci -s 00:05.0 3e.w=00:40
sleep 1
lspci -xxxx -s 3:00.0

I didn't get the second lspci because the machine already was hanging.
The first output is attached completely.



Hope this helps,
thanks,
regards,
Andreas

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