Re: [Xen-devel] Inconsistent use of libxl__device_pci_reset() when adding/removing all functions of a device

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Tuesday, February 4, 2014, 8:55:51 PM, you wrote:

> On Tue, Feb 04, 2014 at 07:19:16PM +0100, Martin Öhrling wrote:
>> I tried to use vga passthrough with an AMD card and ran into the issues
>> with dom0 crash on domU reboot. My intention is to debug the issue and I
>> have started to read up on the code for pci passthrough. The following
>> observations may not be an error but perhaps someone could shed some light
>> over the design intentions.
>> 
>> My first impression was that libxl__device_pci_reset() is a function level
>> reset function. It is called each time a single function of a device is
>> added or removed. A device reset would break other domU:s if other
>> functions of the device are passed through to these domU:s.
>> 
>> The strange thing is that there is only a single libxl__device_pci_reset()
>> call when pcidev->vfunc_mask is set to LIBXL_PCI_FUNC_ALL. I'm getting the
>> impression that the function is assumed to be a device reset function.
>> 
>> Is the attempt to reset a function, when all other functions belongs to
>> pciback, detected and replaced by a device reset?

> Yes with these patches:
> https://git.kernel.org/cgit/linux/kernel/git/konrad/xen.git/log/?h=devel/xen-pciback.slot_and_bus.v0

> But the last one seems to hang pciback when the device is unbound.

Another thing i'm seeing now sometimes is the "irq 16: nobody cared" after 
shutting down
a guest which has a pci device passed through, don't know for sure if that's 
only since
running with those 4 patches from that tree (could perhaps be due to that patch 
changing some order,
opening a very small race window there ..

But these patches do improve the other case in which it was crashing when using 
xl pci-assignable-remove.

>> 
>> Best Regards,
>> Martin

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>> http://lists.xen.org/xen-devel




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