Re: [Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute

[Håkon Alstadheim <hakon@xxxxxxxxxxxxxxxxxx>]

Den 08. okt. 2018 16:32, skrev Boris Ostrovsky:
>
> Are these two patches still needed? ISTR they were  written originally
> to deal with guest trying to use device that was previously assigned to
> another guest. But pcistub_put_pci_dev() calls
> __pci_reset_function_locked() which first tries FLR, and it looks like
> it was added relatively recently.
>
>
Sorry for the late reply, but I just now booted xen staging-4.11
(94fba9f438a2c36ad9bf3a481a6013ddc7cf8cd9), with gentoo-sources-4.19.0
as dom0. Shut down and started again a VM that has a secondary GPU
passed through, and the whole  machine hung. I haven't had time to look
more closely into this, other than that my old "do_flr" patch no longer
applies to gentoo-sources (i.e. the linux kernel sources) . "do_flr"
worked for me on linux-4.18.? , with appropriate patch to the linux kernel.

So, something is definitely needed. No "reset" , or "do_flr" is present
in linux-4.19.0, viz:
<code>
$ cd /usr/src/linux/drivers/xen/xen-pciback
$ grep DRIVER *
pci_stub.c:#define PCISTUB_DRIVER_NAME "pciback"
pci_stub.c:          !strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) ||
pci_stub.c:     .name = PCISTUB_DRIVER_NAME,
pci_stub.c:static DRIVER_ATTR_WO(new_slot);
pci_stub.c:static DRIVER_ATTR_WO(remove_slot);
pci_stub.c:static DRIVER_ATTR_RO(slots);
pci_stub.c:static DRIVER_ATTR_RO(irq_handlers);
pci_stub.c:static DRIVER_ATTR_WO(irq_handler_state);
pci_stub.c:static DRIVER_ATTR_RW(quirks);
pci_stub.c:static DRIVER_ATTR_RW(permissive);
pci_stub.c:     if (action != BUS_NOTIFY_UNBIND_DRIVER)
$
</code>

I'd be happy to test patches. Seems I only got one corrupt file from my
test this morning :-D .


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