Re: [Xen-devel] [PATCH V2] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute

From: Jan Beulich
Date: Thu Nov 30 2017 - 03:27:56 EST


>>> On 29.11.17 at 18:38, <govinda.tatti@xxxxxxxxxx> wrote:
>>> In the case of bus or slot reset, our goal is to reset connected PCIe
>>> fabric/card/endpoint.
>>> The connected card/endpoint can be multi-function device. So, same
>>> walk-through and checking
>>> is needed irrespective of type of reset being used.
>> I don't follow: The scope of other devices/functions possibly
>> affected by a reset depends on the type of reset, doesn't it?
> For PCIe platforms, both slot and bus reset endup resetting all connected
> device/functions on thesecondary bus (behind the root-port or
> downstream-port).

According to my understanding this contradicts the comment
ahead of pci_reset_slot(), which talks of multiple slots per bus.
In such a setup, I can't see why resetting on slot would affect
other slots on the same bus. At the same time the comment
says that the slot reset may resolve to a bus one when there's
just a single slot on the bus.

Jan