Re: [PATCH resend] pci: ARI is a PCIe v2 feature

[Chris Wright <chrisw@sous-sol.org>]

* Jesse Barnes (jbarnes@virtuousgeek.org) wrote:
> On Wed, 13 Jul 2011 10:14:33 -0700
> Chris Wright <chrisw@sous-sol.org> wrote:
> 
> > The function pci_enable_ari() may mistakenly set the downstream port
> > of a v1 PCIe switch in ARI Forwarding mode.  This is a PCIe v2
> > feature, and with an SR-IOV device on that switch port believing the
> > switch above is ARI capable it may attempt to use functions 8-255,
> > translating into invalid (non-zero) device numbers for that bus.
> > This has been seen to cause Completion Timeouts and general
> > misbehaviour including hangs and panics.
> 
> Thanks Chris, your earlier one is still sitting in my queue, but I
> wasn't going to send it for 3.0 as it didn't seem that critical.  Do
> you think it is?  If so you can send it directly to Linus with my ack
> as I don't have anything else queued, or just wait until the merge
> window when it will be put into the stable tree as well.

Cool, just wanted to make sure it wasn't lost.  I think it's fine to
merge in next window and let it filter back to -stable.  While I've seen
it cause panics, it's not a regression and the conditions required are
very specific (possibly including buggy BIOS).

thanks,
-chris