releases/3.0.1/pci-ari-is-a-pcie-v2-feature.patch

   1 From 864d296cf948aef0fa32b81407541572583f7572 Mon Sep 17 00:00:00 2001
   2 From: Chris Wright <chrisw@sous-sol.org>
   3 Date: Wed, 13 Jul 2011 10:14:33 -0700
   4 Subject: PCI: ARI is a PCIe v2 feature
   5
   6 From: Chris Wright <chrisw@sous-sol.org>
   7
   8 commit 864d296cf948aef0fa32b81407541572583f7572 upstream.
   9
  10 The function pci_enable_ari() may mistakenly set the downstream port
  11 of a v1 PCIe switch in ARI Forwarding mode.  This is a PCIe v2 feature,
  12 and with an SR-IOV device on that switch port believing the switch above
  13 is ARI capable it may attempt to use functions 8-255, translating into
  14 invalid (non-zero) device numbers for that bus.  This has been seen
  15 to cause Completion Timeouts and general misbehaviour including hangs
  16 and panics.
  17
  18 Acked-by: Don Dutile <ddutile@redhat.com>
  19 Tested-by: Don Dutile <ddutile@redhat.com>
  20 Signed-off-by: Chris Wright <chrisw@sous-sol.org>
  21 Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  23
  24 ---
  25  drivers/pci/pci.c |    7 ++++++-
  26  1 file changed, 6 insertions(+), 1 deletion(-)
  27
  28 --- a/drivers/pci/pci.c
  29 +++ b/drivers/pci/pci.c
  30 @@ -1905,7 +1905,7 @@ void pci_enable_ari(struct pci_dev *dev)
  31  {
  32         int pos;
  33         u32 cap;
  34 -       u16 ctrl;
  35 +       u16 flags, ctrl;
  36         struct pci_dev *bridge;
  37
  38         if (!pci_is_pcie(dev) || dev->devfn)
  39 @@ -1923,6 +1923,11 @@ void pci_enable_ari(struct pci_dev *dev)
  40         if (!pos)
  41                 return;
  42
  43 +       /* ARI is a PCIe v2 feature */
  44 +       pci_read_config_word(bridge, pos + PCI_EXP_FLAGS, &flags);
  45 +       if ((flags & PCI_EXP_FLAGS_VERS) < 2)
  46 +               return;
  47 +
  48         pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap);
  49         if (!(cap & PCI_EXP_DEVCAP2_ARI))
  50                 return;