| From | Paul Gortmaker <> | Subject | [34-longterm 132/179] PCI: ARI is a PCIe v2 feature | Date | Mon, 14 May 2012 22:13:48 -0400 |
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From: Chris Wright <chrisw@sous-sol.org>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. -------------------
commit 864d296cf948aef0fa32b81407541572583f7572 upstream.
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.
Acked-by: Don Dutile <ddutile@redhat.com> Tested-by: Don Dutile <ddutile@redhat.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/pci/pci.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 8abe983..2326637 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1713,7 +1713,7 @@ void pci_enable_ari(struct pci_dev *dev) { int pos; u32 cap; - u16 ctrl; + u16 flags, ctrl; struct pci_dev *bridge; if (!pci_is_pcie(dev) || dev->devfn) @@ -1731,6 +1731,11 @@ void pci_enable_ari(struct pci_dev *dev) if (!pos) return; + /* ARI is a PCIe v2 feature */ + pci_read_config_word(bridge, pos + PCI_EXP_FLAGS, &flags); + if ((flags & PCI_EXP_FLAGS_VERS) < 2) + return; + pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap); if (!(cap & PCI_EXP_DEVCAP2_ARI)) return; -- 1.7.9.6
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