From 864d296cf948aef0fa32b81407541572583f7572 Mon Sep 17 00:00:00 2001 From: Chris Wright Date: Wed, 13 Jul 2011 10:14:33 -0700 Subject: [PATCH] PCI: ARI is a PCIe v2 feature 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. Cc: stable@kernel.org Acked-by: Don Dutile Tested-by: Don Dutile Signed-off-by: Chris Wright Signed-off-by: Jesse Barnes --- 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 692671b11667..d549bbc93cdd 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1905,7 +1905,7 @@ 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) @@ -1923,6 +1923,11 @@ 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; -- 2.39.5