pci: ARI is a PCIe v2 feature

PATCH Superseded Chris Wright 1 participant 1 message Jul 7, 2011 PCI

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Chris Wright

author

2011-07-07 23:25 UTC #0 lore raw

PATCH 1/1 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 [email protected]

Acked-by Don Dutile <[email protected]>

Tested-by Don Dutile <[email protected]>

Signed-off-by Chris Wright <[email protected]>

---

 drivers/pci/pci.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

drivers/pci/pci.c +6 -1

index 2c5b9b9..7f83236 100644
@@ -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;