Commit 864d296c authored Jul 13, 2011 by Chris Wright Committed by Jesse Barnes Jul 22, 2011

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 <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>

parent a8c7ef31

drivers/pci/pci.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -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;