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PCI: ARI is a PCIe v2 feature

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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>
This commit is contained in:
Chris Wright 2011-07-13 10:14:33 -07:00 committed by Jesse Barnes
parent a8c7ef3187
commit 864d296cf9
1 changed files with 6 additions and 1 deletions
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7
drivers/pci/pci.c
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@ -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;