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@xxxxxxxxxx
Acked-by: Don Dutile <ddutile@xxxxxxxxxx>
Tested-by: Don Dutile <ddutile@xxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
drivers/pci/pci.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2c5b9b9..7f83236 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;
--
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