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>
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@ -1905,7 +1905,7 @@ void pci_enable_ari(struct pci_dev *dev)
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{
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{
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int pos;
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int pos;
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u32 cap;
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u32 cap;
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u16 ctrl;
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u16 flags, ctrl;
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struct pci_dev *bridge;
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struct pci_dev *bridge;
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if (!pci_is_pcie(dev) || dev->devfn)
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if (!pci_is_pcie(dev) || dev->devfn)
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@ -1923,6 +1923,11 @@ void pci_enable_ari(struct pci_dev *dev)
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if (!pos)
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if (!pos)
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return;
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return;
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/* ARI is a PCIe v2 feature */
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pci_read_config_word(bridge, pos + PCI_EXP_FLAGS, &flags);
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if ((flags & PCI_EXP_FLAGS_VERS) < 2)
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return;
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pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap);
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pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap);
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if (!(cap & PCI_EXP_DEVCAP2_ARI))
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if (!(cap & PCI_EXP_DEVCAP2_ARI))
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return;
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return;
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