From: Maciej W. Rozycki macro@orcam.me.uk
commit 0e32818397426a688f598f35d3bc762eca6d7592 upstream.
When pci_assign_resource() is unable to assign resources to a BAR, it uses pci_revert_fw_address() to fall back to a firmware assignment (if any). Previously pci_revert_fw_address() assumed all addresses could reach the device, but this is not true if the device is below a bridge that only forwards addresses within its windows.
This problem was observed on a Tyan Tomcat IV S1564D system where the BIOS did not assign valid addresses to several bridges and USB devices:
pci 0000:00:11.0: PCI-to-PCIe bridge to [bus 01-ff] pci 0000:00:11.0: bridge window [io 0xe000-0xefff] pci 0000:01:00.0: PCIe Upstream Port to [bus 02-ff] pci 0000:01:00.0: bridge window [io 0x0000-0x0fff] # unreachable pci 0000:02:02.0: PCIe Downstream Port to [bus 05-ff] pci 0000:02:02.0: bridge window [io 0x0000-0x0fff] # unreachable pci 0000:05:00.0: PCIe-to-PCI bridge to [bus 06-ff] pci 0000:05:00.0: bridge window [io 0x0000-0x0fff] # unreachable pci 0000:06:08.0: USB UHCI 1.1 pci 0000:06:08.0: BAR 4: [io 0xfce0-0xfcff] # unreachable pci 0000:06:08.1: USB UHCI 1.1 pci 0000:06:08.1: BAR 4: [io 0xfce0-0xfcff] # unreachable pci 0000:06:08.0: can't claim BAR 4 [io 0xfce0-0xfcff]: no compatible bridge window pci 0000:06:08.1: can't claim BAR 4 [io 0xfce0-0xfcff]: no compatible bridge window
During the first pass of assigning unassigned resources, there was not enough I/O space available, so we couldn't assign the 06:08.0 BAR and reverted to the firmware assignment (still unreachable). Reverting the 06:08.1 assignment failed because it conflicted with 06:08.0:
pci 0000:00:11.0: bridge window [io 0xe000-0xefff] pci 0000:01:00.0: no space for bridge window [io size 0x2000] pci 0000:02:02.0: no space for bridge window [io size 0x1000] pci 0000:05:00.0: no space for bridge window [io size 0x1000] pci 0000:06:08.0: BAR 4: no space for [io size 0x0020] pci 0000:06:08.0: BAR 4: trying firmware assignment [io 0xfce0-0xfcff] pci 0000:06:08.1: BAR 4: no space for [io size 0x0020] pci 0000:06:08.1: BAR 4: trying firmware assignment [io 0xfce0-0xfcff] pci 0000:06:08.1: BAR 4: [io 0xfce0-0xfcff] conflicts with 0000:06:08.0 [io 0xfce0-0xfcff]
A subsequent pass assigned valid bridge windows and a valid 06:08.1 BAR, but left the 06:08.0 BAR alone, so the UHCI device was still unusable:
pci 0000:00:11.0: bridge window [io 0xe000-0xefff] released pci 0000:00:11.0: bridge window [io 0x1000-0x2fff] # reassigned pci 0000:01:00.0: bridge window [io 0x1000-0x2fff] # reassigned pci 0000:02:02.0: bridge window [io 0x2000-0x2fff] # reassigned pci 0000:05:00.0: bridge window [io 0x2000-0x2fff] # reassigned pci 0000:06:08.0: BAR 4: assigned [io 0xfce0-0xfcff] # left alone pci 0000:06:08.1: BAR 4: assigned [io 0x2000-0x201f] ... uhci_hcd 0000:06:08.0: host system error, PCI problems? uhci_hcd 0000:06:08.0: host controller process error, something bad happened! uhci_hcd 0000:06:08.0: host controller halted, very bad! uhci_hcd 0000:06:08.0: HCRESET not completed yet! uhci_hcd 0000:06:08.0: HC died; cleaning up
If the address assigned by firmware is not reachable because it's not within upstream bridge windows, fail instead of assigning the unusable address from firmware.
[bhelgaas: commit log, use pci_upstream_bridge()] Link: https://bugzilla.kernel.org/show_bug.cgi?id=16263 Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203012338460.46819@angie.orcam.me... Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209211921250.29493@angie.orcam.me... Fixes: 58c84eda0756 ("PCI: fall back to original BIOS BAR addresses") Signed-off-by: Maciej W. Rozycki macro@orcam.me.uk Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org # v2.6.35+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/setup-res.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/drivers/pci/setup-res.c +++ b/drivers/pci/setup-res.c @@ -214,6 +214,17 @@ static int pci_revert_fw_address(struct
root = pci_find_parent_resource(dev, res); if (!root) { + /* + * If dev is behind a bridge, accesses will only reach it + * if res is inside the relevant bridge window. + */ + if (pci_upstream_bridge(dev)) + return -ENXIO; + + /* + * On the root bus, assume the host bridge will forward + * everything. + */ if (res->flags & IORESOURCE_IO) root = &ioport_resource; else