On Wed, Sep 21, 2022 at 08:49:16PM +0100, Maciej W. Rozycki wrote: > Fix an issue with the Tyan Tomcat IV S1564D system, the BIOS of which > does not assign PCI buses beyond #2, where our resource reallocation > code preserves the reset default of an I/O BAR assignment outside its > upstream PCI-to-PCI bridge's I/O forwarding range: > > 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 0000:06:08.0: BAR 4: assigned [io 0xfce0-0xfcff] > [...] > pci_bus 0000:06: resource 0 [io 0x2000-0x2fff] > > Consequently when the device driver tries to access 06:08.0 according to > its designated address range it pokes at an unassigned I/O location, > likely subtractively decoded by the southbridge and forwarded to ISA, > causing the driver to become confused and bail out: > > 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 good luck happens or if bad luck does, an infinite flood of messages: > > uhci_hcd 0000:06:08.0: host system error, PCI problems? > uhci_hcd 0000:06:08.0: host controller process error, something bad happened! > > making the system virtually unusable. > > This is because we try to retain any BAR assignment the firmware may > have made here, which may be necessary for devices on the root bus with > some systems, but cannot work for devices that are behind a PCI-to-PCI > bridge where the BAR assignment is outside the upstream bridge's > forwarding range. > > Make sure then for a device behind a PCI-to-PCI bridge that any firmware > assignment is within the bridge's relevant forwarding window or do not > restore the assignment, fixing the system concerned as follows: > > pci 0000:06:08.0: BAR 4: no space for [io size 0x0020] > pci 0000:06:08.0: BAR 4: failed to assign [io 0xfce0-0xfcff] > [...] > pci 0000:06:08.0: BAR 4: assigned [io 0x2000-0x201f] > > and making device 06:08.0 work correctly. > > Cf. <https://bugzilla.kernel.org/show_bug.cgi?id=16263> > > Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx> > Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203012338460.46819@xxxxxxxxxxxxxxxxx > Fixes: 58c84eda0756 ("PCI: fall back to original BIOS BAR addresses") > Cc: stable@xxxxxxxxxxxxxxx # v2.6.35+ > --- > Hi Bjorn, > > I have trimmed the change description down as you requested and left the > change proper unmodified, as discussed in my earlier response. I think this is great. It shouldn't have taken me this long, so thanks for persevering. I think we can use pci_upstream_bridge() as below. Let me know if not. Here it is as I applied to pci/resource for v6.1: commit 0e3281839742 ("PCI: Sanitise firmware BAR assignments behind a PCI-PCI bridge") Author: Maciej W. Rozycki <macro@xxxxxxxxxxx> Date: Wed Sep 21 20:49:16 2022 +0100 PCI: Sanitise firmware BAR assignments behind a PCI-PCI bridge 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@xxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209211921250.29493@xxxxxxxxxxxxxxxxx Fixes: 58c84eda0756 ("PCI: fall back to original BIOS BAR addresses") Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v2.6.35+ diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c index 439ac5f5907a..b492e67c3d87 100644 --- a/drivers/pci/setup-res.c +++ b/drivers/pci/setup-res.c @@ -214,6 +214,17 @@ static int pci_revert_fw_address(struct resource *res, struct pci_dev *dev, 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
