[PATCH 5.19 081/717] PCI: Sanitise firmware BAR assignments behind a PCI-PCI bridge

Greg Kroah-Hartman
2022-10-22T07:58:51Z

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.uk
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209211921250.29493@angie.orcam.me.uk
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