From 627f0ea6537ce7dc502100be65046c98bbf90b71 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Tue, 3 Feb 2026 19:21:38 +0200 Subject: [PATCH] PCI: Don't claim disabled bridge windows MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 2ecc1bf14e2fdaff78bd1b8e7ed3dba336a3fad5 ] The commit 8278c6914306 ("PCI: Preserve bridge window resource type flags") changed bridge window resource behavior such that flags are no longer zero if the bridge window is not valid or is disabled (mainly to preserve the type flags for later use). If a bridge window has its limit smaller than base address, pci_read_bridge_*() sets both IORESOURCE_UNSET and IORESOURCE_DISABLED to indicate the bridge window exists but is not valid with the current base and limit configuration. The code in pci_claim_bridge_resources() still depends on the old behavior of checking validity of the bridge window solely based on !r->flags, whereas after 8278c6914306, also IORESOURCE_DISABLED may indicate bridge window addresses are not valid. While pci_claim_resource() does check IORESOURCE_UNSET, pci_claim_bridge_resource() attempts to clip the resource if pci_claim_resource() fails, which is not correct for bridge window resources that are not valid. As pci_bus_clip_resource() performs clipping regardless of flags and then clears IORESOURCE_UNSET, it should not be called unless the resource is valid. The problem is visible in this log: pci 0000:20:00.0: PCI bridge to [bus 21] pci 0000:20:00.0: bridge window [io size 0x0000 disabled]: can't claim; no address assigned pci 0000:20:00.0: [io 0x0000-0xffffffffffffffff disabled] clipped to [io 0x0000-0xffff disabled] Add IORESOURCE_DISABLED check in pci_claim_bridge_resources() to only claim bridge windows that appear to have a valid configuration. Fixes: 8278c6914306 ("PCI: Preserve bridge window resource type flags") Reported-by: Sizhe Liu Link: https://lore.kernel.org/all/20260203023545.2753811-1-liusizhe5@huawei.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org Link: https://patch.msgid.link/4d9228d6-a230-6ddf-e300-fbf42d523863@linux.intel.com Signed-off-by: Sasha Levin --- drivers/pci/setup-bus.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 5d15298469cb..c2d640164f69 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -1681,6 +1681,8 @@ static void pci_claim_bridge_resources(struct pci_dev *dev) if (!r->flags || r->parent) continue; + if (r->flags & IORESOURCE_DISABLED) + continue; pci_claim_bridge_resource(dev, i); }