From: Ahmed Naseef Date: Thu, 12 Mar 2026 16:53:32 +0000 (+0000) Subject: PCI: Prevent assignment to unsupported bridge windows X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92427ab4378faa168d6953d0f8574b8fc1edcc14;p=thirdparty%2Fkernel%2Fstable.git PCI: Prevent assignment to unsupported bridge windows Previously, pci_read_bridge_io() and pci_read_bridge_mmio_pref() unconditionally set resource type flags (IORESOURCE_IO or IORESOURCE_MEM | IORESOURCE_PREFETCH) when reading bridge window registers. For windows that are not implemented in hardware, this may cause the allocator to assign space for a window that doesn't exist. For example, the EcoNET EN7528 SoC Root Port doesn't support the prefetchable window, but since a downstream device had a prefetchable BAR, the allocator mistakenly assigned a prefetchable window: pci 0001:00:01.0: [14c3:0811] type 01 class 0x060400 PCIe Root Port pci 0001:00:01.0: PCI bridge to [bus 01-ff] pci 0001:00:01.0: bridge window [mem 0x28000000-0x280fffff]: assigned pci 0001:00:01.0: bridge window [mem 0x28100000-0x282fffff pref]: assigned pci 0001:01:00.0: BAR 0 [mem 0x28100000-0x281fffff 64bit pref]: assigned pci_read_bridge_windows() already detects unsupported windows by testing register writability and sets dev->io_window/pref_window accordingly. Check dev->io_window/pref_window so we don't set the resource flags for unsupported windows, which prevents the allocator from assigning space to them. After this commit, the prefetchable BAR is correctly allocated from the non-prefetchable window: pci 0001:00:01.0: bridge window [mem 0x28000000-0x281fffff]: assigned pci 0001:01:00.0: BAR 0 [mem 0x28000000-0x280fffff 64bit pref]: assigned Suggested-by: Bjorn Helgaas Link: https://lore.kernel.org/all/20260113210259.GA715789@bhelgaas/ Signed-off-by: Ahmed Naseef Signed-off-by: Caleb James DeLisle Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260312165332.569772-4-cjd@cjdns.fr --- diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index bccc7a4bdd794..4eacb741b4ec1 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -395,6 +395,9 @@ static void pci_read_bridge_io(struct pci_dev *dev, struct resource *res, unsigned long io_mask, io_granularity, base, limit; struct pci_bus_region region; + if (!dev->io_window) + return; + io_mask = PCI_IO_RANGE_MASK; io_granularity = 0x1000; if (dev->io_window_1k) { @@ -465,6 +468,9 @@ static void pci_read_bridge_mmio_pref(struct pci_dev *dev, struct resource *res, pci_bus_addr_t base, limit; struct pci_bus_region region; + if (!dev->pref_window) + return; + pci_read_config_word(dev, PCI_PREF_MEMORY_BASE, &mem_base_lo); pci_read_config_word(dev, PCI_PREF_MEMORY_LIMIT, &mem_limit_lo); base64 = (mem_base_lo & PCI_PREF_RANGE_MASK) << 16;