PCIe switch upstream port may be one of the functions of a multifunction device. The resource distribution code does not take this into account properly and therefore it expands the upstream port resource windows too much, not leaving space for the other functions (in the multifunction device) and this leads to an issue that Jonathan reported. He runs QEMU with the following topoology (QEMU parameters): -device pcie-root-port,port=0,id=root_port13,chassis=0,slot=2 \ -device x3130-upstream,id=sw1,bus=root_port13,multifunction=on \ -device e1000,bus=root_port13,addr=0.1 \ -device xio3130-downstream,id=fun1,bus=sw1,chassis=0,slot=3 \ -device e1000,bus=fun1 The first e1000 NIC here is another function in the switch upstream port. This leads to following errors: pci 0000:00:04.0: bridge window [mem 0x10200000-0x103fffff] to [bus 02-04] pci 0000:02:00.0: bridge window [mem 0x10200000-0x103fffff] to [bus 03-04] pci 0000:02:00.1: BAR 0: failed to assign [mem size 0x00020000] e1000 0000:02:00.1: can't ioremap BAR 0: [??? 0x00000000 flags 0x0] Fix this by taking into account the possible multifunction devices when uptream port resources are distributed. Link: https://lore.kernel.org/linux-pci/20221014124553.0000696f@xxxxxxxxxx/ Reported-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- The previous version of the series can be found here: https://lore.kernel.org/linux-pci/20221103103254.30497-1-mika.westerberg@xxxxxxxxxxxxxxx/ Changes from v1: * Re-worded the commit message to hopefully explain the problem better * Added Link: to the bug report * Update the comment according to Bjorn's suggestion * Dropped the ->multifunction check * Use %#llx in log format. drivers/pci/setup-bus.c | 56 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 52 insertions(+), 4 deletions(-) diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index b4096598dbcb..f3f39aa82dda 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -1830,10 +1830,58 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus, * bridges below. */ if (hotplug_bridges + normal_bridges == 1) { - dev = list_first_entry(&bus->devices, struct pci_dev, bus_list); - if (dev->subordinate) - pci_bus_distribute_available_resources(dev->subordinate, - add_list, io, mmio, mmio_pref); + /* Upstream port must be the first */ + bridge = list_first_entry(&bus->devices, struct pci_dev, bus_list); + if (!bridge->subordinate) + return; + + /* + * It is possible to have switch upstream port as a part of a + * multifunction device. For this reason reduce the space + * available for distribution by the amount required by the + * peers of the upstream port. + */ + list_for_each_entry(dev, &bus->devices, bus_list) { + int i; + + if (dev == bridge) + continue; + + for (i = 0; i < PCI_NUM_RESOURCES; i++) { + const struct resource *dev_res = &dev->resource[i]; + resource_size_t dev_sz; + struct resource *b_res; + + if (dev_res->flags & IORESOURCE_IO) { + b_res = &io; + } else if (dev_res->flags & IORESOURCE_MEM) { + if (dev_res->flags & IORESOURCE_PREFETCH) + b_res = &mmio_pref; + else + b_res = &mmio; + } else { + continue; + } + + /* Size aligned to bridge window */ + align = pci_resource_alignment(bridge, b_res); + dev_sz = ALIGN(resource_size(dev_res), align); + + pci_dbg(dev, "%pR aligned to %#llx\n", dev_res, + (unsigned long long)dev_sz); + + if (dev_sz >= resource_size(b_res)) + memset(b_res, 0, sizeof(*b_res)); + else + b_res->end -= dev_sz; + + pci_dbg(bridge, "updated available to %pR\n", b_res); + } + } + + pci_bus_distribute_available_resources(bridge->subordinate, + add_list, io, mmio, + mmio_pref); return; } -- 2.35.1
