It is possible to have PCIe switch upstream port 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. Reported-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- Hi, This is the formal patch that resulted from the discussion here: https://lore.kernel.org/linux-pci/20220905080232.36087-5-mika.westerberg@xxxxxxxxxxxxxxx/T/#m724289d0ee0c1ae07628744c283116e60efaeaf1 Only change from that version is that we loop through all resources of the multifunction device. drivers/pci/setup-bus.c | 63 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 59 insertions(+), 4 deletions(-) diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index b4096598dbcb..c8787b187ee4 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -1830,10 +1830,65 @@ 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 + * resources occupied by the other functions before + * distributing the rest. + */ + list_for_each_entry(dev, &bus->devices, bus_list) { + int i; + + if (dev == bridge) + continue; + + /* + * It should be multifunction but if not stop + * the distribution and bail out. + */ + if (!dev->multifunction) + return; + + 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
