PCI: Restore assigned resources fully after release

PCI resource fitting code in __assign_resources_sorted() runs in multiple
steps. A resource that was successfully assigned may have to be released
before the next step attempts assignment again. The assign+release cycle is
destructive to a start-aligned struct resource (bridge window or IOV
resource) because the start field is overwritten with the real address when
the resource got assigned.

One symptom:

  pci 0002:00:00.0: bridge window [mem size 0x00100000]: can't assign; bogus alignment

Properly restore the resource after releasing it. The start, end, and flags
fields must be stored into the related struct pci_dev_resource in order to
be able to restore the resource to its original state.

Fixes: 96336ec70264 ("PCI: Perform reset_resource() and build fail list in sync")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/r/01eb7d40-f5b5-4ec5-b390-a5c042c30aff@roeck-us.net/
Reported-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Closes: https://lore.kernel.org/r/3578030.5fSG56mABF@workhorse
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Ondrej Jirman <megi@xff.cz>
Link: https://patch.msgid.link/20250403093137.1481-1-ilpo.jarvinen@linux.intel.com

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 54d6f4fa3ce166ea4f62e4018c25f43ad3a4c8c3..e994c546422c9e8a52f62ef25b9a60367f4f5f9b 100644 (file)
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -187,6 +187,9 @@ static void pdev_sort_resources(struct pci_dev *dev, struct list_head *head)
                        panic("%s: kzalloc() failed!\n", __func__);
                tmp->res = r;
                tmp->dev = dev;
+               tmp->start = r->start;
+               tmp->end = r->end;
+               tmp->flags = r->flags;
 
                /* Fallback is smallest one or list is empty */
                n = head;
@@ -545,6 +548,7 @@ assign:
                pci_dbg(dev, "%s %pR: releasing\n", res_name, res);
 
                release_resource(res);
+               restore_dev_resource(dev_res);
        }
        /* Restore start/end/flags from saved list */
        list_for_each_entry(save_res, &save_head, list)