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: 96336ec ("PCI: Perform reset_resource() and build fail list in sync")
Reported-by: Guenter Roeck <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]/
Reported-by: Nicolas Frattaroli <[email protected]>
Closes: https://lore.kernel.org/r/3578030.5fSG56mABF@workhorse
Signed-off-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Tested-by: Nicolas Frattaroli <[email protected]>
Tested-by: Guenter Roeck <[email protected]>
Tested-by: Ondrej Jirman <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: ij-intel

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 @@ static void __assign_resources_sorted(struct list_head *head,
 		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)