From a34d74877c66ce484ad586d806002ceaedd58657 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Thu, 3 Apr 2025 12:31:37 +0300
Subject: [PATCH] PCI: Restore assigned resources fully after release
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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
---
drivers/pci/setup-bus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 54d6f4fa3ce1..e994c546422c 100644
--- 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 @@ 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)