linux-kernel - [PATCH 1/1] PCI: Restore assigned resources fully after release

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Message-Id: <20250403093137.1481-1-ilpo.jarvinen@linux.intel.com>
Date: Thu,  3 Apr 2025 12:31:37 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Guenter Roeck <linux@...ck-us.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Igor Mammedov <imammedo@...hat.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Michał Winiarski <michal.winiarski@...el.com>
Subject: [PATCH 1/1] 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.

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.

Reported-by: Guenter Roeck <linux@...ck-us.net>
Fixes: 96336ec70264 ("PCI: Perform reset_resource() and build fail list in sync")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.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)

base-commit: 7d06015d936c861160803e020f68f413b5c3cd9d
-- 
2.39.5