linux-kernel - [PATCH v2 1/1] PCI: Fix BAR resizing when VF BARs are assigned

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Message-Id: <20250307140349.5634-1-ilpo.jarvinen@linux.intel.com>
Date: Fri,  7 Mar 2025 16:03:49 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Christian König <christian.koenig@....com>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Michał Winiarski <michal.winiarski@...el.com>
Subject: [PATCH v2 1/1] PCI: Fix BAR resizing when VF BARs are assigned

__resource_resize_store() attempts to release all resources of the
device before attempting the resize. The loop, however, only covers
standard BARs (< PCI_STD_NUM_BARS). If a device has VF BARs that are
assigned, pci_reassign_bridge_resources() finds the bridge window still
has some assigned child resources and returns -NOENT which makes
pci_resize_resource() to detect an error and abort the resize.

Change the release loop to cover all resources up to VF BARs which
allows the resize operation to release the bridge windows and attempt
to assigned them again with the different size.

As __resource_resize_store() checks first that no driver is bound to
the PCI device before resizing is allowed, SR-IOV cannot be enabled
during resize so it is safe to release also the IOV resources.

Fixes: 91fa127794ac ("PCI: Expose PCIe Resizable BAR support via sysfs")
Reported-by: Michał Winiarski <michal.winiarski@...el.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---

v2:
- Removed language about expansion ROMs

 drivers/pci/pci-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index b46ce1a2c554..0c16751bab40 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1578,7 +1578,7 @@ static ssize_t __resource_resize_store(struct device *dev, int n,

 	pci_remove_resource_files(pdev);

-	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) {
 		if (pci_resource_len(pdev, i) &&
 		    pci_resource_flags(pdev, i) == flags)
 			pci_release_resource(pdev, i);

base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
-- 
2.39.5