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

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Message-Id: <20241112134225.9837-1-ilpo.jarvinen@linux.intel.com>
Date: Tue, 12 Nov 2024 15:42:25 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Michał Winiarski <michal.winiarski@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Christian König <christian.koenig@....com>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH] 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.

Similarly, an assigned Expansion ROM resource prevents the resize.

Change the release loop to cover both the VF BARs and Expansion ROM
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: 8bb705e3e79d ("PCI: Add pci_resize_resource() for resizing BARs")
Reported-by: Michał Winiarski <michal.winiarski@...el.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 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 5d0f4db1cab7..80b01087d3ef 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1440,7 +1440,7 @@ 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);
-- 
2.39.5