[PATCH v2 1/9] PCI: Avoid restoring error values in config space

[Farhan Ali <alifm@linux.ibm.com>]

The current reset process saves the device's config space state before
reset and restores it afterward. However, when a device is in an error
state before reset, config space reads may return error values instead of
valid data. This results in saving corrupted values that get written back
to the device during state restoration. Add validation to prevent writing
error values to the device when restoring the config space state after
reset.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
---
 drivers/pci/pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b0f4d98036cd..0dd95d782022 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1825,6 +1825,9 @@ static void pci_restore_config_dword(struct pci_dev *pdev, int offset,
 	if (!force && val == saved_val)
 		return;
 
+	if (PCI_POSSIBLE_ERROR(saved_val))
+		return;
+
 	for (;;) {
 		pci_dbg(pdev, "restore config %#04x: %#010x -> %#010x\n",
 			offset, val, saved_val);
-- 
2.43.0