[PATCH 1/4] PCI: Reject all-ones responses in pci_dev_wait()

[Richard Cheng]

With RRS software visibility enabled, pci_dev_wait() treats an all-ones
Vendor ID response as reset completion, even though the device is
inaccessible.

Reject all-ones responses and continue polling. Use the existing
Command-register check for VFs, whose Vendor ID can legitimately read as
all ones.

Signed-off-by: Richard Cheng <icheng@xxxxxxxxxx>
---
 drivers/pci/pci.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b2879a6be5f8..6461274bdbcf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1248,10 +1248,10 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
 	 * If the device is below a Root Port with Configuration RRS
 	 * Software Visibility enabled, reading the Vendor ID returns a
 	 * special data value if the device responded with RRS.  Read the
-	 * Vendor ID until we get non-RRS status.
+	 * Vendor ID until we get neither RRS nor an error response.
 	 *
-	 * If there's no Root Port or Configuration RRS Software Visibility
-	 * is not enabled, the device may still respond with RRS, but
+	 * For VFs, or if there's no Root Port or Configuration RRS Software
+	 * Visibility is not enabled, the device may still respond with RRS, but
 	 * hardware may retry the config request.  If no retries receive
 	 * Successful Completion, hardware generally synthesizes ~0
 	 * (PCI_ERROR_RESPONSE) data to complete the read.  Reading Vendor
@@ -1266,9 +1266,9 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
 			return -ENOTTY;
 		}
 
-		if (root && root->config_rrs_sv) {
+		if (root && root->config_rrs_sv && !dev->is_virtfn) {
 			pci_read_config_dword(dev, PCI_VENDOR_ID, &id);
-			if (!pci_bus_rrs_vendor_id(id))
+			if (!PCI_POSSIBLE_ERROR(id) && !pci_bus_rrs_vendor_id(id))
 				break;
 		} else {
 			pci_read_config_dword(dev, PCI_COMMAND, &id);
-- 
2.43.0