vfio/pci: Lock upstream bridge for vfio_pci_core_disable()

The commit 7e89efc ("Lock upstream bridge for pci_reset_function()")
added locking of the upstream bridge to the reset function. To catch
paths that are not properly locked, the commit 920f646 ("Warn on
missing cfg_access_lock during secondary bus reset") added a warning
if the PCI configuration space was not locked during a secondary bus reset
request.

When a VFIO PCI device is released from userspace ownership, an attempt
to reset the PCI device function may be made. If so, and the upstream bridge
is not locked, the release request results in a warning:

   pcieport 0000:00:00.0: unlocked secondary bus reset via:
   pci_reset_bus_function+0x188/0x1b8

Add missing upstream bridge locking to vfio_pci_core_disable().

Fixes: 7e89efc ("PCI: Lock upstream bridge for pci_reset_function()")
Signed-off-by: Anthony Pighin <anthony.pighin@nokia.com>
Link: https://lore.kernel.org/r/BN0PR08MB695171D3AB759C65B6438B5D838DA@BN0PR08MB6951.namprd08.prod.outlook.com
Signed-off-by: Alex Williamson <alex@shazbot.org>

Author: Anthony Pighin (Nokia)

drivers/vfio/pci/vfio_pci_core.c

@@ -588,6 +588,7 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_enable);
 
 void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 {
+	struct pci_dev *bridge;
 	struct pci_dev *pdev = vdev->pdev;
 	struct vfio_pci_dummy_resource *dummy_res, *tmp;
 	struct vfio_pci_ioeventfd *ioeventfd, *ioeventfd_tmp;
@@ -694,12 +695,20 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 	 * We can not use the "try" reset interface here, which will
 	 * overwrite the previously restored configuration information.
 	 */
-	if (vdev->reset_works && pci_dev_trylock(pdev)) {
-		if (!__pci_reset_function_locked(pdev))
-			vdev->needs_reset = false;
-		pci_dev_unlock(pdev);
+	if (vdev->reset_works) {
+		bridge = pci_upstream_bridge(pdev);
+		if (bridge && !pci_dev_trylock(bridge))
+			goto out_restore_state;
+		if (pci_dev_trylock(pdev)) {
+			if (!__pci_reset_function_locked(pdev))
+				vdev->needs_reset = false;
+			pci_dev_unlock(pdev);
+		}
+		if (bridge)
+			pci_dev_unlock(bridge);
 	}
 
+out_restore_state:
 	pci_restore_state(pdev);
 out:
 	pci_disable_device(pdev);