iommu/vt-d: Use BUS_NOTIFY_REMOVED_DEVICE in hotplug path

In the PCI hotplug path of the Intel IOMMU driver, replace
the usage of the BUS_NOTIFY_DEL_DEVICE notifier, which is
executed before the driver is unbound from the device, with
BUS_NOTIFY_REMOVED_DEVICE, which runs after that.

This fixes a kernel BUG being triggered in the VT-d code
when the device driver tries to unmap DMA buffers and the
VT-d driver already destroyed all mappings.

Reported-by: Stefani Seibold <[email protected]>
Cc: [email protected] # v4.3+
Signed-off-by: Joerg Roedel <[email protected]>

Author: joergroedel

drivers/iommu/dmar.c

@@ -329,7 +329,8 @@ static int dmar_pci_bus_notifier(struct notifier_block *nb,
 	/* Only care about add/remove events for physical functions */
 	if (pdev->is_virtfn)
 		return NOTIFY_DONE;
-	if (action != BUS_NOTIFY_ADD_DEVICE && action != BUS_NOTIFY_DEL_DEVICE)
+	if (action != BUS_NOTIFY_ADD_DEVICE &&
+	    action != BUS_NOTIFY_REMOVED_DEVICE)
 		return NOTIFY_DONE;
 
 	info = dmar_alloc_pci_notify_info(pdev, action);
@@ -339,7 +340,7 @@ static int dmar_pci_bus_notifier(struct notifier_block *nb,
 	down_write(&dmar_global_lock);
 	if (action == BUS_NOTIFY_ADD_DEVICE)
 		dmar_pci_bus_add_dev(info);
-	else if (action == BUS_NOTIFY_DEL_DEVICE)
+	else if (action == BUS_NOTIFY_REMOVED_DEVICE)
 		dmar_pci_bus_del_dev(info);
 	up_write(&dmar_global_lock);
 

drivers/iommu/intel-iommu.c

@@ -4367,7 +4367,7 @@ int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info)
 				rmrru->devices_cnt);
 			if(ret < 0)
 				return ret;
-		} else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
+		} else if (info->event == BUS_NOTIFY_REMOVED_DEVICE) {
 			dmar_remove_dev_scope(info, rmrr->segment,
 				rmrru->devices, rmrru->devices_cnt);
 		}
@@ -4387,7 +4387,7 @@ int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info)
 				break;
 			else if(ret < 0)
 				return ret;
-		} else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
+		} else if (info->event == BUS_NOTIFY_REMOVED_DEVICE) {
 			if (dmar_remove_dev_scope(info, atsr->segment,
 					atsru->devices, atsru->devices_cnt))
 				break;