iommu/vt-d: Defer domain removal if device is assigned to a driver

When the BUS_NOTIFY_DEL_DEVICE event is received the device
might still be attached to a driver. In this case the domain
can't be released as the mappings might still be in use.

Defer the domain removal in this case until we receivce the
BUS_NOTIFY_UNBOUND_DRIVER event.

Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: stable@vger.kernel.org   # v3.15, v3.16
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index d1f5caad04f9..5619f264862d 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3869,6 +3869,14 @@ static int device_notifier(struct notifier_block *nb,
             action != BUS_NOTIFY_DEL_DEVICE)
                 return 0;
 
+        /*
+         * If the device is still attached to a device driver we can't
+         * tear down the domain yet as DMA mappings may still be in use.
+         * Wait for the BUS_NOTIFY_UNBOUND_DRIVER event to do that.
+         */
+        if (action == BUS_NOTIFY_DEL_DEVICE && dev->driver != NULL)
+                return 0;
+
         domain = find_domain(dev);
         if (!domain)
                 return 0;