From: Joerg Roedel <[email protected]>

Detaching a device from its domain at this event is
problematic for several reasons:

        * The device might me in an alias group and
          detaching it will also detach all other devices in
          the group. This removes valid DMA mappings from
          the other devices causing io-page-faults and lets
          these devices fail.

        * Devices might have unity mappings specified by the
          IVRS table. These mappings are required for the
          device even when no device driver is attached.
          Detaching the device from its domain in driver
          unbind will also remove these unity mappings.

This patch removes the handling of the BUS_NOTIFY_UNBOUND_DRIVER
event to prevent these issues and align it better with the
behavior of the VT-d driver.

Signed-off-by: Joerg Roedel <[email protected]>
---
 drivers/iommu/amd_iommu.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 8a1dea4..994cc7d 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2422,16 +2422,6 @@ static int device_change_notifier(struct notifier_block 
*nb,
        dev_data = get_dev_data(dev);
 
        switch (action) {
-       case BUS_NOTIFY_UNBOUND_DRIVER:
-
-               domain = domain_for_device(dev);
-
-               if (!domain)
-                       goto out;
-               if (dev_data->passthrough)
-                       break;
-               detach_device(dev);
-               break;
        case BUS_NOTIFY_ADD_DEVICE:
 
                iommu_init_device(dev);
-- 
1.9.1

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