x86/amd-iommu: Fix deassignment of a device from the pt_domain

Deassigning a device from the passthrough domain does not
work and breaks device assignment to kvm guests. This patch
fixes the issue.

Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 751ce73c6e1b..adb0ba025702 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -1511,9 +1511,11 @@ static void __detach_device(struct device *dev)
 
         /*
          * If we run in passthrough mode the device must be assigned to the
-         * passthrough domain if it is detached from any other domain
+         * passthrough domain if it is detached from any other domain.
+         * Make sure we can deassign from the pt_domain itself.
          */
-        if (iommu_pass_through && dev_data->domain == NULL)
+        if (iommu_pass_through &&
+            (dev_data->domain == NULL && domain != pt_domain))
                 __attach_device(dev, pt_domain);
 }