iommu/amd: Put IOMMUv2 capable devices in pt_domain

If the device starts to use IOMMUv2 features the dma handles
need to stay valid. The only sane way to do this is to use a
identity mapping for the device and not translate it by the
iommu. This is implemented with this patch. Since this lifts
the device-isolation there is also a new kernel parameter
which allows to disable that feature.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 81c287fad79d..22152ed148a5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -329,6 +329,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                                     is a lot of faster
                         off       - do not initialize any AMD IOMMU found in
                                     the system
+                        force_isolation - Force device isolation for all
+                                          devices. The IOMMU driver is not
+                                          allowed anymore to lift isolation
+                                          requirements as needed. This option
+                                          does not override iommu=pt
 
         amijoy.map=     [HW,JOY] Amiga joystick support
                         Map of devices attached to JOY0DAT and JOY1DAT