tree 6d086adb09a29c116c17a13f02f4ca67383aed6b
parent 23f2b811bec6147c1fcb96a5593a313f99826354
author Yu Zhao <yuzhao@google.com> 1544132355 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1549997094 +0100

iommu/amd: Fix amd_iommu=force_isolation

[ Upstream commit c12b08ebbe16f0d3a96a116d86709b04c1ee8e74 ]

The parameter is still there but it's ignored. We need to check its
value before deciding to go into passthrough mode for AMD IOMMU v2
capable device.

We occasionally use this parameter to force v2 capable device into
translation mode to debug memory corruption that we suspect is
caused by DMA writes.

To address the following comment from Joerg Roedel on the first
version, v2 capability of device is completely ignored.
> This breaks the iommu_v2 use-case, as it needs a direct mapping for the
> devices that support it.

And from Documentation/admin-guide/kernel-parameters.txt:
  This option does not override iommu=pt

Fixes: aafd8ba0ca74 ("iommu/amd: Implement add_device and remove_device")

Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>