iommu/vt-d: Fix passthrough mode with translation-disabled devices
authorDavid Woodhouse <David.Woodhouse@intel.com>
Mon, 11 May 2015 13:59:20 +0000 (14:59 +0100)
committerDavid Woodhouse <David.Woodhouse@intel.com>
Mon, 11 May 2015 13:59:20 +0000 (14:59 +0100)
commit4ed6a540fab8ea4388c1703b73ecfed68a2009d1
treedde73b1a39c9cc68e25480fb889834706f0cec4e
parentb787f68c36d49bb1d9236f403813641efa74a031
iommu/vt-d: Fix passthrough mode with translation-disabled devices

When we use 'intel_iommu=igfx_off' to disable translation for the
graphics, and when we discover that the BIOS has misconfigured the DMAR
setup for I/OAT, we use a special DUMMY_DEVICE_DOMAIN_INFO value in
dev->archdata.iommu to indicate that translation is disabled.

With passthrough mode, we were attempting to dereference that as a
normal pointer to a struct device_domain_info when setting up an
identity mapping for the affected device.

This fixes the problem by making device_to_iommu() explicitly check for
the special value and indicate that no IOMMU was found to handle the
devices in question.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@vger.kernel.org (which means you can pick up 18436afdc now too)
drivers/iommu/intel-iommu.c