iommu/vt-d: Fix no_iommu to disable platform opt-in

If user explicitly requests to disable iommu (via "iommu=off" or
"intel_iommu=off"), there is no reason to force enabling it due
to platform opt-in (for external-facing devices). User should be
aware of any security implication of doing so.

"intel_iommu=off" implements this policy by setting no_platform_optin
to skip platform opt-in in platform_optin_force_iommu().

However, "iommu=off" (no_iommu=1) doesn't set no_platform_optin
hence is broken in this aspect:

  - detect_intel_iommu() doesn't request ACS if no_iommu=1
  - platform_optin_force_iommu() forces iommu on if external-facing
    devices exist and no_platform_optin is not set

This leads to a bad configuration with ACS disabled while DMA
remapping is enabled.

Instead of setting no_platform_optin (will soon be removed) for
no_iommu=1, directly check no_iommu in platform_optin_force_iommu().

Fixes: 89a6079df791 ("iommu/vt-d: Force IOMMU on for platform opt in hint")
Cc: stable@vger.kernel.org
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

0 files changed, 0 insertions, 0 deletions