• Jason Gunthorpe's avatar
    iommu: Fix false ownership failure on AMD systems with PASID activated · 2380f1e8
    Jason Gunthorpe authored
    The AMD IOMMU driver cannot activate PASID mode on a RID without the RID's
    translation being set to IDENTITY. Further it requires changing the RID's
    page table layout from the normal v1 IOMMU_DOMAIN_IDENTITY layout to a
    different v2 layout.
    
    It does this by creating a new iommu_domain, configuring that domain for
    v2 identity operation and then attaching it to the group, from within the
    driver. This logic assumes the group is already set to the IDENTITY domain
    and is being used by the DMA API.
    
    However, since the ownership logic is based on the group's domain pointer
    equaling the default domain to detect DMA API ownership, this causes it to
    look like the group is not attached to the DMA API any more. This blocks
    attaching drivers to any other devices in the group.
    
    In a real system this manifests itself as the HD-audio devices on some AMD
    platforms losing their device drivers.
    
    Work around this unique behavior of the AMD driver by checking for
    equality of IDENTITY domains based on their type, not their pointer
    value. This allows the AMD driver to have two IDENTITY domains for
    internal purposes without breaking the check.
    
    Have the AMD driver properly declare that the special domain it created is
    actually an IDENTITY domain.
    
    Cc: Robin Murphy <robin.murphy@arm.com>
    Cc: stable@vger.kernel.org
    Fixes: 512881ea ("bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management")
    Reported-by: default avatarTakashi Iwai <tiwai@suse.de>
    Tested-by: default avatarTakashi Iwai <tiwai@suse.de>
    Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
    Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
    Link: https://lore.kernel.org/r/0-v1-ea566e16b06b+811-amd_owner_jgg@nvidia.comSigned-off-by: default avatarJoerg Roedel <jroedel@suse.de>
    2380f1e8
iommu.c 81.4 KB