kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-09 18:15:49 +00:00
Code Issues Releases Packages Activity
linux/drivers/iommu/arm
History
Robin Murphy bad1a21944 iommu/arm-smmu: Report IOMMU_CAP_CACHE_COHERENCY even betterer 
commit ac9c5e92dd upstream.

Although it's vanishingly unlikely that anyone would integrate an SMMU
within a coherent interconnect without also making the pagetable walk
interface coherent, the same effect happens if a coherent SMMU fails to
advertise CTTW correctly. This turns out to be the case on some popular
NXP SoCs, where VFIO started failing the IOMMU_CAP_CACHE_COHERENCY test,
even though IOMMU_CACHE *was* previously achieving the desired effect
anyway thanks to the underlying integration.

While those SoCs stand to gain some more general benefits from a
firmware update to override CTTW correctly in DT/ACPI, it's also easy
to work around this in Linux as well, to avoid imposing too much on
affected users - since the upstream client devices *are* correctly
marked as coherent, we can trivially infer their coherent paths through
the SMMU as well.

Reported-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Fixes: df198b37e7 ("iommu/arm-smmu: Report IOMMU_CAP_CACHE_COHERENCY better")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/d6dc41952961e5c7b21acac08a8bf1eb0f69e124.1671123115.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-01-18 11:58:21 +01:00
..
arm-smmu iommu/arm-smmu: Report IOMMU_CAP_CACHE_COHERENCY even betterer 2023-01-18 11:58:21 +01:00
arm-smmu-v3 iommu/arm-smmu-v3: Don't unregister on shutdown 2023-01-18 11:58:20 +01:00
Makefile iommu/arm-smmu: Move Arm SMMU drivers into their own subdirectory 2020-07-27 12:53:10 +01:00