[PATCH 0/2] iommu/arm-smmu-v3: Tegra264 invalidation workaround

[Ashish Mhetre]

Nvidia Tegra264 SMMUs are affected by an erratum where a TLB entry can
survive an invalidation that races with concurrent traffic targeting
the same entry. The hardware-recommended software workaround is to
issue every CFGI/TLBI command (each followed by CMD_SYNC) twice. The
second issue must execute only after the first issue's CMD_SYNC has
completed, giving the sequence:

    TLBI/CFGI ... CMD_SYNC TLBI/CFGI ... CMD_SYNC

This series implements the workaround by hooking the duplication into
the single chokepoint that every synchronous submission flows through
arm_smmu_cmdq_issue_cmdlist().

Patch 1 detects affected instances using the existing
"nvidia,tegra264-smmu" compatible string and exposes the condition
via a new ARM_SMMU_OPT_TLBI_TWICE option bit.

Patch 2 wires the option into the CMDQ submission path which is used to
re-issue the cmdlist when @sync is true and the first command is a
CFGI/TLBI.

Ashish Mhetre (2):
  iommu/arm-smmu-v3: Detect Tegra264 erratum
  iommu/arm-smmu-v3: Issue CFGI/TLBI twice on Tegra264

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 70 +++++++++++++++++++--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  8 +++
 2 files changed, 72 insertions(+), 6 deletions(-)


base-commit: f86b1ac9a67321419fec095ecb27584b2f77e339
-- 
2.50.1