[PATCH 0/3] iommu/arm-smmu-v3: TLB invalidation for SVA

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

To support sharing page tables with the CPU, the SMMU can participate in
Broadcast TLB Maintenance (BTM), where TLB invalidate instructions from
the CPU are received by the SMMU. For platforms that do no implement BTM
[1], it is still possible to use SVA, by sending all TLB invalidations
through the command queue. Patch 2 implements this.

This series also enables SVA for platforms that do support BTM, as an
intermediate step because properly supporting BTM requires cooperating
with KVM to allocate VMIDs [2]. With BTM enabled, the SMMU applies
broadcast invalidations by VMID to any matching TLB entry, because there
is no distinction between private and shared VMIDs like there is for
ASIDs. Therefore a stage-2 domain will need a VMID that doesn't conflict
with one allocated by KVM (or use the one from the corresponding VM,
pinned).

These patches, along with the IOPF series [3] and the quirks [4], enable
SVA for the hisi accelerator that's already supported upstream. My quick
performance comparison between BTM and !BTM on that platform were
inconclusive. Doing invalidations via cmdq seemed to slightly reduce
performance of some heavy compression jobs, but there was too much noise
and not enough invalidations in my tests.

This series does not depend on the IOPF one [3].

[1] https://lore.kernel.org/linux-iommu/BY5PR12MB37641E84D516054387FEE330B3CC0@BY5PR12MB3764.namprd12.prod.outlook.com/
[2] https://lore.kernel.org/linux-iommu/20200522101755.GA3453945@myrica/
[3] https://lore.kernel.org/linux-iommu/20210121123623.2060416-1-jean-philippe@linaro.org/
[4] https://lore.kernel.org/linux-pci/1610960316-28935-1-git-send-email-zhangfei.gao@linaro.org/

Jean-Philippe Brucker (3):
  iommu/arm-smmu-v3: Split arm_smmu_tlb_inv_range()
  iommu/arm-smmu-v3: Make BTM optional for SVA
  iommu/arm-smmu-v3: Add support for VHE

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |   6 +
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  14 ++-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 104 ++++++++++++------
 3 files changed, 89 insertions(+), 35 deletions(-)

-- 
2.30.0

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