diff options
author | Will Deacon <will@kernel.org> | 2019-07-02 18:43:07 +0300 |
---|---|---|
committer | Will Deacon <will@kernel.org> | 2019-07-24 15:32:33 +0300 |
commit | 6d1bcb957be2850e0776f24c289e1f87c256baeb (patch) | |
tree | 23f7869dc3b6b51170912972a0c5fa3b92417625 /drivers/iommu/iommu.c | |
parent | 5f9e832c137075045d15cd6899ab0505cfb2ca4b (diff) | |
download | linux-6d1bcb957be2850e0776f24c289e1f87c256baeb.tar.xz |
iommu: Remove empty iommu_tlb_range_add() callback from iommu_ops
Commit add02cfdc9bc ("iommu: Introduce Interface for IOMMU TLB Flushing")
added three new TLB flushing operations to the IOMMU API so that the
underlying driver operations can be batched when unmapping large regions
of IO virtual address space.
However, the ->iotlb_range_add() callback has not been implemented by
any IOMMU drivers (amd_iommu.c implements it as an empty function, which
incurs the overhead of an indirect branch). Instead, drivers either flush
the entire IOTLB in the ->iotlb_sync() callback or perform the necessary
invalidation during ->unmap().
Attempting to implement ->iotlb_range_add() for arm-smmu-v3.c revealed
two major issues:
1. The page size used to map the region in the page-table is not known,
and so it is not generally possible to issue TLB flushes in the most
efficient manner.
2. The only mutable state passed to the callback is a pointer to the
iommu_domain, which can be accessed concurrently and therefore
requires expensive synchronisation to keep track of the outstanding
flushes.
Remove the callback entirely in preparation for extending ->unmap() and
->iotlb_sync() to update a token on the caller's stack.
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/iommu/iommu.c')
-rw-r--r-- | drivers/iommu/iommu.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 0c674d80c37f..6d7b25fe2474 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1903,9 +1903,6 @@ static size_t __iommu_unmap(struct iommu_domain *domain, if (!unmapped_page) break; - if (sync && ops->iotlb_range_add) - ops->iotlb_range_add(domain, iova, pgsize); - pr_debug("unmapped: iova 0x%lx size 0x%zx\n", iova, unmapped_page); |