From: Will Deacon <will@kernel.org> mainline inclusion from mainline-v5.4-rc1 commit f71da46719460acd5afa411e52dc8cdf1cb9b0ce category: bugfix bugzilla: 21306 CVE: NA ------------------------------------------------------------------------- Commit b6b65ca20bc9 ("iommu/io-pgtable-arm: Add support for non-strict mode") added an unconditional call to io_pgtable_tlb_sync() immediately after the case where we replace a block entry with a table entry during an unmap() call. This is redundant, since the IOMMU API will call iommu_tlb_sync() on this path and the patch in question mentions this: | To save having to reason about it too much, make sure the invalidation | in arm_lpae_split_blk_unmap() just performs its own unconditional sync | to minimise the window in which we're technically violating the break- | before-make requirement on a live mapping. This might work out redundant | with an outer-level sync for strict unmaps, but we'll never be splitting | blocks on a DMA fastpath anyway. However, this sync gets in the way of deferred TLB invalidation for leaf entries and is at best a questionable, unproven hack. Remove it. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> --- drivers/iommu/io-pgtable-arm-v7s.c | 1 - drivers/iommu/io-pgtable-arm.c | 1 - 2 files changed, 2 deletions(-) diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index 8454de93e356..3a43fa3982d5 100644 --- a/drivers/iommu/io-pgtable-arm-v7s.c +++ b/drivers/iommu/io-pgtable-arm-v7s.c @@ -598,7 +598,6 @@ static size_t arm_v7s_split_blk_unmap(struct arm_v7s_io_pgtable *data, } io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true); - io_pgtable_tlb_sync(&data->iop); return size; } diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index c6f8d749a566..a726ba694ee3 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -527,7 +527,6 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data, tablep = iopte_deref(pte, data); } else if (unmap_idx >= 0) { io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true); - io_pgtable_tlb_sync(&data->iop); return size; } -- 2.25.1