From: Will Deacon <will@kernel.org>
Date: Tue, 2 Jul 2019 16:43:24 +0100
Subject: iommu/io-pgtable-arm: Remove redundant call to io_pgtable_tlb_sync()
Git-commit: f71da46719460acd5afa411e52dc8cdf1cb9b0ce
Patch-mainline: v5.4-rc1
References: bsc#1175713

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>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 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 0fc8dfab2abf..a62733c6a632 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -587,7 +587,6 @@ 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 161a7d56264d..0d6633921c1e 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -583,7 +583,6 @@ 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;
 	}