iommu: Fix a boundary issue to avoid performance drop

[ Upstream commit 3431c3f660a39f6ced954548a59dba6541ce3eb1 ]

After the change of patch ("iommu: Switch gather->end to the
inclusive end"), the performace drops from 1600+K IOPS to 1200K in our
kunpeng ARM64 platform.
We find that the range [start1, end1) actually is joint from the range
[end1, end2), but it is considered as disjoint after the change,
so it needs more times of TLB sync, and spends more time on it.
So fix the boundary issue to avoid performance drop.

Fixes: 862c3715de8f ("iommu: Switch gather->end to the inclusive end")
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/1616643504-120688-1-git-send-email-chenxiang66@hisilicon.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d63d3e9cc7b678d2e007fa2e59bbf2b6e22fab11..3e82f0dce3cce8a11d2b70e7200122553fdecf98 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -546,7 +546,7 @@ static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
         * structure can be rewritten.
         */
        if (gather->pgsize != size ||
-           end < gather->start || start > gather->end) {
+           end + 1 < gather->start || start > gather->end + 1) {
                if (gather->pgsize)
                        iommu_iotlb_sync(domain, gather);
                gather->pgsize = size;