iommu: Improve the performance for direct_mapping (093b32a8) · Commits · 戴 / test

Currently direct_mapping always use the smallest pgsize which is SZ_4K normally to mapping. This is unnecessary. we could gather the size, and call iommu_map then, iommu_map could decide how to map better with the just right pgsize. >From the original comment, we should take care overlap, otherwise, iommu_map may return -EEXIST. In this overlap case, we should map the previous region before overlap firstly. then map the left part. Each a iommu device will call this direct_mapping when its iommu initialize, This patch is effective to improve the boot/initialization time especially while it only needs level 1 mapping. Signed-off-by:

Anan Sun <anan.sun@mediatek.com> Signed-off-by:

Yong Wu <yong.wu@mediatek.com> Link: https://lore.kernel.org/r/20201207093553.8635-1-yong.wu@mediatek.com Signed-off-by:

Will Deacon <will@kernel.org>

drivers/iommu/iommu.c

+17 −5

Original line number	Diff line number	Diff line
		@@ -739,6 +739,7 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
		/* We need to consider overlapping regions for different devices */
		list_for_each_entry(entry, &mappings, list) {
		dma_addr_t start, end, addr;
		size_t map_size = 0;

		if (domain->ops->apply_resv_region)
		domain->ops->apply_resv_region(dev, domain, entry);
		@@ -750,16 +751,27 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
		entry->type != IOMMU_RESV_DIRECT_RELAXABLE)
		continue;

		for (addr = start; addr < end; addr += pg_size) {
		for (addr = start; addr <= end; addr += pg_size) {
		phys_addr_t phys_addr;

		if (addr == end)
		goto map_end;

		phys_addr = iommu_iova_to_phys(domain, addr);
		if (phys_addr)
		if (!phys_addr) {
		map_size += pg_size;
		continue;
		}

		ret = iommu_map(domain, addr, addr, pg_size, entry->prot);
		map_end:
		if (map_size) {
		ret = iommu_map(domain, addr - map_size,
		addr - map_size, map_size,
		entry->prot);
		if (ret)
		goto out;
		map_size = 0;
		}
		}

		}

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