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....@mediatek.com> Signed-off-by: Yong Wu <yong...@mediatek.com> --- change notes: v2: Refine the code flow. v1: https://lore.kernel.org/linux-iommu/20201120090628.6566-1-yong...@mediatek.com/ base on v5.10-rc1. --- drivers/iommu/iommu.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 8c470f451a32..1a91decb95fa 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -737,6 +737,7 @@ 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); @@ -748,16 +749,27 @@ 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); - if (ret) - goto out; +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; + } } } -- 2.18.0
