iommu: Improve the performance for direct_mapping
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>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index dd617ed..ae70a31 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -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;
- phys_addr = iommu_iova_to_phys(domain, addr);
- if (phys_addr)
- continue;
+ if (addr == end)
+ goto map_end;
- ret = iommu_map(domain, addr, addr, pg_size, entry->prot);
- if (ret)
- goto out;
+ phys_addr = iommu_iova_to_phys(domain, addr);
+ if (!phys_addr) {
+ map_size += pg_size;
+ continue;
+ }
+
+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;
+ }
}
}