On Tue, 2020-11-24 at 11:05 +0000, Will Deacon wrote: > On Tue, Nov 24, 2020 at 05:24:44PM +0800, Yong Wu wrote: > > On Mon, 2020-11-23 at 12:32 +0000, Will Deacon wrote: > > > On Fri, Nov 20, 2020 at 05:06:28PM +0800, Yong Wu wrote: > > > > + unmapped_sz = 0; > > > > + } > > > > + start += pg_size; > > > > + } > > > > + if (unmapped_sz) { > > > > + ret = iommu_map(domain, start, start, > > > > unmapped_sz, > > > > + entry->prot); > > > > > > Can you avoid this hunk by changing your loop check to something like: > > > > > > if (!phys_addr) { > > > map_size += pg_size; > > > if (addr + pg_size < end) > > > continue; > > > } > > > > Thanks for your quick review. I have fixed and tested it. the patch is > > simple. I copy it here. Is this readable for you now? > > > > > > --- 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); > > @@ -752,12 +753,21 @@ static int > > iommu_create_device_direct_mappings(struct iommu_group *group, > > phys_addr_t phys_addr; > > > > phys_addr = iommu_iova_to_phys(domain, addr); > > - if (phys_addr) > > - continue; > > + if (!phys_addr) { > > + map_size += pg_size; > > + if (addr + pg_size < end) > > + continue; > > + else > > You don't need the 'else' here ^^^ > > > + addr += pg_size; /*Point to End */ > > addr = end ? > > That said, maybe we could simplify this further by changing the loop bounds > to be: > > for (addr = start; addr <= end; addr += pg_size) > > and checking: > > if (!phys_addr && addr != end) { > map_size += pg_size; > continue; > } > > does that work?
It works but I think we can not check iommu_iova_to_phys(domain, end). We should add a "if", like: for (addr = start; addr <= end; addr += pg_size) { ... if (addr < end) { phys_addr = iommu_iova_to_phys(domain, addr); if (!phys_addr) { map_size += pg_size; continue; } } ... If you don't like this "if (addr < end)", then we have to add a "goto". like this: for (addr = start; addr <= end; addr += pg_size) { phys_addr_t phys_addr; if (addr == end) goto map_last; phys_addr = iommu_iova_to_phys(domain, addr); if (!phys_addr) { map_size += pg_size; continue; } map_last: if (!map_size) continue; ret = iommu_map(domain, addr - map_size, addr - map_size, map_size, entry->prot); if (ret) goto out; } Which one is better? > > Will > > _______________________________________________ > Linux-mediatek mailing list > linux-media...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-mediatek