Messages in this thread | | | Date | Tue, 24 Nov 2020 11:05:21 +0000 | From | Will Deacon <> | Subject | Re: [PATCH] iommu: Improve the performance for direct_mapping |
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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?
Will
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