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
>
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