On Tue, Sep 29, 2015 at 02:25:24PM +0900, Tomasz Figa wrote: > This patch adds a new "flush" callback to iommu_ops, which is supposed > to perform any necessary flushes within given IOMMU domain to make any > changes to mappings of given area [iova; iova + size) be reflected to > IOMMU clients. > > The purpose is to let IOMMU drivers skip page-by-page flushes and > replace it with one flush of full address range on devices which support > it. > > Signed-off-by: Tomasz Figa <tfiga@xxxxxxxxxxxx> > --- > drivers/iommu/iommu.c | 33 ++++++++++++++++++++++++++++++--- > include/linux/iommu.h | 2 ++ > 2 files changed, 32 insertions(+), 3 deletions(-) I seem to remember that Rob Clark had proposed something like this back before it was decided to introduce the ->map_sg() callback instead. I can't find a reference to the discussion, so perhaps I'm misremembering but adding Rob Clark in case he has any recollection of why the outcome was what it was. > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c [...] > @@ -1389,6 +1410,7 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size) > unmapped += unmapped_page; > } > > + iommu_flush(domain, orig_iova, unmapped); > trace_unmap(orig_iova, size, unmapped); > return unmapped; > } > @@ -1419,19 +1441,24 @@ size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova, > if (!IS_ALIGNED(s->offset, min_pagesz)) > goto out_err; > > - ret = iommu_map(domain, iova + mapped, phys, s->length, prot); > + ret = __iommu_map(domain, iova + mapped, phys, s->length, prot); > if (ret) > goto out_err; > > mapped += s->length; > } > > + iommu_flush(domain, iova, mapped); > + > return mapped; > > out_err: > /* undo mappings already done */ > iommu_unmap(domain, iova, mapped); > > + /* flush in case part of our mapping already got cached */ > + iommu_flush(domain, iova, mapped); > + > return 0; > > } iommu_unmap() already does an iommu_flush(), so why flush again after iommu_unmap()? Thierry
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