On Fri, Jul 09, 2021 at 12:34:59PM +0900, David Stevens wrote: > From: David Stevens <[email protected]> > > The is_swiotlb_buffer function takes the physical address of the swiotlb > buffer, not the physical address of the original buffer. The sglist > contains the physical addresses of the original buffer, so for the > sync_sg functions to work properly when a bounce buffer might have been > used, we need to use iommu_iova_to_phys to look up the physical address. > This is what sync_single does, so call that function on each sglist > segment. > > The previous code mostly worked because swiotlb does the transfer on map > and unmap. However, any callers which use DMA_ATTR_SKIP_CPU_SYNC with > sglists or which call sync_sg would not have had anything copied to the > bounce buffer. > > Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers") > Signed-off-by: David Stevens <[email protected]> > --- > drivers/iommu/dma-iommu.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 7bcdd1205535..eac65302439e 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -811,14 +811,14 @@ static void iommu_dma_sync_sg_for_cpu(struct device > *dev, > if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev)) > return; > > - for_each_sg(sgl, sg, nelems, i) { > - if (!dev_is_dma_coherent(dev)) > - arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir); > - > - if (is_swiotlb_buffer(sg_phys(sg))) > + if (dev_is_untrusted(dev)) > + for_each_sg(sgl, sg, nelems, i) > + iommu_dma_sync_single_for_cpu(dev, sg_dma_address(sg), > + sg->length, dir); > + else > + for_each_sg(sgl, sg, nelems, i) > swiotlb_sync_single_for_cpu(dev, sg_phys(sg), > sg->length, dir);
Doesn't this skip arch_sync_dma_for_cpu() for non-coherent trusted devices? Why not skip the extra dev_is_untrusted(dev) call here and just call iommu_dma_sync_single_for_cpu() for each entry regardless? Will _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
