On 20-09-2017 15:42, Robin Murphy wrote: > On 20/09/17 09:01, Herbert Xu wrote: >> Harsh Jain <Harsh@xxxxxxxxxxx> wrote: >>> While debugging DMA mapping error in chelsio crypto driver we observed that when scatter/gather list received by driver has some entry with page->offset > 4096 (PAGE_SIZE). It starts giving DMA error. Without IOMMU it works fine. >> This is not a bug. The network stack can and will feed us such >> SG lists. >> >>> 2) It cannot be driver's responsibilty to update received sg entries to adjust offset and page >>> because we are not the only one who directly uses received sg list. >> No the driver must deal with this. Having said that, if we can >> improve our driver helper interface to make this easier then we >> should do that too. What we certainly shouldn't do is to take a >> whack-a-mole approach like this patch does. > AFAICS this is entirely on intel-iommu - from a brief look it appears > that all the IOVA calculations would handle the offset correctly, but > then __domain_mapping() blindly uses sg_page() for the physical address, > so if offset is larger than a page it would end up with the DMA mapping > covering the wrong part of the buffer. > > Does the diff below help? > > Robin. > > ----->8----- > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index b3914fce8254..2ed43d928135 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2253,7 +2253,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, > sg_res = aligned_nrpages(sg->offset, sg->length); > sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset; > sg->dma_length = sg->length; > - pteval = page_to_phys(sg_page(sg)) | prot; > + pteval = (sg_phys(sg) & PAGE_MASK) | prot; > phys_pfn = pteval >> VTD_PAGE_SHIFT; > } Robin, Still having following error with above change. [ 429.645492] DMAR: DRHD: handling fault status reg 2 [ 429.650847] DMAR: [DMA Write] Request device [02:00.4] fault addr f2682000 [t >
