Messages in this thread Patch in this message | | | From | Casey Leedom <> | Subject | Re: DMA error when sg->offset value is greater than PAGE_SIZE in Intel IOMMU | Date | Tue, 26 Sep 2017 20:50:02 +0000 |
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So just to be 100% sure I understand the patch you're proposing, you got the first use of VTD_PAGE_SHIFT wrong; it should have been VTD_PAGE_MASK? I.e.
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 6784a05..d43b566 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -2254,10 +2254,13 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, uint64_t tmp;
if (!sg_res) { + size_t off = sg->offset & ~VTD_PAGE_MASK; sg_res = aligned_nrpages(sg->offset, sg->length); - sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset; + sg->dma_address = ((dma_addr_t) + (iov_pfn + sg->offset) << VTD_PAGE_SHIFT) + off; sg->dma_length = sg->length; - pteval = page_to_phys(sg_page(sg)) | prot; + pteval = (page_to_phys(sg_page(sg)) + + (sg->offset << VTD_PAGE_SHIFT)) | prot; phys_pfn = pteval >> VTD_PAGE_SHIFT; }
??? And I'm still confused about this portion: - sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset; + sg->dma_address = ((dma_addr_t) + (iov_pfn + sg->offset) << VTD_PAGE_SHIFT) + off;
Isn't iov_pfn a Physical Page Number and we're adding a Byte Offset to that? I would have though that it would be more like:
size_t page_off = sg->offset & ~VTD_PAGE_MASK; unsigned long pfn_off = sg->offset >> VTD_PAGE_MASK; ... sg->dma_address = ((dma_addr_t) (iov_pfn + pfn_off) << VTD_PAGE_SHIFT) + page_off;
I want to be sure that Harsh has a concrete patch to work with when he wakes up.
How about it Robin, Dan, David, Herbert, what do you guys think of Raj's proposed patch?
Casey
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