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SubjectRe: DMA error when sg->offset value is greater than PAGE_SIZE in Intel IOMMU
Hey Raj,

Let us know if you need help in gathering more debugging information. For
the time being we've decided to ERRATA the use of the Intel I/O MMU with
IPsec till we Root Cause the issue. But this is still at the top of Harsh's
bug list.

With Robin's comments, I'm almost sure that the:

(iov_pfn + sg->offset) << VTD_PAGE_SHIFT)

in your suggested patch is an issue. iov_pfn is a Page Frame Number and
sg->offset is a Byte Offset. It feels like this should be:

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;

When Harsh tried your original patch, Harsh' test system wouldn't even boot.


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