From: Casey Leedom <leedom@chelsio.com>
To: "Raj, Ashok" <ashok.raj@intel.com>
CC: Robin Murphy <robin.murphy@arm.com>,
        Dan Williams <dan.j.williams@intel.com>,
        "Harsh Jain" <Harsh@chelsio.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "dwmw2@infradead.org" <dwmw2@infradead.org>,
        Michael Werner <werner@chelsio.com>, "nd@arm.com" <nd@arm.com>
Subject: Re: DMA error when sg->offset value is greater than PAGE_SIZE in
 Intel IOMMU
Thread-Topic: DMA error when sg->offset value is greater than PAGE_SIZE in
 Intel IOMMU
Thread-Index: AQHTLrKuCX/YGlya50aETYTEmnILyqK9cAoAgAAkZQCACFcnkv//5CkAgAAvAguAAJgAAIAAj7QAgAAh/4CAABrJ6IAAA2oAgAGW6yaAAA4uAP//1k4AgABoxyT//9+SgAAGQBIW
Date: Wed, 27 Sep 2017 22:13:04 +0000
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| From: Raj, Ashok <ashok.raj@intel.com>
| Sent: Wednesday, September 27, 2017 12:07 PM
|
| looking at the debug output i got from Harsh it still looks like a bug in
| the code.
|
| [  538.284589] __domain_mapping nr_pages 0x1
| [ 538.284600] __domain_mapping sg_res 0x1 sg->dma_address 0xf291000e dma len
| 0x38 pteval 0x3cbce3003 phys_pfn 0x3cbce3
| [ 538.284604] chelsio driver - offset 4110 len 56 dma addr f291000e dma len
| 56
| [  538.284667] DMAR: DRHD: handling fault status reg 2
| [ 538.290017] DMAR: [DMA Write] Request device [02:00.4] fault addr f2910000
| [fault reason 05] PTE Write access is not set
|
| somehow when crypto_authenc_encrypt() -> scatterwalk_ffwd()-> sg_set_page()
|
| ->sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
|
| src->offset + len gets set as sg->offset in sg_set_page(). Either the
| assumption that there should be room is incorrect, or some higher order
| crypto
| code that ends up setting the offset did the wrong calculation.
|
| if src->offset is already towards the end of the page, then offset+len will
| go beyond the end of page.

  Hhmmm, it seems like we need Herbert to comment on this.

  Herbert, is there any specific debugging information that you'd like to
see here?

Casey