From: "Raj, Ashok" <ashok.raj@intel.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Casey Leedom <leedom@chelsio.com>,
"herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Atul Gupta <atul.gupta@chelsio.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
Michael Werner <werner@chelsio.com>,
"dwmw2@infradead.org" <dwmw2@infradead.org>,
Harsh Jain <Harsh@chelsio.com>
Subject: Re: [PATCH] iommu/vt-d: Fix scatterlist offset handling
Date: Tue, 3 Oct 2017 12:36:53 -0700 [thread overview]
Message-ID: <20171003193653.GA244814@otc-nc-03> (raw)
In-Reply-To: <20170928154345.GA101272@otc-nc-03>
Hi Robin
I now see your patch and it does seem to be fix the problem.
On Thu, Sep 28, 2017 at 08:43:46AM -0700, Ashok Raj wrote:
> Hi Robin
>
>
> On Thu, Sep 28, 2017 at 05:59:11PM +0100, Robin Murphy wrote:
> > I hope our email server hasn't got blacklisted again... Said patch is
> > the top of this very thread we're replying on[1] - you were definitely
> > on cc :(
>
> (sg->dma_address + sg->dma_len) ----+
> sg->dma_address ---------+ |
> iov_pfn------+ | |
> | | |
> v v v
> iova: a b c d e f
> |--------|--------|--------|--------|--------|
> <...calculated....>
> [_____mapped______]
> pfn: 0 1 2 3 4 5
> |--------|--------|--------|--------|--------|
> ^ ^ ^
> | | |
> sg->page ----+ | |
> sg->offset --------------+ |
> (sg->offset + sg->length) ----------+
>
> The picture seems right. Looking at the code i'm not sure if i understand
> it correctly.
>
> pgoff = sg->offset & ~PAGE_MASK;
>
> this gets the offset past the start of page.
>
> sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + pgoff;
>
> this would set dma_address at b+off instead of starting at c+off correct?
I assumed align_nrpages() would allocate 2 pages when
the offset is over PAGE_SIZE, but it seems economical and only
allocates 1 page to cover just the sg->length bytes.
the pteval also seems correct now, since you changed to
sg_phys() that already accounts for sg->offset, so you
subtract pgoff.
- pteval = page_to_phys(sg_page(sg)) | prot;
+ pteval = (sg_phys(sg) - pgoff) | prot;
Cheers,
Ashok
next prev parent reply other threads:[~2017-10-03 22:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-28 14:14 [PATCH] iommu/vt-d: Fix scatterlist offset handling Robin Murphy
2017-09-28 16:17 ` Casey Leedom
2017-09-28 13:29 ` Raj, Ashok
2017-09-28 16:59 ` Robin Murphy
2017-09-28 15:43 ` Raj, Ashok
2017-10-03 19:36 ` Raj, Ashok [this message]
2017-09-29 8:14 ` Harsh Jain
2017-09-29 16:18 ` Casey Leedom
[not found] ` <e2c92d3a-3d5d-a0eb-7d5f-a9453e48cfd5@chelsio.com>
2017-10-03 22:22 ` Casey Leedom
2017-10-03 12:55 ` David Woodhouse
2017-10-03 18:05 ` Robin Murphy
2017-10-03 22:16 ` David Woodhouse
2017-10-04 11:18 ` Robin Murphy
2017-10-06 14:43 ` Joerg Roedel
2017-10-06 12:54 ` Raj, Ashok
2017-11-06 18:47 ` Jacob Pan
2017-11-15 23:54 ` Jacob Pan
2017-11-16 21:32 ` Alex Williamson
2017-11-16 21:09 ` Raj, Ashok
2017-11-17 16:18 ` Alex Williamson
2017-11-17 15:48 ` Raj, Ashok
2017-11-17 17:44 ` Casey Leedom
2017-11-17 18:09 ` Jacob Pan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171003193653.GA244814@otc-nc-03 \
--to=ashok.raj@intel.com \
--cc=Harsh@chelsio.com \
--cc=atul.gupta@chelsio.com \
--cc=dwmw2@infradead.org \
--cc=herbert@gondor.apana.org.au \
--cc=iommu@lists.linux-foundation.org \
--cc=leedom@chelsio.com \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robin.murphy@arm.com \
--cc=werner@chelsio.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).