mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: "Thomas Hellström (VMware)" <thomas_os@shipmail.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Christian König" <deathsimple@vodafone.de>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: DMA, TTM and memory encryption
Date: Mon, 16 Mar 2020 16:24:31 +0100	[thread overview]
Message-ID: <3d2317cd-bc40-47cb-3dae-8caa80acd767@shipmail.org> (raw)

Hi, Christoph,

It would be good to revisit this to see if we could set a direction for 
supporting user-space mapping of dma-coherent memory with TTM.

I think in the end, what TTM needs is a DMA interface similar to the one 
outlined here:

https://lore.kernel.org/lkml/b811f66d-2353-23c6-c9fa-e279cdb0f832@shipmail.org/

That could without too much effort be implemented for all architectures 
TTM supports and also for those weird architectures you've described 
that need special treatment, it would probably suffice with a more 
elaborate definition of the dma_pfn_t together with the dma coherent 
fault work you were suggesting earlier.

Regardless, once this patchset is in,

https://lore.kernel.org/lkml/20200304114527.3636-1-thomas_os@shipmail.org/

a short term solution would be to export the dma_pgprot() function and 
have TTM use it to set the pgprot for dma-coherent memory.

What do you think about this?

Thanks,

Thomas



                 reply	other threads:[~2020-03-16 15:24 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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=3d2317cd-bc40-47cb-3dae-8caa80acd767@shipmail.org \
    --to=thomas_os@shipmail.org \
    --cc=deathsimple@vodafone.de \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=hch@infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    /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
all inboxes | Powered by JetHome®