From: Christoph Hellwig <hch@infradead.org>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Christoph Hellwig <hch@infradead.org>, linuxppc-dev@lists.ozlabs.org
Subject: Re: question on "powerpc/pseries/dma: Allow SWIOTLB"
Date: Fri, 19 Jul 2019 01:05:32 -0700 [thread overview]
Message-ID: <20190719080532.GA3861@infradead.org> (raw)
In-Reply-To: <33ba562c-1a87-58e2-4105-520834d5b969@ozlabs.ru>
On Fri, Jul 19, 2019 at 06:00:25PM +1000, Alexey Kardashevskiy wrote:
> > But shouldn't we force usage of the direct ops in that case as the
> > IOMMU is not neededed at all?
>
> We do, for mappings, but not unmappings and syncing.
Well, I mean as in literally not setting a dma_ops so that the
dma_direct code is used without the indirection through the iommu ops.
This is not only more obvious, but also faster as you avoid the
indirect call (although that probably doesn't matter much if you
are bounce buffering anyway).
> > Also isn't that support non-upstream so far?
>
> How is this relevant? I expect the existing "swiotlb=force" just work.
I though the whole secure VM support was still not upstream.
next prev parent reply other threads:[~2019-07-19 8:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 7:10 question on "powerpc/pseries/dma: Allow SWIOTLB" Christoph Hellwig
2019-07-19 7:52 ` Alexey Kardashevskiy
2019-07-19 7:53 ` Christoph Hellwig
2019-07-19 8:00 ` Alexey Kardashevskiy
2019-07-19 8:05 ` Christoph Hellwig [this message]
2019-07-19 8:23 ` Alexey Kardashevskiy
2019-07-19 12:25 ` Christoph Hellwig
2019-07-20 11:22 ` Alexey Kardashevskiy
2019-07-22 9:23 ` Christoph Hellwig
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=20190719080532.GA3861@infradead.org \
--to=hch@infradead.org \
--cc=aik@ozlabs.ru \
--cc=linuxppc-dev@lists.ozlabs.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;
as well as URLs for NNTP newsgroup(s).