iommu.lists.linux-foundation.org archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	linux-mips@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 09/12] dma-direct: remove __dma_to_phys
Date: Fri, 11 Sep 2020 09:14:29 +0200	[thread overview]
Message-ID: <20200911071429.GE22394@lst.de> (raw)
In-Reply-To: <5d797c06-401d-62b1-f144-ea6e9a5144dd@arm.com>

On Thu, Sep 10, 2020 at 02:26:03PM +0100, Robin Murphy wrote:
> On 2020-09-08 17:47, Christoph Hellwig wrote:
>> There is no harm in just always clearing the SME encryption bit, while
>> significantly simplifying the interface.
>
> After a 10-minute diversion into "but hang on, force_dma_unencrypted() is 
> meaningful on PPC and S390 too..." before realising that it all does just 
> come back to __sme_clr(), which is indeed a no-op for everyone other than 
> AMD, any simplification of this mess is indeed welcome :)
>
> Unless I've massively misunderstood how SME is supposed to work,

Exactly.  This weird encryption bit in AMD SME causes all kinds of harm,
and I'm glad no one picked it up.  I've also been wondering if we
should change the interface to explicit set/clear the bit, but I'll
leave that for another pass as fixing up the SME interfaces would turn
into a massive disgression.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2020-09-11  7:14 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-08 16:47 dma-mapping cleanups Christoph Hellwig
2020-09-08 16:47 ` [PATCH 01/12] MIPS: make dma_sync_*_for_cpu a little less overzealous Christoph Hellwig
2020-09-08 16:47 ` [PATCH 02/12] MIPS/jazzdma: remove the unused vdma_remap function Christoph Hellwig
2020-09-08 16:47 ` [PATCH 03/12] MIPS/jazzdma: decouple from dma-direct Christoph Hellwig
2020-09-08 16:47 ` [PATCH 04/12] dma-mapping: fix DMA_OPS dependencies Christoph Hellwig
2020-09-08 18:04   ` Sergei Shtylyov
2020-09-11  7:10     ` Christoph Hellwig
2020-09-10 12:55   ` Robin Murphy
2020-09-11  7:09     ` Christoph Hellwig
2020-09-08 16:47 ` [PATCH 05/12] dma-mapping: add (back) arch_dma_mark_clean for ia64 Christoph Hellwig
2020-09-08 16:47 ` [PATCH 06/12] dma-direct: remove dma_direct_{alloc,free}_pages Christoph Hellwig
2020-09-10 12:57   ` Robin Murphy
2020-09-08 16:47 ` [PATCH 07/12] dma-direct: lift gfp_t manipulation out of__dma_direct_alloc_pages Christoph Hellwig
2020-09-10 13:02   ` Robin Murphy
2020-09-08 16:47 ` [PATCH 08/12] dma-direct: use phys_to_dma_direct in dma_direct_alloc Christoph Hellwig
2020-09-10 13:03   ` Robin Murphy
2020-09-08 16:47 ` [PATCH 09/12] dma-direct: remove __dma_to_phys Christoph Hellwig
2020-09-10 13:26   ` Robin Murphy
2020-09-11  7:14     ` Christoph Hellwig [this message]
2020-09-08 16:47 ` [PATCH 10/12] dma-direct: rename and cleanup __phys_to_dma Christoph Hellwig
2020-09-10 13:30   ` Robin Murphy
2020-09-08 16:47 ` [PATCH 11/12] dma-mapping: move dma_common_{mmap, get_sgtable} out of mapping.c Christoph Hellwig
2020-09-10 13:34   ` Robin Murphy
2020-09-11  7:15     ` [PATCH 11/12] dma-mapping: move dma_common_{mmap,get_sgtable} " Christoph Hellwig
2020-09-08 16:47 ` [PATCH 12/12] dma-mapping: move the dma_declare_coherent_memory documentation Christoph Hellwig
2020-09-10 13:51   ` Robin Murphy
2020-09-11  7:17     ` 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=20200911071429.GE22394@lst.de \
    --to=hch@lst.de \
    --cc=fenghua.yu@intel.com \
    --cc=iommu@lists.linux-foundation.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=tony.luck@intel.com \
    --cc=tsbogend@alpha.franken.de \
    --subject='Re: [PATCH 09/12] dma-direct: remove __dma_to_phys' \
    /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

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).