All of lore.kernel.org
 help / color / mirror / Atom feed
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Woodhouse <dwmw2@infradead.org>,
	Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	linux-arch <linux-arch@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	Sebastian Ott <sebott@linux.vnet.ibm.com>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Joerg Roedel <jroedel@suse.de>, Jonathan Corbet <corbet@lwn.net>,
	KVM <kvm@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v1 2/2] dma-mapping-common: add DMA attribute - DMA_ATTR_IOMMU_BYPASS
Date: Tue, 03 Nov 2015 10:10:13 +1100	[thread overview]
Message-ID: <1446505813.17404.23.camel@kernel.crashing.org> (raw)
In-Reply-To: <1446504494.15061.66.camel@infradead.org>

On Mon, 2015-11-02 at 22:48 +0000, David Woodhouse wrote:
> 
> In the Intel case, the mapping setup is entirely per-device (except for
> crap devices and devices behind a PCIe-PCI bridge, etc.).
> 
> So you can happily have a passthrough mapping for *one* device, without
> making that same mapping available to another device. You can make that
> trade-off of speed vs. protection for each device in the system.

Same for me. I should have written "in the context of a device ...",
the problem reamains that it doesn't buy you much to do it *per
-mapping* which is what this API seems to be about.

> Currently we have the 'iommu=pt' option that makes us use passthrough
> for *all* devices (except those whose dma_mask can't reach all of
> physical memory). But I could live with something like Shamir is
> proposing, which lets us do the bypass only for performance-sensitive
> devices which actually *ask* for it (and of course we'd have a system-
> wide mode which declines that request and does normal mappings anyway).
> 

  reply	other threads:[~2015-11-02 23:10 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-25 16:07 [PATCH v1 1/2] dma-mapping-common: add dma_map_page_attrs API Shamir Rabinovitch
2015-10-25 16:07 ` [PATCH v1 2/2] dma-mapping-common: add DMA attribute - DMA_ATTR_IOMMU_BYPASS Shamir Rabinovitch
2015-10-28  6:30   ` David Woodhouse
2015-10-28 11:10     ` Shamir Rabinovitch
2015-10-28 13:31       ` David Woodhouse
2015-10-28 14:07         ` David Miller
2015-10-28 13:57           ` David Woodhouse
2015-10-29  0:23             ` David Miller
2015-10-29  0:32         ` Benjamin Herrenschmidt
2015-10-29  0:42           ` David Woodhouse
2015-10-29  1:10             ` Benjamin Herrenschmidt
2015-10-29 18:31               ` Andy Lutomirski
2015-10-29 22:35                 ` David Woodhouse
2015-11-01  7:45                   ` Shamir Rabinovitch
2015-11-01 21:10                     ` Benjamin Herrenschmidt
2015-11-02  7:23                       ` Shamir Rabinovitch
2015-11-02 10:00                         ` Benjamin Herrenschmidt
2015-11-02 12:07                           ` Shamir Rabinovitch
2015-11-02 20:13                             ` Benjamin Herrenschmidt
2015-11-02 21:45                               ` Arnd Bergmann
2015-11-02 23:08                                 ` Benjamin Herrenschmidt
2015-11-03 13:11                                   ` Christoph Hellwig
2015-11-03 19:35                                     ` Benjamin Herrenschmidt
2015-11-02 21:49                               ` Shamir Rabinovitch
2015-11-02 22:48                       ` David Woodhouse
2015-11-02 23:10                         ` Benjamin Herrenschmidt [this message]
2015-11-05 21:08                   ` David Miller
2015-10-30  1:51                 ` Benjamin Herrenschmidt
2015-10-30 10:32               ` Arnd Bergmann
2015-10-30 23:17                 ` Benjamin Herrenschmidt
2015-10-30 23:24                   ` Arnd Bergmann
2015-11-02 14:51                 ` Joerg Roedel
2015-10-29  7:32             ` Shamir Rabinovitch
2015-11-02 14:44               ` Joerg Roedel
2015-11-02 17:32                 ` Shamir Rabinovitch
2015-11-05 13:42                   ` Joerg Roedel
2015-11-05 21:11                     ` David Miller
2015-11-07 15:06                       ` Shamir Rabinovitch
     [not found]                         ` <CAN+hb0UvztgwNuAh93XdJEe7vgiZgNMc9mHNziHpEopg8Oi4Mg@mail.gmail.com>
2015-11-16  8:42                           ` David Woodhouse
     [not found]                             ` <CAN+hb0UWpfcS5DvgMxNjY-5JOztw2mO1r2FJAW17fn974mhxPA@mail.gmail.com>
2015-11-16 18:42                               ` Benjamin Serebrin
2015-10-25 16:37 [PATCH v1 1/2] dma-mapping-common: add dma_map_page_attrs API Shamir Rabinovitch
2015-10-25 16:37 ` [PATCH v1 2/2] dma-mapping-common: add DMA attribute - DMA_ATTR_IOMMU_BYPASS Shamir Rabinovitch
2015-11-16  6:56 Benjamin Serebrin

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=1446505813.17404.23.camel@kernel.crashing.org \
    --to=benh@kernel.crashing.org \
    --cc=arnd@arndb.de \
    --cc=borntraeger@de.ibm.com \
    --cc=corbet@lwn.net \
    --cc=cornelia.huck@de.ibm.com \
    --cc=dwmw2@infradead.org \
    --cc=hch@lst.de \
    --cc=jroedel@suse.de \
    --cc=kvm@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=pbonzini@redhat.com \
    --cc=schwidefsky@de.ibm.com \
    --cc=sebott@linux.vnet.ibm.com \
    --cc=shamir.rabinovitch@oracle.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.