From: David Woodhouse <dwmw2@infradead.org>
To: "Michael S. Tsirkin" <mst@redhat.com>, Joerg Roedel <joro@8bytes.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Wei Liu <wei.liu2@citrix.com>,
Andy Lutomirski <luto@kernel.org>,
qemu-block@nongnu.org,
Christian Borntraeger <borntraeger@de.ibm.com>,
Jason Wang <jasowang@redhat.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
qemu-devel@nongnu.org, peterx@redhat.com,
linux-kernel@vger.kernel.org, Amit Shah <amit.shah@redhat.com>,
iommu@lists.linux-foundation.org,
Stefan Hajnoczi <stefanha@redhat.com>,
kvm@vger.kernel.org, cornelia.huck@de.ibm.com,
pbonzini@redhat.com, virtualization@lists.linux-foundation.org,
Anthony PERARD <anthony.perard@citrix.com>
Subject: Re: [PATCH V2 RFC] fixup! virtio: convert to use DMA api
Date: Wed, 27 Apr 2016 16:15:35 +0100 [thread overview]
Message-ID: <1461770135.118304.152.camel@infradead.org> (raw)
In-Reply-To: <20160427180007-mutt-send-email-mst@redhat.com>
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On Wed, 2016-04-27 at 18:05 +0300, Michael S. Tsirkin wrote:
>
> I really don't get it.
>
> There's exactly one device that works now and needs the work-around and
> so that we need to support, and that is virtio. It happens to have
> exactly the same issue on all platforms.
False. We have other devices which are currently *not* translated by
the emulated IOMMU and which aren't going to be in the short term
either.
We also have other devices (emulated hardware NICs) to which precisely
the same "we don't need protection" arguments apply, and which we
*could* expose to the guest without an IOMMU translation if we really
wanted to. It makes as much sense as exposing virtio without an IOMMU,
going forward.
> Why would we want to work hard to build platform-specific
> solutions to a problem that can be solved in 5 lines of
> generic code?
Because it's a dirty hack in the *wrong* place.
--
dwmw2
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next prev parent reply other threads:[~2016-04-27 15:15 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 13:43 [PATCH V2 RFC] fixup! virtio: convert to use DMA api Michael S. Tsirkin
2016-04-21 13:54 ` Wei Liu
2016-04-27 12:18 ` David Woodhouse
2016-04-27 13:37 ` Michael S. Tsirkin
2016-04-27 14:23 ` Joerg Roedel
2016-04-27 14:31 ` Andy Lutomirski
2016-04-27 14:38 ` Michael S. Tsirkin
2016-04-27 14:43 ` Andy Lutomirski
2016-04-27 14:54 ` Michael S. Tsirkin
2016-04-27 14:58 ` Joerg Roedel
2016-04-27 15:09 ` Michael S. Tsirkin
2016-04-27 15:10 ` Andy Lutomirski
2016-04-27 14:34 ` Michael S. Tsirkin
2016-04-27 14:56 ` Joerg Roedel
2016-04-27 15:05 ` Michael S. Tsirkin
2016-04-27 15:15 ` David Woodhouse [this message]
2016-04-27 18:17 ` Michael S. Tsirkin
2016-04-27 19:16 ` David Woodhouse
2016-04-28 14:34 ` Michael S. Tsirkin
2016-04-28 15:11 ` David Woodhouse
2016-04-28 15:37 ` Michael S. Tsirkin
2016-04-28 15:48 ` David Woodhouse
2016-05-01 10:37 ` Michael S. Tsirkin
2016-05-09 11:09 ` Paolo Bonzini
2016-04-21 14:56 ` Stefan Hajnoczi
2016-04-21 15:11 ` Michael S. Tsirkin
2016-04-22 9:33 ` Stefan Hajnoczi
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