From: Paolo Bonzini <pbonzini@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
liu ping fan <qemulist@gmail.com>,
Anthony Liguori <anthony@codemonkey.ws>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [big lock] Discussion about the convention of device's DMA each other after breaking down biglock
Date: Thu, 27 Sep 2012 12:22:41 +0200 [thread overview]
Message-ID: <506428F1.6090004@redhat.com> (raw)
In-Reply-To: <506425B8.1040706@redhat.com>
Il 27/09/2012 12:08, Avi Kivity ha scritto:
>>>>> virtio-net is per-spec not going through the iommu.
>>> >> What's that smell? A feature bit?
>> >
>> > Why is it a bad thing that it does not go through the iommu?
> You can't assign the device to nested guests or to guest userspace via
> vfio. Some guests may want to use the iommu even in the guest kernel
> context.
All good points.
However, using the iommu means you cannot use either vhost-net or (at
least for now) per-device lock. So it closes some doors on performance
improvements... I can imagine pSeries guys prefer to keep no iommu in
virtio devices.
Paolo
next prev parent reply other threads:[~2012-09-27 10:22 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-19 3:02 [Qemu-devel] [big lock] Discussion about the convention of device's DMA each other after breaking down biglock liu ping fan
2012-09-19 8:06 ` Avi Kivity
2012-09-19 9:00 ` liu ping fan
2012-09-19 9:07 ` Avi Kivity
2012-09-19 9:11 ` liu ping fan
2012-09-19 9:14 ` Paolo Bonzini
2012-09-19 9:19 ` liu ping fan
2012-09-19 9:23 ` Avi Kivity
2012-09-19 9:27 ` Jan Kiszka
2012-09-19 9:28 ` Jan Kiszka
2012-09-20 7:51 ` liu ping fan
2012-09-20 7:54 ` Paolo Bonzini
2012-09-20 8:09 ` liu ping fan
2012-09-20 8:27 ` Paolo Bonzini
2012-09-20 9:07 ` Avi Kivity
2012-09-21 7:27 ` liu ping fan
2012-09-21 8:21 ` Paolo Bonzini
2012-09-19 9:21 ` Avi Kivity
2012-09-19 9:51 ` Paolo Bonzini
2012-09-19 10:06 ` Avi Kivity
2012-09-19 10:19 ` Paolo Bonzini
2012-09-19 10:27 ` Avi Kivity
2012-09-19 9:34 ` Jan Kiszka
2012-09-19 9:50 ` Avi Kivity
2012-09-19 10:18 ` Jan Kiszka
2012-09-24 6:33 ` liu ping fan
2012-09-24 7:44 ` Avi Kivity
2012-09-24 8:32 ` liu ping fan
2012-09-24 9:42 ` Avi Kivity
2012-09-27 3:13 ` liu ping fan
2012-09-27 9:16 ` Avi Kivity
2012-09-27 9:29 ` Paolo Bonzini
2012-09-27 9:34 ` Avi Kivity
2012-09-27 9:36 ` Paolo Bonzini
2012-09-27 10:08 ` Avi Kivity
2012-09-27 10:22 ` Paolo Bonzini [this message]
2012-09-27 10:48 ` Avi Kivity
2012-09-29 9:20 ` liu ping fan
2012-09-30 8:13 ` Avi Kivity
2012-09-30 8:48 ` liu ping fan
2012-09-30 11:18 ` Avi Kivity
2012-09-30 11:04 ` Blue Swirl
2012-09-30 11:17 ` Avi Kivity
2012-09-30 11:48 ` Blue Swirl
2012-09-20 8:11 ` liu ping fan
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