From: Alex Williamson <alex.williamson@redhat.com>
To: Vincent JARDIN <vincent.jardin@6wind.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] VFIO no-iommu
Date: Fri, 11 Dec 2015 16:02:33 -0700 [thread overview]
Message-ID: <1449874953.20509.6.camel@redhat.com> (raw)
In-Reply-To: <566B4A50.9090607@6wind.com>
On Fri, 2015-12-11 at 23:12 +0100, Vincent JARDIN wrote:
> Thanks Thomas for putting back this topic.
>
> Alex,
>
> I'd like to hear more about the impacts of "unsupported":
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commi
> t/?id=033291eccbdb1b70ffc02641edae19ac825dc75d
> Use of this mode, specifically binding a device without a native
> IOMMU group to a VFIO bus driver will taint the kernel and should
> therefore not be considered supported.
>
> It means that we get ride of uio; so it is a nice code cleanup: but
> why
> would VFIO/NO IOMMU be better if the bottomline is "unsupported"?
How supportable do you think the uio method is? Fundamentally we have
a userspace driver doing unrestricted DMA; it can access and modify any
memory in the system. This is the reason uio won't provide a mechanism
to enable MSI and if you ask the uio maintainer, they don't support DMA
at all, it's only intended as a programmed IO interface to the device.
Unless we can sandbox a user owned device within an IOMMU protected
container, it's not supportable. The VFIO no-iommu mode can simply
provide you that unsupported mode more easily since it leverages code
from the supported mode, which is IOMMU protected. Thanks,
Alex
next prev parent reply other threads:[~2015-12-11 23:02 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-11 16:28 Thomas Monjalon
2015-12-11 22:12 ` Vincent JARDIN
2015-12-11 23:02 ` Alex Williamson [this message]
2015-12-15 13:43 ` O'Driscoll, Tim
2015-12-15 16:53 ` Alex Williamson
2015-12-16 4:04 ` Ferruh Yigit
2015-12-16 4:38 ` Alex Williamson
2015-12-16 8:35 ` Burakov, Anatoly
2015-12-16 16:23 ` Burakov, Anatoly
2015-12-16 23:17 ` Thomas Monjalon
2015-12-17 9:52 ` Burakov, Anatoly
2015-12-17 10:09 ` Thomas Monjalon
2015-12-17 19:38 ` Jan Viktorin
2015-12-17 21:16 ` Vincent JARDIN
2015-12-17 23:29 ` Stephen Hemminger
2015-12-16 17:11 ` Alex Williamson
2015-12-16 17:22 ` Burakov, Anatoly
2015-12-17 16:43 ` Alex Williamson
2015-12-18 10:43 ` Yigit, Ferruh
2015-12-18 14:38 ` Alex Williamson
2015-12-18 21:50 ` Alex Williamson
2015-12-21 11:46 ` Yigit, Ferruh
2015-12-21 12:18 ` [dpdk-dev] [PATCH] vfio: add no-iommu support Ferruh Yigit
2015-12-21 15:15 ` Burakov, Anatoly
2015-12-21 15:26 ` Yigit, Ferruh
2015-12-21 15:28 ` Burakov, Anatoly
2015-12-21 19:22 ` [dpdk-dev] VFIO no-iommu Alex Williamson
2015-12-22 20:20 ` Alex Williamson
2015-12-23 11:19 ` Burakov, Anatoly
2015-12-31 14:30 ` Santosh Shukla
2016-01-14 6:03 ` Jike Song
2016-01-14 6:52 ` Alex Williamson
2016-01-14 8:12 ` Jike Song
2015-12-11 23:20 ` Jan Viktorin
2015-12-15 11:20 ` Alejandro Lucero
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