From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: marcel@redhat.com, "Aviv B.D." <bd.aviv@gmail.com>,
Alex Williamson <alex.williamson@redhat.com>,
qemu-devel@nongnu.org, Peter Xu <peterx@redhat.com>
Subject: Re: [Qemu-devel] [PATCH][RFC] IOMMU: Add Support to VFIO devices with vIOMMU present
Date: Tue, 15 Mar 2016 09:00:17 +0200 [thread overview]
Message-ID: <20160315085849-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <56E709CF.1060109@siemens.com>
On Mon, Mar 14, 2016 at 07:58:23PM +0100, Jan Kiszka wrote:
> On 2016-03-14 19:52, Marcel Apfelbaum wrote:
> > On 03/12/2016 06:13 PM, Aviv B.D. wrote:
> >> From: "Aviv B.D." <bd.aviv@gmail.com <mailto:bd.aviv@gmail.com>>
> >>
> >> * Fix bug that prevent qemu from starting up when vIOMMU and VFIO
> >> device are present.
> >> * Advertise Cache Mode capability in iommu cap register.
>
> For the final version: Please keep that feature optional, for the sake
> of emulation accuracy (no modern hw exposes it any more). Maybe turn it
> one once a vfio device is in the scope of the IOMMU?
That would be hard to implement: VFIO supports hotplug and there's no way to
change this on the fly.
I would say
- make the feature an optional flag
- deny adding a VFIO device if the flag is not set
> >> * Register every VFIO device with IOMMU state.
> >> * On page cache invalidation in vIOMMU, check if the domain belong to
> >> VFIO device and mirror the guest requests to host.
> >>
> >> Not working (Yet!):
> >> * Tested only with network interface card (ixgbevf) and
> >> intel_iommu=strict in guest's kernel command line.
> >> * Lock up under high load.
> >> * Errors on guest poweroff.
> >> * High relative latency compare to VFIO without IOMMU.
> >
> > Adding (possibly) interested developers to the thread.
>
> Thanks,
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RDA ITP SES-DE
> Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2016-03-15 7:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-12 16:13 [Qemu-devel] [PATCH][RFC] IOMMU: Add Support to VFIO devices with vIOMMU present Aviv B.D.
2016-03-14 18:52 ` Marcel Apfelbaum
2016-03-14 18:58 ` Jan Kiszka
2016-03-15 7:00 ` Michael S. Tsirkin [this message]
2016-03-15 8:52 ` Peter Xu
2016-03-17 11:17 ` Aviv B.D.
2016-03-18 3:06 ` Peter Xu
2016-03-19 9:40 ` Aviv B.D.
2016-03-21 2:30 ` Peter Xu
2016-03-22 8:13 ` Aviv B.D.
2016-03-15 10:53 ` Michael S. Tsirkin
2016-03-17 11:58 ` Aviv B.D.
2016-03-23 14:34 ` Michael S. Tsirkin
2016-03-23 14:33 ` Michael S. Tsirkin
2016-03-26 14:47 ` Aviv B.D.
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