Inter-VM device emulation (call on Mon 20th July 2020)

From: Stefan Hajnoczi <stefanha@redhat.com>
To: Nikos Dragazis <ndragazis@arrikto.com>,
	Jan Kiszka <jan.kiszka@siemens.com>
Cc: "John G. Johnson" <john.g.johnson@oracle.com>,
	"Andra-Irina Paraschiv" <andraprs@amazon.com>,
	kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org,
	"Maxime Coquelin" <maxime.coquelin@redhat.com>,
	"Alexander Graf" <graf@amazon.com>,
	"Thanos Makatos" <thanos.makatos@nutanix.com>,
	"Alex Bennée" <alex.bennee@linaro.org>
Subject: Inter-VM device emulation (call on Mon 20th July 2020)
Date: Wed, 15 Jul 2020 12:23:42 +0100	[thread overview]
Message-ID: <20200715112342.GD18817@stefanha-x1.localdomain> (raw)
In-Reply-To: <86d42090-f042-06a1-efba-d46d449df280@arrikto.com>

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Hi,
Several projects are underway to create an inter-VM device emulation
interface:

 * ivshmem v2
   https://www.mail-archive.com/qemu-devel@nongnu.org/msg706465.html

   A PCI device that provides shared-memory communication between VMs.
   This device already exists but is limited in its current form. The
   "v2" project updates IVSHMEM's capabilities and makes it suitable as
   a VIRTIO transport.

   Jan Kiszka is working on this and has posted specs for review.

 * virtio-vhost-user
   https://www.mail-archive.com/virtio-dev@lists.oasis-open.org/msg06429.html

   A VIRTIO device that transports the vhost-user protocol. Allows
   vhost-user device emulation to be implemented by another VM.

   Nikos Dragazis is working on this with QEMU, DPDK, and VIRTIO patches
   posted.

 * VFIO-over-socket
   https://github.com/tmakatos/qemu/blob/master/docs/devel/vfio-over-socket.rst

   Similar to the vhost-user protocol in spirit but for any PCI device.
   Uses the Linux VFIO ioctl API as the protocol instead of vhost.

   It doesn't have a virtio-vhost-user equivalent yet, but the same
   approach could be applied to VFIO-over-socket too.

   Thanos Makatos and John G. Johnson are working on this. The draft
   spec is available.

Let's have a call to figure out:

1. What is unique about these approaches and how do they overlap?
2. Can we focus development and code review efforts to get something
   merged sooner?

Jan and Nikos: do you have time to join on Monday, 20th of July at 15:00
UTC?
https://www.timeanddate.com/worldclock/fixedtime.html?iso=20200720T1500

Video call URL: https://bluejeans.com/240406010

It would be nice if Thanos and/or JJ could join the call too. Others
welcome too (feel free to forward this email)!

Stefan

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