14/08/2020 21:16, Chenbo Xia:
> Background & Motivation
> -----------------------
> In order to reduce the attack surface, QEMU community is disaggregating QEMU
> by
> removing part of device emulation from it. The disaggregated/multi-process
> QEMU
> is using VFIO-over-socket/vfio-user as the main transport mechanism to
> disaggregate
> I/O services from QEMU[2]. Vfio-user essentially implements the VFIO device
> model
> presented to the user process by a set of messages over a unix-domain socket.
> The
> main difference between application using vfio-user and application using vfio
> kernel module is that device manipulation is based on socket messages for
> vfio-user
> but system calls for vfio kernel module. The vfio-user devices consist of a
> generic
> VFIO device type, living in QEMU, which is called the client[3], and the core
> device
> implementation (emulated device), living outside of QEMU, which is called the
> server.
>
> With the introduction and support of vfio-user in QEMU, QEMU is explicitly
> adding
> support for external emulated device and data path. We are trying to leverage
> that
> and introducing vfio-user support in DPDK. By doing so, DPDK is enabled to be
> an
> alternative I/O device emulation library of building virtualized devices
> along with
> high-performance data path in separate processes outside QEMU. It will be
> easy for
> hardware vendors to provide virtualized solutions of their hardware devices by
> implementing emulated device in DPDK.
>
> Except for vfio-user introduced in DPDK, this series also introduces the first
> emulated device implementation. That is emulated AVF device (avf_emudev)
> implemented
> by AVF emulation driver (avf_emudev driver). Emulated AVF device demos how
> emulated
> device could be implemented in DPDK. SPDK is also investigating to implement
> use case
> for NVMe.
I am completely unaware of this change in QEMU.
I've found this presentation about Multi-process QEMU by Oracle:
https://static.sched.com/hosted_files/kvmforum2019/d2/kvm-mpqemu.pdf
and there is the wiki page you already referenced:
https://wiki.qemu.org/Features/MultiProcessQEMU
I guess virtio stays inside QEMU?
What is really moving out? e1000, ne2000 and vmxnet3?
Why emulated AVF is needed, compared to a simple VFIO passthrough?
