On Thu, Oct 17, 2019 at 09:42:53AM +0800, Jason Wang wrote: > > On 2019/10/15 下午10:37, Stefan Hajnoczi wrote: > > On Tue, Oct 15, 2019 at 11:37:17AM +0800, Jason Wang wrote: > > > On 2019/10/15 上午1:49, Stefan Hajnoczi wrote: > > > > On Fri, Oct 11, 2019 at 04:15:50PM +0800, Jason Wang wrote: > > > > > There are hardware that can do virtio datapath offloading while having > > > > > its own control path. This path tries to implement a mdev based > > > > > unified API to support using kernel virtio driver to drive those > > > > > devices. This is done by introducing a new mdev transport for virtio > > > > > (virtio_mdev) and register itself as a new kind of mdev driver. Then > > > > > it provides a unified way for kernel virtio driver to talk with mdev > > > > > device implementation. > > > > > > > > > > Though the series only contains kernel driver support, the goal is to > > > > > make the transport generic enough to support userspace drivers. This > > > > > means vhost-mdev[1] could be built on top as well by resuing the > > > > > transport. > > > > > > > > > > A sample driver is also implemented which simulate a virito-net > > > > > loopback ethernet device on top of vringh + workqueue. This could be > > > > > used as a reference implementation for real hardware driver. > > > > > > > > > > Consider mdev framework only support VFIO device and driver right now, > > > > > this series also extend it to support other types. This is done > > > > > through introducing class id to the device and pairing it with > > > > > id_talbe claimed by the driver. On top, this seris also decouple > > > > > device specific parents ops out of the common ones. > > > > I was curious so I took a quick look and posted comments. > > > > > > > > I guess this driver runs inside the guest since it registers virtio > > > > devices? > > > > > > It could run in either guest or host. But the main focus is to run in the > > > host then we can use virtio drivers in containers. > > > > > > > > > > If this is used with physical PCI devices that support datapath > > > > offloading then how are physical devices presented to the guest without > > > > SR-IOV? > > > > > > We will do control path meditation through vhost-mdev[1] and > > > vhost-vfio[2]. > > > Then we will present a full virtio compatible ethernet device for guest. > > > > > > SR-IOV is not a must, any mdev device that implements the API defined in > > > patch 5 can be used by this framework. > > What I'm trying to understand is: if you want to present a virtio-pci > > device to the guest (e.g. using vhost-mdev or vhost-vfio), then how is > > that related to this patch series? > > > This series introduce some infrastructure that would be used by vhost-mdev: > > 1) allow new type of mdev devices/drivers other than vfio (through class_id > and device ops) > > 2) a set of virtio specific callbacks that will be used by both vhost-mdev > and virtio-mdev defined in patch 5 > > Then vhost-mdev can be implemented on top: a new mdev class id but reuse the > callback defined in 2. Through this way the parent can provides a single set > of callbacks (device ops) for both kernel virtio driver (through > virtio-mdev) or userspace virtio driver (through vhost-mdev).
Okay, thanks for explaining! Stefan
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