On Tue, Oct 12, 2021 at 11:59 AM Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > 在 2021/10/1 下午3:05, Eugenio Pérez 写道: > > This series enable shadow virtqueue (SVQ) for vhost-vdpa devices. This > > is intended as a new method of tracking the memory the devices touch > > during a migration process: Instead of relay on vhost device's dirty > > logging capability, SVQ intercepts the VQ dataplane forwarding the > > descriptors between VM and device. This way qemu is the effective > > writer of guests memory, like in qemu's virtio device operation. > > > > When SVQ is enabled qemu offers a new vring to the device to read > > and write into, and also intercepts kicks and calls between the device > > and the guest. Used buffers relay would cause dirty memory being > > tracked, but at this RFC SVQ is not enabled on migration automatically. > > > > It is based on the ideas of DPDK SW assisted LM, in the series of > > DPDK's https://patchwork.dpdk.org/cover/48370/ . However, these does > > not map the shadow vq in guest's VA, but in qemu's. > > > > For qemu to use shadow virtqueues the guest virtio driver must not use > > features like event_idx or indirect descriptors. These limitations will > > be addressed in later series, but they are left out for simplicity at > > the moment. > > > > SVQ needs to be enabled with QMP command: > > > > { "execute": "x-vhost-enable-shadow-vq", > > "arguments": { "name": "dev0", "enable": true } } > > > > This series includes some patches to delete in the final version that > > helps with its testing. The first two of the series freely implements > > the feature to stop the device and be able to retrieve its status. It's > > intended to be used with vp_vpda driver in a nested environment. This > > driver also need modifications to forward the new status bit. > > > > Patches 2-8 prepares the SVQ and QMP command to support guest to host > > notifications forwarding. If the SVQ is enabled with these ones > > applied and the device supports it, that part can be tested in > > isolation (for example, with networking), hopping through SVQ. > > > > Same thing is true with patches 9-13, but with device to guest > > notifications. > > > > The rest of the patches implements the actual buffer forwarding. > > > > Comments are welcome. > > > Hi Eugenio: > > > It would be helpful to have a public git repo for us to ease the review. > > Thanks > Btw, we also need to measure the performance impact of the shadow virtqueue. Thanks _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
