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[RFC 00/10] vDPA shadow virtqueue - notifications forwarding
From: |
Eugenio Pérez |
Subject: |
[RFC 00/10] vDPA shadow virtqueue - notifications forwarding |
Date: |
Fri, 29 Jan 2021 21:54:05 +0100 |
This series enable vhost (And vhost-vdpa) notifications forwarding for
software assisted live migration, implemented through a shadow
virtqueue.
Shadow virtqueue is a new method of tracking memory for migration:
Instead of relay on vDPA device's dirty logging capability, SW assisted
LM intercepts dataplane, forwarding the descriptors between VM and
device.
In this migration mode, qemu offers a new (shadow) vring to the device
to read and write into, and forwards descriptors between host vring
and qemu one. On used buffer relay, qemu will mark the dirty memory as
with plain virtio-net devices. This way, devices does not need to have
dirty page logging capability.
This RFC series just enables just the notifications forwarding part,
not buffer forwarding/tracking.
It is based on the ideas of DPDK SW assisted LM, in the series of
DPDK's https://patchwork.dpdk.org/cover/48370/ , but will use memory in
qemu Virtual Address Space for rings, instead of in guest's.
Main changes from previous RFC [1] are:
* Use QMP to enable. Can disable through QMP too.
* Do not use vhost_dev_{enable,disable}_notifiers, since they override
the VM ioeventfd set, and could cause race conditions. Do never modify
irqfd or ioeventfd used for the guest.
Comments are welcome.
Thanks!
[1] https://patchew.org/QEMU/20201120185105.279030-1-eperezma@redhat.com/
Eugenio Pérez (10):
virtio: Add virtqueue_set_handler
virtio: Add set_vq_handler
virtio: Add virtio_queue_get_idx
virtio: Add virtio_queue_host_notifier_status
vhost: Add vhost_dev_from_virtio
vhost: Save masked_notifier state
vhost: Add VhostShadowVirtqueue
vhost: Add x-vhost-enable-shadow-vq qmp
vhost: Route guest->host notification through shadow virtqueue
vhost: Route host->guest notification through shadow virtqueue
qapi/net.json | 23 +++
hw/virtio/vhost-shadow-virtqueue.h | 31 ++++
include/hw/virtio/vhost.h | 6 +
include/hw/virtio/virtio.h | 14 +-
hw/net/virtio-net.c | 26 ++++
hw/virtio/vhost-shadow-virtqueue.c | 234 +++++++++++++++++++++++++++++
hw/virtio/vhost.c | 161 ++++++++++++++++++++
hw/virtio/virtio.c | 24 +++
hw/virtio/meson.build | 2 +-
9 files changed, 517 insertions(+), 4 deletions(-)
create mode 100644 hw/virtio/vhost-shadow-virtqueue.h
create mode 100644 hw/virtio/vhost-shadow-virtqueue.c
--
2.27.0
- [RFC 00/10] vDPA shadow virtqueue - notifications forwarding,
Eugenio Pérez <=
- [RFC 01/10] virtio: Add virtqueue_set_handler, Eugenio Pérez, 2021/01/29
- [RFC 02/10] virtio: Add set_vq_handler, Eugenio Pérez, 2021/01/29
- [RFC 03/10] virtio: Add virtio_queue_get_idx, Eugenio Pérez, 2021/01/29
- [RFC 04/10] virtio: Add virtio_queue_host_notifier_status, Eugenio Pérez, 2021/01/29
- [RFC 05/10] vhost: Add vhost_dev_from_virtio, Eugenio Pérez, 2021/01/29
- [RFC 07/10] vhost: Add VhostShadowVirtqueue, Eugenio Pérez, 2021/01/29
- [RFC 06/10] vhost: Save masked_notifier state, Eugenio Pérez, 2021/01/29
- [RFC 08/10] vhost: Add x-vhost-enable-shadow-vq qmp, Eugenio Pérez, 2021/01/29
- [RFC 10/10] vhost: Route host->guest notification through shadow virtqueue, Eugenio Pérez, 2021/01/29
- [RFC 09/10] vhost: Route guest->host notification through shadow virtqueue, Eugenio Pérez, 2021/01/29