Register a new vmstate for virtio-net with an early_setup flag to send
the device state during migration setup.
This can reduce the migration downtime of a virtio-net device with a
vhost-user backend.
This feature is disabled by default and can be enabled by setting the
"x-early-migration" device property to on.
Signed-off-by: Yajun Wu <yajunw@nvidia.com>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
---
hw/net/trace-events | 1 +
hw/net/virtio-net.c | 100 +++++++++++++++++++++++++++++++++
include/hw/virtio/virtio-net.h | 1 +
3 files changed, 102 insertions(+)
diff --git a/hw/net/trace-events b/hw/net/trace-events
index 6b5ba669a2..ec89229044 100644
--- a/hw/net/trace-events
+++ b/hw/net/trace-events
@@ -399,6 +399,7 @@ virtio_net_post_load_device(void)
virtio_net_rss_disable(void)
virtio_net_rss_error(const char *msg, uint32_t value) "%s, value 0x%08x"
virtio_net_rss_enable(uint32_t p1, uint16_t p2, uint8_t p3) "hashes 0x%x, table of %d, key of %d"
+virtio_net_load_early_setup(void) ""
# tulip.c
tulip_reg_write(uint64_t addr, const char *name, int size, uint64_t val) "addr 0x%02"PRIx64" (%s) size %d value 0x%08"PRIx64
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 7102ec4817..d0b0cc2ffe 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -46,6 +46,7 @@
#include "net_rx_pkt.h"
#include "hw/virtio/vhost.h"
#include "sysemu/qtest.h"
+#include "sysemu/runstate.h"
#define VIRTIO_NET_VM_VERSION 11
@@ -3568,6 +3569,95 @@ static bool failover_hide_primary_device(DeviceListener *listener,
return qatomic_read(&n->failover_primary_hidden);
}
+static int virtio_net_load_early_setup(void *opaque, int version_id)
+{
+ VirtIONet *n = opaque;
+ VirtIODevice *vdev = VIRTIO_DEVICE(n);
+ NetClientState *nc = qemu_get_queue(n->nic);
+ int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
+ int cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
+ n->max_ncs - n->max_queue_pairs : 0;
+ VHostNetState *net;
+ int r;
+
+ assert(nc->peer);
+ assert(nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER);
+
+ net = get_vhost_net(nc->peer);
+ assert(net);
+ assert(net->dev.vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+
+ trace_virtio_net_load_early_setup();
+
+ /* backend should support presetup */
+ r = vhost_dev_set_presetup_state(&net->dev, true);
+ if (r < 0) {
+ error_report("Start presetup device fail: %d", r);
+ return r;
+ }
+
+ if (virtio_has_feature(vdev->guest_features, VIRTIO_NET_F_MTU)) {
+ r = vhost_net_set_mtu(get_vhost_net(nc->peer), n->net_conf.mtu);
+ if (r < 0) {
+ error_report("%uBytes MTU not supported by the backend",
+ n->net_conf.mtu);
+ goto error;
+ }
+ }
+
+ r = vhost_net_presetup(vdev, n->nic->ncs, queue_pairs, cvq);
+ if (r < 0) {
+ error_report("Presetup device fail: %d", r);
+ goto error;
+ }
+
+ r = vhost_dev_set_presetup_state(&net->dev, false);
+ if (r < 0) {
+ error_report("Finish presetup device fail: %d", r);
+ return r;
+ }
+ return 0;
+
+error:
+ vhost_dev_set_presetup_state(&net->dev, false);
+ return r;
+}
+
+static bool virtio_net_early_setup_needed(void *opaque)
+{
+ VirtIONet *n = opaque;
+ NetClientState *nc = qemu_get_queue(n->nic);
+ VHostNetState *net = get_vhost_net(nc->peer);
+
+ /*
+ * Presetup aims to reduce live migration downtime by sync device
+ * status in setup stage. So only do presetup when source VM is in
+ * running state.
+ */
+ if (runstate_is_running() &&
+ nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER &&
+ net->dev.vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER &&
+ !vhost_dev_has_iommu(&net->dev) &&
+ n->vhost_started &&
+ n->status & VIRTIO_NET_S_LINK_UP) {
+ return true;
+ }
+ return false;
+}
+
+static const VMStateDescription vmstate_virtio_net_early = {
+ .name = "virtio-net-early",
+ .minimum_version_id = VIRTIO_NET_VM_VERSION,
+ .version_id = VIRTIO_NET_VM_VERSION,
+ .fields = (VMStateField[]) {
+ VMSTATE_EARLY_VIRTIO_DEVICE,
+ VMSTATE_END_OF_LIST()
+ },
+ .early_setup = true,
+ .post_load = virtio_net_load_early_setup,
+ .needed = virtio_net_early_setup_needed,
+};
+
static void virtio_net_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
@@ -3743,6 +3833,11 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) {
virtio_net_load_ebpf(n);
}
+
+ if (n->early_migration) {
+ vmstate_register(NULL, VMSTATE_INSTANCE_ID_ANY,
+ &vmstate_virtio_net_early, n);
+ }
}
static void virtio_net_device_unrealize(DeviceState *dev)
@@ -3787,6 +3882,10 @@ static void virtio_net_device_unrealize(DeviceState *dev)
g_free(n->rss_data.indirections_table);
net_rx_pkt_uninit(n->rx_pkt);
virtio_cleanup(vdev);
+
+ if (n->early_migration) {
+ vmstate_unregister(NULL, &vmstate_virtio_net_early, n);
+ }
}
static void virtio_net_instance_init(Object *obj)
@@ -3922,6 +4021,7 @@ static Property virtio_net_properties[] = {
DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
DEFINE_PROP_BOOL("failover", VirtIONet, failover, false),
+ DEFINE_PROP_BOOL("x-early-migration", VirtIONet, early_migration, false),
DEFINE_PROP_END_OF_LIST(),
};
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index e07a723027..9e6f90b46f 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -212,6 +212,7 @@ struct VirtIONet {
/* primary failover device is hidden*/
bool failover_primary_hidden;
bool failover;
+ bool early_migration;
DeviceListener primary_listener;
QDict *primary_opts;
bool primary_opts_from_json;
--
2.27.0
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