I have involved QEMU because QEMU prepares the rarp. I agree that backend has probably all the information to do that. But backend does not know if the guest supports the VIRTIO_NET_F_GUEST_ANNOUNCE and will send a useless rarp.
Maybe this duplication of requests is not very important and in this case this patch is not mandatory. On Wed, Jun 10, 2015 at 5:34 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > On Wed, Jun 10, 2015 at 03:43:03PM +0200, Thibaut Collet wrote: > > In case of live migration with legacy guest (without > VIRTIO_NET_F_GUEST_ANNOUNCE) > > a message is added between QEMU and the vhost client/backend. > > This message provides the RARP content, prepared by QEMU, to the vhost > > client/backend. > > The vhost client/backend is responsible to send the RARP. > > > > Signed-off-by: Thibaut Collet <thibaut.col...@6wind.com> > > --- > > docs/specs/vhost-user.txt | 16 ++++++++++++++++ > > hw/net/vhost_net.c | 8 ++++++++ > > hw/virtio/vhost-user.c | 11 ++++++++++- > > linux-headers/linux/vhost.h | 9 +++++++++ > > 4 files changed, 43 insertions(+), 1 deletion(-) > > > > diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > > index 2c8e934..ef5d475 100644 > > --- a/docs/specs/vhost-user.txt > > +++ b/docs/specs/vhost-user.txt > > @@ -97,6 +97,7 @@ typedef struct VhostUserMsg { > > uint64_t u64; > > struct vhost_vring_state state; > > struct vhost_vring_addr addr; > > + struct vhost_inject_rarp rarp; > > VhostUserMemory memory; > > }; > > } QEMU_PACKED VhostUserMsg; > > @@ -132,6 +133,12 @@ Multi queue support > > The protocol supports multiple queues by setting all index fields in > the sent > > messages to a properly calculated value. > > > > +Live migration support > > +---------------------- > > +The protocol supports live migration. GARP from the migrated guest is > done > > +through the VIRTIO_NET_F_GUEST_ANNOUNCE mechanism for guest that > supports it or > > +through RARP. > > + > > Message types > > ------------- > > > > @@ -269,3 +276,12 @@ Message types > > Bits (0-7) of the payload contain the vring index. Bit 8 is the > > invalid FD flag. This flag is set when there is no file descriptor > > in the ancillary data. > > + > > + * VHOST_USER_NET_INJECT_RARP > > + > > + Id: 15 > > + Master payload: rarp content > > + > > + Provide the RARP message to send to the guest after a live > migration. This > > + message is sent only for guest that does not support > > + VIRTIO_NET_F_GUEST_ANNOUNCE. > > I don't see why this is needed. > Can't backend simply send rarp itself? > Why do we need to involve QEMU? > > > > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > > index 4a42325..f66d48d 100644 > > --- a/hw/net/vhost_net.c > > +++ b/hw/net/vhost_net.c > > @@ -369,10 +369,18 @@ void vhost_net_stop(VirtIODevice *dev, > NetClientState *ncs, > > > > void vhost_net_inject_rarp(struct vhost_net *net, const uint8_t *buf, > size_t size) > > { > > + struct vhost_inject_rarp inject_rarp; > > + memcpy(&inject_rarp.rarp, buf, size); > > + > > if ((net->dev.acked_features & (1 << VIRTIO_NET_F_GUEST_ANNOUNCE)) > == 0) { > > + const VhostOps *vhost_ops = net->dev.vhost_ops; > > + int r; > > + > > fprintf(stderr, > > "Warning: Guest with no VIRTIO_NET_F_GUEST_ANNOUNCE > support. RARP must be sent by vhost-user backend\n"); > > fflush(stderr); > > + r = vhost_ops->vhost_call(&net->dev, VHOST_NET_INJECT_RARP, > &inject_rarp); > > + assert(r >= 0); > > } > > } > > > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > > index d6f2163..2e752ab 100644 > > --- a/hw/virtio/vhost-user.c > > +++ b/hw/virtio/vhost-user.c > > @@ -41,6 +41,7 @@ typedef enum VhostUserRequest { > > VHOST_USER_SET_VRING_KICK = 12, > > VHOST_USER_SET_VRING_CALL = 13, > > VHOST_USER_SET_VRING_ERR = 14, > > + VHOST_USER_NET_INJECT_RARP = 15, > > VHOST_USER_MAX > > } VhostUserRequest; > > > > @@ -70,6 +71,7 @@ typedef struct VhostUserMsg { > > uint64_t u64; > > struct vhost_vring_state state; > > struct vhost_vring_addr addr; > > + struct vhost_inject_rarp rarp; > > VhostUserMemory memory; > > }; > > } QEMU_PACKED VhostUserMsg; > > @@ -104,7 +106,8 @@ static unsigned long int > ioctl_to_vhost_user_request[VHOST_USER_MAX] = { > > VHOST_GET_VRING_BASE, /* VHOST_USER_GET_VRING_BASE */ > > VHOST_SET_VRING_KICK, /* VHOST_USER_SET_VRING_KICK */ > > VHOST_SET_VRING_CALL, /* VHOST_USER_SET_VRING_CALL */ > > - VHOST_SET_VRING_ERR /* VHOST_USER_SET_VRING_ERR */ > > + VHOST_SET_VRING_ERR, /* VHOST_USER_SET_VRING_ERR */ > > + VHOST_NET_INJECT_RARP /* VHOST_USER_NET_INJECT_RARP */ > > }; > > > > static VhostUserRequest vhost_user_request_translate(unsigned long int > request) > > @@ -287,6 +290,12 @@ static int vhost_user_call(struct vhost_dev *dev, > unsigned long int request, > > msg.u64 |= VHOST_USER_VRING_NOFD_MASK; > > } > > break; > > + > > + case VHOST_NET_INJECT_RARP: > > + memcpy(&msg.rarp, arg, sizeof(struct vhost_inject_rarp)); > > + msg.size = sizeof(struct vhost_inject_rarp); > > + break; > > + > > default: > > error_report("vhost-user trying to send unhandled ioctl"); > > return -1; > > diff --git a/linux-headers/linux/vhost.h b/linux-headers/linux/vhost.h > > index c656f61..1920134 100644 > > --- a/linux-headers/linux/vhost.h > > +++ b/linux-headers/linux/vhost.h > > @@ -63,6 +63,10 @@ struct vhost_memory { > > struct vhost_memory_region regions[0]; > > }; > > > > +struct vhost_inject_rarp { > > + __u8 rarp[60]; > > +}; > > + > > /* ioctls */ > > > > #define VHOST_VIRTIO 0xAF > > @@ -121,6 +125,11 @@ struct vhost_memory { > > * device. This can be used to stop the ring (e.g. for migration). */ > > #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct > vhost_vring_file) > > > > +/* Inject a RARP in case of live migration for guest that does not > support > > + * VIRTIO_NET_F_GUEST_ANNOUNCE */ > > +#define VHOST_NET_INJECT_RARP _IOW(VHOST_VIRTIO, 0x31, struct > vhost_inject_rarp) > > + > > + > > /* Feature bits */ > > /* Log all write descriptors. Can be changed while device is active. */ > > #define VHOST_F_LOG_ALL 26 > > -- > > 1.7.10.4 >