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
>
