[Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest

[Thibaut Collet]

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 <address@hidden>
---
 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.
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