On 11/18/2016 03:26 PM, Aaron Conole wrote:
Maxime Coquelin <maxime.coque...@redhat.com> writes:This patch adds VHOST_USER_PROTOCOL_F_MTU protocol feature. If supported, QEMU sends VHOST_USER_GET_MTU request to the client, and expects a u64 reply containing the MTU advised for the guest. Cc: Michael S. Tsirkin <m...@redhat.com> Cc: Aaron Conole <acon...@redhat.com> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com> --- hw/virtio/vhost-user.c | 11 +++++++++++ include/hw/virtio/vhost.h | 1 + 2 files changed, 12 insertions(+) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 7ee92b3..eaf007d 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -32,6 +32,7 @@ enum VhostUserProtocolFeature { VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1, VHOST_USER_PROTOCOL_F_RARP = 2, VHOST_USER_PROTOCOL_F_REPLY_ACK = 3, + VHOST_USER_PROTOCOL_F_MTU = 4, VHOST_USER_PROTOCOL_F_MAX }; @@ -59,6 +60,7 @@ typedef enum VhostUserRequest { VHOST_USER_GET_QUEUE_NUM = 17, VHOST_USER_SET_VRING_ENABLE = 18, VHOST_USER_SEND_RARP = 19, + VHOST_USER_GET_MTU = 20, VHOST_USER_MAX } VhostUserRequest; @@ -186,6 +188,7 @@ static bool vhost_user_one_time_request(VhostUserRequest request) case VHOST_USER_RESET_OWNER: case VHOST_USER_SET_MEM_TABLE: case VHOST_USER_GET_QUEUE_NUM: + case VHOST_USER_GET_MTU: return true; default: return false; @@ -602,6 +605,14 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque) return err; } } + + /* query the MTU we support if backend supports MTU feature */ + if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MTU)) { + err = vhost_user_get_u64(dev, VHOST_USER_GET_MTU, &dev->mtu); + if (err < 0) { + return err; + } + } } if (dev->migration_blocker == NULL && diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index 1fe5aad..c674a05 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h @@ -51,6 +51,7 @@ struct vhost_dev { uint64_t backend_features; uint64_t protocol_features; uint64_t max_queues; + uint64_t mtu;Just a question why the MTU is stored as a u64? would uint16_t make more sense - then we can be sure we never have an excessively large mtu value. What do you think?
This is because the vihst-user message payload is 64 bits. Note that the max number of queues is also 64 bits. However, a check could be added to ensure the value is coherent. Maxime
