Re: [Qemu-devel] [PATCH v6 6/8] Add vhost-user calls implementation

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jan 13, 2014 at 03:25:17PM +0100, Antonios Motakis wrote:
> Each ioctl request of vhost-kernel has a vhost-user message equivalent,
> which is sent over the control socket.
> 
> The general approach is to copy the data from the supplied argument
> pointer to a designated field in the message. If a file descriptor is
> to be passed it will be placed in the fds array for inclusion in
> the sendmsd control header.
> 
> VHOST_SET_MEM_TABLE ignores the supplied vhost_memory structure and scans
> the global ram_list for ram blocks with a valid fd field set. This would
> be set when the -mem-path option with shared=on property is used.
> 
> Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>

the name vhost-backend and vhost-user is unfortunate as you let some
net specific stuff get in there.

> ---
>  hw/virtio/vhost-backend.c | 147 ++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 143 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 460ee02..8f98562 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -81,6 +81,39 @@ static VhostUserMsg m __attribute__ ((unused));
>  /* The version of the protocol we support */
>  #define VHOST_USER_VERSION    (0x1)
>  
> +static unsigned long int ioctl_to_vhost_user_request[VHOST_USER_MAX] = {
> +    -1, /* VHOST_USER_NONE */
> +    VHOST_GET_FEATURES, /* VHOST_USER_GET_FEATURES */
> +    VHOST_SET_FEATURES, /* VHOST_USER_SET_FEATURES */
> +    VHOST_SET_OWNER, /* VHOST_USER_SET_OWNER */
> +    VHOST_RESET_OWNER, /* VHOST_USER_RESET_OWNER */
> +    VHOST_SET_MEM_TABLE, /* VHOST_USER_SET_MEM_TABLE */
> +    VHOST_SET_LOG_BASE, /* VHOST_USER_SET_LOG_BASE */
> +    VHOST_SET_LOG_FD, /* VHOST_USER_SET_LOG_FD */
> +    VHOST_SET_VRING_NUM, /* VHOST_USER_SET_VRING_NUM */
> +    VHOST_SET_VRING_ADDR, /* VHOST_USER_SET_VRING_ADDR */
> +    VHOST_SET_VRING_BASE, /* VHOST_USER_SET_VRING_BASE */
> +    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_NET_SET_BACKEND, /* VHOST_USER_NET_SET_BACKEND */
> +    -1 /* VHOST_USER_ECHO */
> +};
> +
> +static VhostUserRequest vhost_user_request_translate(unsigned long int request)
> +{
> +    VhostUserRequest idx;
> +
> +    for (idx = 0; idx < VHOST_USER_MAX; idx++) {
> +        if (ioctl_to_vhost_user_request[idx] == request) {
> +            break;
> +        }
> +    }
> +
> +    return (idx == VHOST_USER_MAX) ? VHOST_USER_NONE : idx;
> +}
> +
>  static int vhost_user_recv(int fd, VhostUserMsg *msg)
>  {
>      ssize_t r;
> @@ -235,7 +268,10 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>  {
>      int fd = dev->control;
>      VhostUserMsg msg;
> -    int result = 0;
> +    VhostUserRequest msg_request;
> +    RAMBlock *block = 0;
> +    struct vhost_vring_file *file = 0;
> +    int need_reply = 0;
>      int fds[VHOST_MEMORY_MAX_NREGIONS];
>      size_t fd_num = 0;
>  
> @@ -245,20 +281,123 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>          return 0;
>      }
>  
> -    msg.request = VHOST_USER_NONE;
> +    msg_request = vhost_user_request_translate(request);
> +    msg.request = msg_request;
>      msg.flags = VHOST_USER_VERSION;
>      msg.size = 0;
>  
>      switch (request) {
> +    case VHOST_GET_FEATURES:
> +    case VHOST_GET_VRING_BASE:
> +        need_reply = 1;
> +        break;
> +
> +    case VHOST_SET_FEATURES:
> +    case VHOST_SET_LOG_BASE:
> +        msg.u64 = *((__u64 *) arg);
> +        msg.size = sizeof(m.u64);
> +        break;
> +
> +    case VHOST_SET_OWNER:
> +    case VHOST_RESET_OWNER:
> +        break;
> +
> +    case VHOST_SET_MEM_TABLE:
> +        QTAILQ_FOREACH(block, &ram_list.blocks, next)
> +        {
> +            if (block->fd > 0) {
> +                msg.memory.regions[fd_num].userspace_addr = (__u64) block->host;
> +                msg.memory.regions[fd_num].memory_size = block->length;
> +                msg.memory.regions[fd_num].guest_phys_addr = block->offset;
> +                fds[fd_num++] = block->fd;
> +            }
> +        }
> +
> +        msg.memory.nregions = fd_num;
> +
> +        if (!fd_num) {
> +            error_report("Failed initializing vhost-user memory map\n"
> +                    "consider using -mem-path option\n");
> +            return -1;
> +        }
> +
> +        msg.size = sizeof(m.memory.nregions);
> +        msg.size += sizeof(m.memory.padding);
> +        msg.size += fd_num * sizeof(VhostUserMemoryRegion);
> +
> +        break;
> +
> +    case VHOST_SET_LOG_FD:
> +        fds[fd_num++] = *((int *) arg);
> +        break;
> +
> +    case VHOST_SET_VRING_NUM:
> +    case VHOST_SET_VRING_BASE:
> +        memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
> +        msg.size = sizeof(m.state);
> +        break;
> +
> +    case VHOST_SET_VRING_ADDR:
> +        memcpy(&msg.addr, arg, sizeof(struct vhost_vring_addr));
> +        msg.size = sizeof(m.addr);
> +        break;
> +
> +    case VHOST_SET_VRING_KICK:
> +    case VHOST_SET_VRING_CALL:
> +    case VHOST_SET_VRING_ERR:
> +    case VHOST_NET_SET_BACKEND:
> +        file = arg;
> +        msg.u64 = file->index;
> +        msg.size = sizeof(m.u64);
> +        if (file->fd > 0) {
> +            fds[fd_num++] = file->fd;
> +        }
> +        break;
>      default:
>          error_report("vhost-user trying to send unhandled ioctl\n");
>          return -1;
>          break;
>      }
>  
> -    result = vhost_user_send_fds(fd, &msg, fds, fd_num);
> +    if (vhost_user_send_fds(fd, &msg, fds, fd_num) < 0) {
> +        return -1;
> +    }
>  
> -    return result;
> +    if (need_reply) {
> +        if (vhost_user_recv(fd, &msg) < 0) {
> +            return -1;
> +        }
> +
> +        if (msg_request != msg.request) {
> +            error_report("Received unexpected msg type."
> +                         " Expected %d received %d\n",
> +                         msg_request, msg.request);
> +            return -1;
> +        }
> +
> +        switch (msg_request) {
> +        case VHOST_USER_GET_FEATURES:
> +            if (msg.size != sizeof(m.u64)) {
> +                error_report("Received bad msg size.\n");
> +                return -1;
> +            }
> +            *((__u64 *) arg) = msg.u64;
> +            break;
> +        case VHOST_USER_GET_VRING_BASE:
> +            if (msg.size != sizeof(m.state)) {
> +                error_report("Received bad msg size.\n");
> +                return -1;
> +            }
> +            memcpy(arg, &msg.state, sizeof(struct vhost_vring_state));
> +            break;
> +        default:
> +            error_report("Received unexpected msg type.\n");
> +            return -1;
> +            break;
> +        }
> +    }
> +
> +    return 0;
>  }
>  
>  static int vhost_user_init(struct vhost_dev *dev, const char *devpath)
> -- 
> 1.8.3.2
>