Re: [Qemu-devel] [RFC v2 06/12] vhost-user: add vhost_user_input_get_config()

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Marc-André Lureau (marcandre.lureau@redhat.com) wrote:
> Ask vhost user input backend the list of virtio_input_config.

Why is this vhost-user specific; shouldn't the vhost-input
behaviour be the same irrespective of if it's vhost-user or plain vhost?

Dave


> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/hw/virtio/vhost-backend.h |  4 +++
>  hw/virtio/vhost-user.c            | 59 +++++++++++++++++++++++++++++++
>  docs/interop/vhost-user.txt       |  6 ++++
>  3 files changed, 69 insertions(+)
> 
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index 5dac61f9ea..6cc2edacc5 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -12,6 +12,7 @@
>  #define VHOST_BACKEND_H
>  
>  #include "exec/memory.h"
> +#include "standard-headers/linux/virtio_input.h"
>  
>  typedef enum VhostBackendType {
>      VHOST_BACKEND_TYPE_NONE = 0,
> @@ -156,4 +157,7 @@ int vhost_backend_invalidate_device_iotlb(struct vhost_dev *dev,
>  int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
>                                            struct vhost_iotlb_msg *imsg);
>  
> +int vhost_user_input_get_config(struct vhost_dev *dev,
> +                                struct virtio_input_config **config);
> +
>  #endif /* VHOST_BACKEND_H */
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index a87db01e55..19ed87d07c 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -84,6 +84,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_POSTCOPY_ADVISE  = 28,
>      VHOST_USER_POSTCOPY_LISTEN  = 29,
>      VHOST_USER_POSTCOPY_END     = 30,
> +    VHOST_USER_INPUT_GET_CONFIG,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>  
> @@ -324,6 +325,64 @@ static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
>      return 0;
>  }
>  
> +static void *vhost_user_read_size(struct vhost_dev *dev, uint32_t size)
> +{
> +    struct vhost_user *u = dev->opaque;
> +    CharBackend *chr = u->chr;
> +    int r;
> +    uint8_t *p = g_malloc(size);
> +
> +    r = qemu_chr_fe_read_all(chr, p, size);
> +    if (r != size) {
> +        error_report("Failed to read msg payload."
> +                     " Read %d instead of %d.", r, size);
> +        return NULL;
> +    }
> +
> +    return p;
> +}
> +
> +int vhost_user_input_get_config(struct vhost_dev *dev,
> +                                struct virtio_input_config **config)
> +{
> +    void *p = NULL;
> +    VhostUserMsg msg = {
> +        .hdr.request = VHOST_USER_INPUT_GET_CONFIG,
> +        .hdr.flags = VHOST_USER_VERSION,
> +    };
> +
> +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> +        goto err;
> +    }
> +
> +    if (vhost_user_read_header(dev, &msg) < 0) {
> +        goto err;
> +    }
> +
> +    p = vhost_user_read_size(dev, msg.hdr.size);
> +    if (!p) {
> +        goto err;
> +    }
> +
> +    if (msg.hdr.request != VHOST_USER_INPUT_GET_CONFIG) {
> +        error_report("Received unexpected msg type. Expected %d received %d",
> +                     VHOST_USER_INPUT_GET_CONFIG, msg.hdr.request);
> +        goto err;
> +    }
> +
> +    if (msg.hdr.size % sizeof(struct virtio_input_config)) {
> +        error_report("Invalid msg size");
> +        goto err;
> +    }
> +
> +    *config = p;
> +    return msg.hdr.size / sizeof(struct virtio_input_config);
> +
> +err:
> +    g_free(p);
> +    return -1;
> +}
> +
>  static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
>                                     struct vhost_log *log)
>  {
> diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> index 534caab18a..3df9927386 100644
> --- a/docs/interop/vhost-user.txt
> +++ b/docs/interop/vhost-user.txt
> @@ -744,6 +744,12 @@ Master message types
>        was previously sent.
>        The value returned is an error indication; 0 is success.
>  
> + * VHOST_USER_INPUT_GET_CONFIG
> +
> +      Slave payload: (struct virtio_input_config)*
> +
> +      Ask vhost user input backend the list of virtio_input_config.
> +
>  Slave message types
>  -------------------
>  
> -- 
> 2.17.1.906.g10fd178552
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK