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

[Marc-André Lureau]

Hi

On Mon, Jun 4, 2018 at 11:07 AM, Dr. David Alan Gilbert
<address@hidden> wrote:
> * Marc-André Lureau (address@hidden) 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?
>

A similar message could be used for plain vhost, in some ioctl form.
Here we are documenting vhost-user protocol only.


Thanks

> Dave
>
>
>> Signed-off-by: Marc-André Lureau <address@hidden>
>> ---
>>  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 / address@hidden / Manchester, UK