On 12/02/2015 05:43 AM, Yuanhan Liu wrote:
> VHOST_USER_SET_LOG_BASE request is used to tell the backend (dpdk
> vhost-user) where we should log dirty pages, and how big the log
> buffer is.
>
> This request introduces a new payload:
>
>       typedef struct VhostUserLog {
>               uint64_t mmap_size;
>               uint64_t mmap_offset;
>       } VhostUserLog;
>
> Also, a fd is delivered from QEMU by ancillary data.
>
> With those info given, an area of memory is mmaped, assigned
> to dev->log_base, for logging dirty pages.
>
> Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
> ---
>   lib/librte_vhost/rte_virtio_net.h             |  2 ++
>   lib/librte_vhost/vhost_user/vhost-net-user.c  |  7 ++++-
>   lib/librte_vhost/vhost_user/vhost-net-user.h  |  6 ++++
>   lib/librte_vhost/vhost_user/virtio-net-user.c | 44 
> +++++++++++++++++++++++++++
>   lib/librte_vhost/vhost_user/virtio-net-user.h |  1 +
>   5 files changed, 59 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/rte_virtio_net.h 
> b/lib/librte_vhost/rte_virtio_net.h
> index 5687452..416dac2 100644
> --- a/lib/librte_vhost/rte_virtio_net.h
> +++ b/lib/librte_vhost/rte_virtio_net.h
> @@ -127,6 +127,8 @@ struct virtio_net {
>   #define IF_NAME_SZ (PATH_MAX > IFNAMSIZ ? PATH_MAX : IFNAMSIZ)
>       char                    ifname[IF_NAME_SZ];     /**< Name of the tap 
> device or socket path. */
>       uint32_t                virt_qp_nb;     /**< number of queue pair we 
> have allocated */
> +     uint64_t                log_size;       /**< Size of log area */
> +     uint8_t                 *log_base;      /**< Where dirty pages are 
> logged */
>       void                    *priv;          /**< private context */
>       struct vhost_virtqueue  *virtqueue[VHOST_MAX_QUEUE_PAIRS * 2];  /**< 
> Contains all virtqueue information. */
>   } __rte_cache_aligned;

This (and other changes in patch 2 breaks the librte_vhost ABI again, so 
you'd need to at least add a deprecation note to 2.2 to be able to do it 
in 2.3 at all according to the ABI policy.

Perhaps a better option would be adding some padding to the structs now 
for 2.2 since the vhost ABI is broken there anyway. That would at least 
give a chance to keep it compatible from 2.2 to 2.3.

        - Panu -


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