Re: [Qemu-devel] [PATCH] virtio: add support for in-order feature

[Michael S. Tsirkin]

On Thu, Aug 09, 2018 at 07:54:37PM +0300, Ilya Maximets wrote:
> New feature bit for in-order feature of the upcoming
> virtio 1.1. It's already supported by DPDK vhost-user
> and virtio implementations. These changes required to
> allow feature negotiation.
> 
> Signed-off-by: Ilya Maximets <address@hidden>
> ---
> 
> I just wanted to test this new feature in DPDK but failed
> to found required patch for QEMU side. So, I implemented it.
> At least it will be helpful for someone like me, who wants
> to evaluate VIRTIO_F_IN_ORDER with DPDK.
> 
>  hw/net/vhost_net.c                             |  1 +
>  include/hw/virtio/virtio.h                     | 12 +++++++-----
>  include/standard-headers/linux/virtio_config.h |  7 +++++++
>  3 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index e037db6..86879c5 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -78,6 +78,7 @@ static const int user_feature_bits[] = {
>      VIRTIO_NET_F_MRG_RXBUF,
>      VIRTIO_NET_F_MTU,
>      VIRTIO_F_IOMMU_PLATFORM,
> +    VIRTIO_F_IN_ORDER,
>  
>      /* This bit implies RARP isn't sent by QEMU out of band */
>      VIRTIO_NET_F_GUEST_ANNOUNCE,
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 9c1fa07..a422025 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -254,16 +254,18 @@ typedef struct virtio_input_conf virtio_input_conf;
>  typedef struct VirtIOSCSIConf VirtIOSCSIConf;
>  typedef struct VirtIORNGConf VirtIORNGConf;
>  
> -#define DEFINE_VIRTIO_COMMON_FEATURES(_state, _field) \
> +#define DEFINE_VIRTIO_COMMON_FEATURES(_state, _field)     \
>      DEFINE_PROP_BIT64("indirect_desc", _state, _field,    \
>                        VIRTIO_RING_F_INDIRECT_DESC, true), \
>      DEFINE_PROP_BIT64("event_idx", _state, _field,        \
>                        VIRTIO_RING_F_EVENT_IDX, true),     \
>      DEFINE_PROP_BIT64("notify_on_empty", _state, _field,  \
> -                      VIRTIO_F_NOTIFY_ON_EMPTY, true), \
> -    DEFINE_PROP_BIT64("any_layout", _state, _field, \
> -                      VIRTIO_F_ANY_LAYOUT, true), \
> -    DEFINE_PROP_BIT64("iommu_platform", _state, _field, \
> +                      VIRTIO_F_NOTIFY_ON_EMPTY, true),    \
> +    DEFINE_PROP_BIT64("any_layout", _state, _field,       \
> +                      VIRTIO_F_ANY_LAYOUT, true),         \
> +    DEFINE_PROP_BIT64("in_order", _state, _field,         \
> +                      VIRTIO_F_IN_ORDER, true),           \
> +    DEFINE_PROP_BIT64("iommu_platform", _state, _field,   \
>                        VIRTIO_F_IOMMU_PLATFORM, false)

Is in_order really right for all virtio devices?

>  hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
> diff --git a/include/standard-headers/linux/virtio_config.h 
> b/include/standard-headers/linux/virtio_config.h
> index b777069..d20398c 100644
> --- a/include/standard-headers/linux/virtio_config.h
> +++ b/include/standard-headers/linux/virtio_config.h
> @@ -71,4 +71,11 @@
>   * this is for compatibility with legacy systems.
>   */
>  #define VIRTIO_F_IOMMU_PLATFORM              33
> +
> +/*
> + * Inorder feature indicates that all buffers are used by the device
> + * in the same order in which they have been made available.
> + */
> +#define VIRTIO_F_IN_ORDER 35
> +
>  #endif /* _LINUX_VIRTIO_CONFIG_H */
> -- 
> 2.7.4