[dpdk-dev] [PATCH v6 14/15] vhost: add notification for packed ring

[Jason Wang]

On 2018年07月02日 16:16, Maxime Coquelin wrote:
> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> ---
>   lib/librte_vhost/vhost.c         | 73 ++++++++++++++++++++++++++++++++++++----
>   lib/librte_vhost/vhost.h         | 71 ++++++++++++++++++++++++++++++++++----
>   lib/librte_vhost/vhost_user.c    | 24 +++++++++++++
>   lib/librte_vhost/virtio-packed.h | 11 ++++++
>   lib/librte_vhost/virtio_net.c    | 12 +++----
>   5 files changed, 172 insertions(+), 19 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index 8538302c9..78f20c402 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -171,6 +171,24 @@ vring_translate_packed(struct virtio_net *dev, struct vhost_virtqueue *vq)
>   	if (!vq->desc_packed || size != req_size)
>   		return -1;
>   
> +	req_size = sizeof(struct vring_packed_desc_event);
> +	size = req_size;
> +	vq->driver_event = (struct vring_packed_desc_event *)(uintptr_t)
> +		vhost_iova_to_vva(dev,
> +					vq,	vq->ring_addrs.avail_user_addr,
> +					&size, VHOST_ACCESS_RW);
> +	if (!vq->driver_event || size != req_size)
> +		return -1;
> +
> +	req_size = sizeof(struct vring_packed_desc_event);
> +	size = req_size;
> +	vq->device_event = (struct vring_packed_desc_event *)(uintptr_t)
> +		vhost_iova_to_vva(dev,
> +					vq, vq->ring_addrs.used_user_addr,
> +					&size, VHOST_ACCESS_RW);
> +	if (!vq->device_event || size != req_size)
> +		return -1;
> +
>   	return 0;
>   }
>   
> @@ -595,7 +613,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)
>   	if (!vq)
>   		return -1;
>   
> -	vhost_vring_call(dev, vq);
> +	if (vq_is_packed(dev))
> +		vhost_vring_call_packed(dev, vq);
> +	else
> +		vhost_vring_call_split(dev, vq);
> +
>   	return 0;
>   }
>   
> @@ -616,20 +638,59 @@ rte_vhost_avail_entries(int vid, uint16_t queue_id)
>   	return *(volatile uint16_t *)&vq->avail->idx - vq->last_used_idx;
>   }
>   
> +static inline int
> +vhost_enable_notify_split(struct vhost_virtqueue *vq, int enable)
> +{
> +	if (enable)
> +		vq->used->flags &= ~VRING_USED_F_NO_NOTIFY;
> +	else
> +		vq->used->flags |= VRING_USED_F_NO_NOTIFY;
> +
> +	return 0;
> +}
> +
> +static inline int
> +vhost_enable_notify_packed(struct virtio_net *dev,
> +		struct vhost_virtqueue *vq, int enable)
> +{
> +	uint16_t flags;
> +
> +	if (!enable) {
> +		vq->device_event->desc_event_flags = RING_EVENT_FLAGS_DISABLE;
> +		return 0;
> +	}
> +
> +	flags = RING_EVENT_FLAGS_ENABLE;
> +	if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> +		flags = RING_EVENT_FLAGS_DESC;
> +		vq->device_event->desc_event_off_wrap = vq->last_avail_idx |
> +			vq->avail_wrap_counter << 15;
> +	}
> +
> +	rte_smp_wmb();
> +
> +	vq->device_event->desc_event_flags = flags;
> +
> +	rte_smp_wmb();
> +
> +	return 0;
> +}
> +
>   int
>   rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable)
>   {
>   	struct virtio_net *dev = get_device(vid);
> +	struct vhost_virtqueue *vq;
>   
>   	if (!dev)
>   		return -1;
>   
> -	if (enable)
> -		dev->virtqueue[queue_id]->used->flags &=
> -			~VRING_USED_F_NO_NOTIFY;
> +	vq = dev->virtqueue[queue_id];
> +
> +	if (vq_is_packed(dev))
> +		return vhost_enable_notify_packed(dev, vq, enable);
>   	else
> -		dev->virtqueue[queue_id]->used->flags |= VRING_USED_F_NO_NOTIFY;
> -	return 0;
> +		return vhost_enable_notify_split(vq, enable);
>   }
>   
>   void
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 6ea8fb896..728fd2f6b 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -21,6 +21,7 @@
>   
>   #include "rte_vhost.h"
>   #include "rte_vdpa.h"
> +#include "virtio-packed.h"
>   
>   /* Used to indicate that the device is running on a data core */
>   #define VIRTIO_DEV_RUNNING 1
> @@ -95,8 +96,14 @@ struct vhost_virtqueue {
>   		struct vring_desc	*desc;
>   		struct vring_desc_packed   *desc_packed;
>   	};
> -	struct vring_avail	*avail;
> -	struct vring_used	*used;
> +	union {
> +		struct vring_avail	*avail;
> +		struct vring_packed_desc_event *driver_event;
> +	};
> +	union {
> +		struct vring_used	*used;
> +		struct vring_packed_desc_event *device_event;
> +	};
>   	uint32_t		size;
>   
>   	uint16_t		last_avail_idx;
> @@ -613,7 +620,7 @@ vhost_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old)
>   }
>   
>   static __rte_always_inline void
> -vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq)
> +vhost_vring_call_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
>   {
>   	/* Flush used->idx update before we read avail->flags. */
>   	rte_mb();
> @@ -624,11 +631,11 @@ vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq)
>   		uint16_t new = vq->last_used_idx;
>   
>   		VHOST_LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n",
> -			__func__,
> -			vhost_used_event(vq),
> -			old, new);
> +				__func__,
> +				vhost_used_event(vq),
> +				old, new);
>   		if (vhost_need_event(vhost_used_event(vq), new, old)
> -			&& (vq->callfd >= 0)) {
> +				&& (vq->callfd >= 0)) {
>   			vq->signalled_used = vq->last_used_idx;
>   			eventfd_write(vq->callfd, (eventfd_t) 1);
>   		}

Looks like a style fixes, move those to another patch?

> @@ -640,4 +647,54 @@ vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq)
>   	}
>   }
>   
> +static __rte_always_inline void
> +vhost_vring_call_packed(struct virtio_net *dev, struct vhost_virtqueue *vq)
> +{
> +	uint16_t old, new, off, off_wrap, wrap;
> +	bool kick = false;
> +
> +
> +	/*  Flush used desc update. */
> +	rte_smp_mb();
> +
> +	if (!(dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))) {
> +		if (vq->driver_event->desc_event_flags !=
> +				RING_EVENT_FLAGS_DISABLE)
> +			kick = true;
> +		goto kick;
> +	}
> +
> +	old = vq->signalled_used;
> +	new = vq->last_used_idx;
> +	vq->signalled_used = new;
> +
> +	if (vq->driver_event->desc_event_flags != RING_EVENT_FLAGS_DESC) {
> +		if (vq->driver_event->desc_event_flags !=
> +				RING_EVENT_FLAGS_DISABLE)
> +			kick = true;
> +		goto kick;
> +	}
> +
> +	rte_smp_rmb();
> +
> +	off_wrap = vq->driver_event->desc_event_off_wrap;
> +	off = off_wrap & ~(1 << 15);
> +	wrap = vq->used_wrap_counter;
> +
> +	if (new < old) {
> +		new += vq->size;
> +		wrap ^= 1;
> +	}
> +
> +	if (wrap != off_wrap >> 15)
> +		off += vq->size;
> +

Jusy FYI. Maybe we can switch to a more compact version like Tiwei used:

...
         wrap_counter = off_wrap >> 15;
         event_idx = off_wrap & ~(1<<15);
         if (wrap_counter != vq->avail_wrap_counter)
                 event_idx -= vq->vring_packed.num;

         if (flags == VRING_EVENT_F_DESC)
                 needs_kick = vring_need_event(event_idx, new, old);
         else
                 needs_kick = (flags != VRING_EVENT_F_DISABLE);

(I've switched to this version in vhost).

Thanks

> +	if (vhost_need_event(off, new, old))
> +		kick = true;
> +
> +kick:
> +	if (kick)
> +		eventfd_write(vq->callfd, (eventfd_t)1);
> +}
> +
>   #endif /* _VHOST_NET_CDEV_H_ */
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index b2b57de57..bda515bdb 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -523,6 +523,30 @@ translate_ring_addresses(struct virtio_net *dev, int vq_index)
>   		vq = dev->virtqueue[vq_index];
>   		addr = &vq->ring_addrs;
>   
> +		len = sizeof(struct vring_packed_desc_event);
> +		vq->driver_event = (struct vring_packed_desc_event *)
> +					(uintptr_t)ring_addr_to_vva(dev,
> +					vq, addr->avail_user_addr, &len);
> +		if (vq->driver_event == 0 ||
> +				len != sizeof(struct vring_packed_desc_event)) {
> +			RTE_LOG(DEBUG, VHOST_CONFIG,
> +				"(%d) failed to find driver area address.\n",
> +				dev->vid);
> +			return dev;
> +		}
> +
> +		len = sizeof(struct vring_packed_desc_event);
> +		vq->device_event = (struct vring_packed_desc_event *)
> +					(uintptr_t)ring_addr_to_vva(dev,
> +					vq, addr->used_user_addr, &len);
> +		if (vq->device_event == 0 ||
> +				len != sizeof(struct vring_packed_desc_event)) {
> +			RTE_LOG(DEBUG, VHOST_CONFIG,
> +				"(%d) failed to find device area address.\n",
> +				dev->vid);
> +			return dev;
> +		}
> +
>   		return dev;
>   	}
>   
> diff --git a/lib/librte_vhost/virtio-packed.h b/lib/librte_vhost/virtio-packed.h
> index d386cb6df..ce3b28313 100644
> --- a/lib/librte_vhost/virtio-packed.h
> +++ b/lib/librte_vhost/virtio-packed.h
> @@ -19,6 +19,17 @@ struct vring_desc_packed {
>   	uint16_t flags;
>   };
>   
> +#define RING_EVENT_FLAGS_ENABLE 0x0
> +#define RING_EVENT_FLAGS_DISABLE 0x1
> +#define RING_EVENT_FLAGS_DESC 0x2
> +#define RING_EVENT_FLAGS_MASK 0xFFFC
> +#define RING_EVENT_WRAP_MASK 0x8000
> +#define RING_EVENT_OFF_MASK 0x7FFF
> +
> +struct vring_packed_desc_event {
> +	uint16_t desc_event_off_wrap;
> +	uint16_t desc_event_flags;
> +};
>   
>   static inline bool
>   desc_is_avail(struct vring_desc_packed *desc, bool wrap_counter)
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 03dd38235..11c10aaf8 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -824,7 +824,7 @@ virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   
>   	if (likely(vq->shadow_used_idx)) {
>   		flush_shadow_used_ring_split(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_split(dev, vq);
>   	}
>   
>   	return pkt_idx;
> @@ -877,7 +877,7 @@ virtio_dev_rx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   
>   	if (likely(vq->shadow_used_idx)) {
>   		flush_shadow_used_ring_packed(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_packed(dev, vq);
>   	}
>   
>   	return pkt_idx;
> @@ -1360,7 +1360,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   		}
>   
>   		flush_shadow_used_ring_split(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_split(dev, vq);
>   	}
>   
>   	rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
> @@ -1439,7 +1439,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   		if (unlikely(i < count))
>   			vq->shadow_used_idx = i;
>   		flush_shadow_used_ring_split(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_split(dev, vq);
>   	}
>   
>   	return i;
> @@ -1477,7 +1477,7 @@ virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   		}
>   
>   		flush_shadow_used_ring_packed(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_packed(dev, vq);
>   	}
>   
>   	VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
> @@ -1555,7 +1555,7 @@ virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   		if (unlikely(i < count))
>   			vq->shadow_used_idx = i;
>   		flush_shadow_used_ring_packed(dev, vq);
> -		vhost_vring_call(dev, vq);
> +		vhost_vring_call_packed(dev, vq);
>   	}
>   
>   	return i;