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

[Tiwei Bie <tiwei.bie@intel.com>]

On Mon, Jul 02, 2018 at 10:16:28AM +0200, Maxime Coquelin wrote:
> Signed-off-by: Maxime Coquelin <maxime.coquelin@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);

It should be a space instead of a tab after "vq,"

Why not put "vq, vq->ring_addrs.avail_user_addr,"
and "vhost_iova_to_vva(dev," on the same line?

> +	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,

It's better to put "vhost_iova_to_vva(dev," and
"vq, vq->ring_addrs.used_user_addr," on the same line.

Currently, it looks like something as this in my editor:

¦       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);

> +					&size, VHOST_ACCESS_RW);
> +	if (!vq->device_event || size != req_size)
> +		return -1;
> +
>  	return 0;
>  }
>  
[...]
> @@ -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;
> +
> +

There is no need to have two blank lines.

> +	/*  Flush used desc update. */

Just need one space between "/*" and "Flush".

> +	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);

Maybe it's better to use: RING_EVENT_OFF_MASK

> +	wrap = vq->used_wrap_counter;
> +
> +	if (new < old) {
> +		new += vq->size;
> +		wrap ^= 1;
> +	}
> +
> +	if (wrap != off_wrap >> 15)
> +		off += vq->size;
> +
> +	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 ||

It's better to compare with NULL.

> +				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 ||

It's better to compare with NULL.

> +				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

Normally, we name c/h files as something like: virtio_packed.h

Besides, it'd be better to move the definitions into
vhost.h and define the types and flags for packed
ring only when e.g. VIRTIO_F_RING_PACKED not defined.
Just like how VIRTIO_F_IOMMU_PLATFORM works:

/* Declare IOMMU related bits for older kernels */
#ifndef VIRTIO_F_IOMMU_PLATFORM

#define VIRTIO_F_IOMMU_PLATFORM 33

struct vhost_iotlb_msg {
	__u64 iova;
	__u64 size;
	__u64 uaddr;
#define VHOST_ACCESS_RO      0x1
#define VHOST_ACCESS_WO      0x2
#define VHOST_ACCESS_RW      0x3
	__u8 perm;
#define VHOST_IOTLB_MISS           1
#define VHOST_IOTLB_UPDATE         2
#define VHOST_IOTLB_INVALIDATE     3
#define VHOST_IOTLB_ACCESS_FAIL    4
	__u8 type;
};

#define VHOST_IOTLB_MSG 0x1

struct vhost_msg {
	int type;
	union {
		struct vhost_iotlb_msg iotlb;
		__u8 padding[64];
	};
};
#endif

> @@ -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

RING_EVENT_FLAGS_MASK should be 0x3?

> +#define RING_EVENT_WRAP_MASK 0x8000
> +#define RING_EVENT_OFF_MASK 0x7FFF

It's better to define above macros as VRING_EVENT_*

> +
> +struct vring_packed_desc_event {
> +	uint16_t desc_event_off_wrap;
> +	uint16_t desc_event_flags;
> +};
>  
[...]