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

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 07/03/2018 08:06 AM, Jason Wang wrote:
> 
> 
> On 2018年07月02日 16:16, 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);
>> +    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?

Indeed, I'll remove this style fixes in next version.

>> @@ -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).

Sure, it is indeed simpler.

Thanks,
Maxime

> 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;
>