[dpdk-dev] [PATCH 2/5] lib/vhost: implement rte_power_monitor API

[Li, Miao]

Hi Chenbo,

> -----Original Message-----
> From: Xia, Chenbo <chenbo.xia at intel.com>
> Sent: Wednesday, September 15, 2021 4:52 PM
> To: Li, Miao <miao.li at intel.com>; dev at dpdk.org
> Cc: maxime.coquelin at redhat.com
> Subject: RE: [PATCH 2/5] lib/vhost: implement rte_power_monitor API
> 
> Hi Miao,
> 
> > -----Original Message-----
> > From: Li, Miao <miao.li at intel.com>
> > Sent: Friday, September 10, 2021 9:06 PM
> > To: dev at dpdk.org
> > Cc: Xia, Chenbo <chenbo.xia at intel.com>; maxime.coquelin at redhat.com;
> > Li, Miao <miao.li at intel.com>
> > Subject: [PATCH 2/5] lib/vhost: implement rte_power_monitor API
> 
> Should be 'vhost: implement rte_power_monitor API'

I will modify it in the next version.

> 
> >
> > This patch defines rte_vhost_power_monitor_cond which is used to pass
> > some information to vhost driver. The information is including the
> > address to monitor, the expected value, the mask to extract value read
> > from 'addr', the flag used to distinguish packed ring or split ring.
> > Vhost driver can use these information to fill rte_power_monitor_cond.
> >
> > Signed-off-by: Miao Li <miao.li at intel.com>
> > ---
> >  lib/vhost/rte_vhost.h | 33 +++++++++++++++++++++++++++++++++
> > lib/vhost/version.map |  3 +++
> >  lib/vhost/vhost.c     | 30 ++++++++++++++++++++++++++++++
> >  3 files changed, 66 insertions(+)
> >
> > diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h index
> > 8d875e9322..f58643b0a3 100644
> > --- a/lib/vhost/rte_vhost.h
> > +++ b/lib/vhost/rte_vhost.h
> > @@ -38,6 +38,8 @@ extern "C" {
> >  #define RTE_VHOST_USER_ASYNC_COPY	(1ULL << 7)
> >  #define RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS	(1ULL << 8)
> >
> > +#define VHOST_POWER_MONITOR_RING_PACKED (1ULL << 0)
> 
> I'd say I don't quite like introducing this flag so that vhost lib app needs to know
> the vring is split or packed. I have another suggestion to do the same thing,
> please check below comment.

Yes, I agree with you. I will remove it in the next version.

> 
> > +
> >  /* Features. */
> >  #ifndef VIRTIO_NET_F_GUEST_ANNOUNCE
> >   #define VIRTIO_NET_F_GUEST_ANNOUNCE 21 @@ -292,6 +294,20 @@
> struct
> > vhost_device_ops {
> >  	void *reserved[1]; /**< Reserved for future extension */  };
> >
> > +/**
> > + * Power monitor condition.
> > + */
> > +struct rte_vhost_power_monitor_cond {
> > +	volatile void *addr;  /**< Address to monitor for changes */
> > +	/**< If the `mask` is non-zero, location pointed
> > +	 *   to by `addr` will be read and compared
> > +	 *   against this value.
> > +	 */
> > +	uint64_t val;
> > +	uint64_t mask; /**< 64-bit mask to extract value read from `addr` */
> > +	uint8_t flag;  /**< if 1, vhost packed ring, otherwise split ring */
> 
> What about define two values instead of the flag. One value for '(value & m) ==
> v ?' is True, another for False.

I think one value to represent true or false is enough. I will fix it in the next version.

> 
> > +};
> > +
> >  /**
> >   * Convert guest physical address to host virtual address
> >   *
> > @@ -914,6 +930,23 @@ int rte_vhost_vring_call(int vid, uint16_t vring_idx);
> >   */
> >  uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid);
> >
> > +/**
> > + * Get power monitor address of the vhost device
> > + *
> > + * @param vid
> > + *  vhost device ID
> > + * @param queue_id
> > + *  vhost queue ID
> > + * @param pmc
> > + *  power monitor condition
> > + * @return
> > + *  0 on success, -1 on failure
> > + */
> > +__rte_experimental
> > +int
> > +rte_vhost_get_monitor_addr(int vid, uint16_t queue_id,
> > +		struct rte_vhost_power_monitor_cond *pmc);
> > +
> >  /**
> >   * Get log base and log size of the vhost device
> >   *
> > diff --git a/lib/vhost/version.map b/lib/vhost/version.map index
> > c92a9d4962..0a9667ef1e 100644
> > --- a/lib/vhost/version.map
> > +++ b/lib/vhost/version.map
> > @@ -85,4 +85,7 @@ EXPERIMENTAL {
> >  	rte_vhost_async_channel_register_thread_unsafe;
> >  	rte_vhost_async_channel_unregister_thread_unsafe;
> >  	rte_vhost_clear_queue_thread_unsafe;
> > +
> > +	# added in 21.11
> > +	rte_vhost_get_monitor_addr;
> >  };
> > diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c index
> > 355ff37651..f7374d3f94 100644
> > --- a/lib/vhost/vhost.c
> > +++ b/lib/vhost/vhost.c
> > @@ -1886,5 +1886,35 @@ int rte_vhost_async_get_inflight(int vid,
> > uint16_t
> > queue_id)
> >  	return ret;
> >  }
> >
> > +int
> > +rte_vhost_get_monitor_addr(int vid, uint16_t queue_id,
> > +		struct rte_vhost_power_monitor_cond *pmc) {
> > +	struct virtio_net *dev = get_device(vid);
> 
> Check dev is not NULL before accessing its member.

I will add dev and queue_id check here in the next version.

> 
> > +	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
> > +	if (vq == NULL)
> > +		return -1;
> > +	if (vq_is_packed(dev)) {
> > +		struct vring_packed_desc *desc;
> > +		desc = vq->desc_packed;
> > +		pmc->addr = &desc[vq->last_avail_idx].flags;
> > +		if (vq->avail_wrap_counter)
> > +			pmc->val = VRING_DESC_F_AVAIL;
> > +		else
> > +			pmc->val = VRING_DESC_F_USED;
> > +		pmc->mask = VRING_DESC_F_AVAIL | VRING_DESC_F_USED;
> > +		pmc->flag = VHOST_POWER_MONITOR_RING_PACKED;
> > +	} else {
> > +		pmc->addr = &vq->avail->idx;
> > +		pmc->val = vq->last_avail_idx & (vq->size - 1);
> > +		pmc->mask = vq->size - 1;
> > +		pmc->flag = 0;
> > +	}
> > +	if (pmc->addr == NULL)
> > +		return -1;
> 
> Is it possible that addr == NULL?

Yes, it is unnecessary. I will delete it in the next version.

Thanks,
Miao

> 
> Thanks,
> Chenbo
> 
> > +
> > +	return 0;
> > +}
> > +
> >  RTE_LOG_REGISTER_SUFFIX(vhost_config_log_level, config, INFO);
> > RTE_LOG_REGISTER_SUFFIX(vhost_data_log_level, data, WARNING);
> > --
> > 2.25.1