RE: [PATCH 1/1] net/mana: add 32 bit short doorbell

[Wei Hu <weh@microsoft.com>]

> -----Original Message-----
> From: Long Li <longli@microsoft.com>
> Sent: Tuesday, September 19, 2023 4:02 AM
> To: Wei Hu <weh@microsoft.com>; dev@dpdk.org
> Cc: stable@dpdk.org; Ferruh Yigit <ferruh.yigit@amd.com>; Luca Boccassi
> <bluca@debian.org>; Kevin Traynor <ktraynor@redhat.com>
> Subject: RE: [PATCH 1/1] net/mana: add 32 bit short doorbell
> 
> > Subject: [PATCH 1/1] net/mana: add 32 bit short doorbell
> >
> > Add 32 bit short doorbell support. Ring short doorbell when running in
> > 32 bit applicactions.
> >
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Wei Hu <weh@microsoft.com>
> > ---
> >  drivers/net/mana/gdma.c | 95
> > +++++++++++++++++++++++++++++++++++++++++
> >  drivers/net/mana/mana.h | 25 +++++++++++
> >  drivers/net/mana/rx.c   | 52 ++++++++++++++++++++++
> >  drivers/net/mana/tx.c   | 28 ++++++++++++
> >  4 files changed, 200 insertions(+)
> >
> > diff --git a/drivers/net/mana/gdma.c b/drivers/net/mana/gdma.c index
> > 65685fe236..d1da025d1b 100644
> > --- a/drivers/net/mana/gdma.c
> > +++ b/drivers/net/mana/gdma.c
> > @@ -166,6 +166,97 @@ gdma_post_work_request(struct
> mana_gdma_queue
> > *queue,
> >  	return 0;
> >  }
> >
> > +#ifdef RTE_ARCH_32
> > +union gdma_short_doorbell_entry {
> > +	uint32_t     as_uint32;
> > +
> > +	struct {
> > +		uint32_t tail_ptr_incr	: 16; /* Number of CQEs */
> > +		uint32_t id		: 12;
> > +		uint32_t reserved	: 3;
> > +		uint32_t arm		: 1;
> > +	} cq;
> > +
> > +	struct {
> > +		uint32_t tail_ptr_incr	: 16; /* In number of bytes */
> > +		uint32_t id		: 12;
> > +		uint32_t reserved	: 4;
> > +	} rq;
> > +
> > +	struct {
> > +		uint32_t tail_ptr_incr	: 16; /* In number of bytes */
> > +		uint32_t id		: 12;
> > +		uint32_t reserved	: 4;
> > +	} sq;
> > +
> > +	struct {
> > +		uint32_t tail_ptr_incr	: 16; /* Number of EQEs */
> > +		uint32_t id		: 12;
> > +		uint32_t reserved	: 3;
> > +		uint32_t arm		: 1;
> > +	} eq;
> > +}; /* HW DATA */
> > +
> > +enum {
> > +	DOORBELL_SHORT_OFFSET_SQ = 0x10,
> > +	DOORBELL_SHORT_OFFSET_RQ = 0x410,
> > +	DOORBELL_SHORT_OFFSET_CQ = 0x810,
> > +	DOORBELL_SHORT_OFFSET_EQ = 0xFF0,
> > +};
> > +
> > +/*
> > + * Write to hardware doorbell to notify new activity.
> > + */
> > +int
> > +mana_ring_short_doorbell(void *db_page, enum gdma_queue_types
> > queue_type,
> > +			 uint32_t queue_id, uint32_t tail_incr, uint8_t arm) {
> > +	uint8_t *addr = db_page;
> > +	union gdma_short_doorbell_entry e = {};
> > +
> > +	if ((queue_id & ~GDMA_SHORT_DB_QID_MASK) ||
> > +	    (tail_incr & ~GDMA_SHORT_DB_INC_MASK)) {
> > +		DP_LOG(ERR, "%s: queue_id %u or "
> > +		       "tail_incr %u overflowed, queue type %d",
> > +		       __func__, queue_id, tail_incr, queue_type);
> > +		return -EINVAL;
> > +	}
> > +
> > +	switch (queue_type) {
> > +	case GDMA_QUEUE_SEND:
> > +		e.sq.id = queue_id;
> > +		e.sq.tail_ptr_incr = tail_incr;
> > +		addr += DOORBELL_SHORT_OFFSET_SQ;
> > +		break;
> > +
> > +	case GDMA_QUEUE_RECEIVE:
> > +		e.rq.id = queue_id;
> > +		e.rq.tail_ptr_incr = tail_incr;
> > +		addr += DOORBELL_SHORT_OFFSET_RQ;
> > +		break;
> > +
> > +	case GDMA_QUEUE_COMPLETION:
> > +		e.cq.id = queue_id;
> > +		e.cq.tail_ptr_incr = tail_incr;
> > +		e.cq.arm = arm;
> > +		addr += DOORBELL_SHORT_OFFSET_CQ;
> > +		break;
> > +
> > +	default:
> > +		DP_LOG(ERR, "Unsupported queue type %d", queue_type);
> > +		return -1;
> > +	}
> > +
> > +	/* Ensure all writes are done before ringing doorbell */
> > +	rte_wmb();
> > +
> > +	DP_LOG(DEBUG, "db_page %p addr %p queue_id %u type %u tail %u
> > arm %u",
> > +	       db_page, addr, queue_id, queue_type, tail_incr, arm);
> > +
> > +	rte_write32(e.as_uint32, addr);
> > +	return 0;
> > +}
> > +#else
> >  union gdma_doorbell_entry {
> >  	uint64_t     as_uint64;
> >
> > @@ -248,6 +339,7 @@ mana_ring_doorbell(void *db_page, enum
> > gdma_queue_types queue_type,
> >  	rte_write64(e.as_uint64, addr);
> >  	return 0;
> >  }
> > +#endif
> >
> >  /*
> >   * Poll completion queue for completions.
> > @@ -287,6 +379,9 @@ gdma_poll_completion_queue(struct
> mana_gdma_queue
> > *cq,
> >  		num_comp++;
> >
> >  		cq->head++;
> > +#ifdef RTE_ARCH_32
> > +		cq->head_incr_to_short_db++;
> > +#endif
> >
> >  		DP_LOG(DEBUG, "comp new 0x%x old 0x%x cqe 0x%x wq %u
> sq %u head
> > %u",
> >  		       new_owner_bits, old_owner_bits, cqe_owner_bits, diff --
> git
> > a/drivers/net/mana/mana.h b/drivers/net/mana/mana.h index
> > 5801491d75..848d87c096 100644
> > --- a/drivers/net/mana/mana.h
> > +++ b/drivers/net/mana/mana.h
> > @@ -50,6 +50,19 @@ struct mana_shared_data {  #define
> MAX_TX_WQE_SIZE
> > 512  #define MAX_RX_WQE_SIZE 256
> >
> > +/* For 32 bit only */
> > +#ifdef RTE_ARCH_32
> > +#define	GDMA_SHORT_DB_INC_MASK 0xffff
> > +#define	GDMA_SHORT_DB_QID_MASK 0xfff
> > +
> > +#define GDMA_SHORT_DB_MAX_WQE	(0x10000 /
> > GDMA_WQE_ALIGNMENT_UNIT_SIZE)
> > +
> > +#define TX_WQE_SHORT_DB_THRESHOLD \
> > +	(GDMA_SHORT_DB_MAX_WQE - (2 * MAX_TX_WQE_SIZE)) #define
> > +RX_WQE_SHORT_DB_THRESHOLD \
> 
> GDMA_SHORT_DB_MAX_WQE is in BU, MAX_TX_WQE_SIZE is in bytes.
> 
> Doing math on two different units...
> 
That is good point. I will correct this.

> And why using "2*", using "1*" is good enough?
> 
> 
Sure. I will use 1 in next revision.

> 
> 
> > +	(GDMA_SHORT_DB_MAX_WQE - (2 * MAX_RX_WQE_SIZE)) #endif
> > +
> >  /* Values from the GDMA specification document, WQE format
> > description */ #define INLINE_OOB_SMALL_SIZE_IN_BYTES 8  #define
> > INLINE_OOB_LARGE_SIZE_IN_BYTES 24 @@ -375,6 +388,9 @@ struct
> > mana_gdma_queue {
> >  	uint32_t id;
> >  	uint32_t head;
> >  	uint32_t tail;
> > +#ifdef RTE_ARCH_32
> > +	uint32_t head_incr_to_short_db;
> > +#endif
> >  };
> >
> >  #define MANA_MR_BTREE_PER_QUEUE_N	64
> > @@ -425,6 +441,9 @@ struct mana_rxq {
> >  	 */
> >  	uint32_t desc_ring_head, desc_ring_tail;
> >
> > +	/* For storing wqe increment count btw each short doorbell ring */
> > +	uint32_t wqe_cnt_to_short_db;
> > +
> >  	struct mana_gdma_queue gdma_rq;
> >  	struct mana_gdma_queue gdma_cq;
> >  	struct gdma_comp *gdma_comp_buf;
> > @@ -455,8 +474,14 @@ extern int mana_logtype_init;
> >
> >  #define PMD_INIT_FUNC_TRACE() PMD_INIT_LOG(DEBUG, " >>")
> >
> > +#ifdef RTE_ARCH_32
> > +int mana_ring_short_doorbell(void *db_page, enum gdma_queue_types
> > queue_type,
> > +			     uint32_t queue_id, uint32_t tail_incr,
> > +			     uint8_t arm);
> > +#else
> >  int mana_ring_doorbell(void *db_page, enum gdma_queue_types
> > queue_type,
> >  		       uint32_t queue_id, uint32_t tail, uint8_t arm);
> > +#endif
> >  int mana_rq_ring_doorbell(struct mana_rxq *rxq);
> >
> >  int gdma_post_work_request(struct mana_gdma_queue *queue, diff --git
> > a/drivers/net/mana/rx.c b/drivers/net/mana/rx.c index
> > 14d9085801..303d129e5b 100644
> > --- a/drivers/net/mana/rx.c
> > +++ b/drivers/net/mana/rx.c
> > @@ -39,10 +39,23 @@ mana_rq_ring_doorbell(struct mana_rxq *rxq)
> >  	/* Hardware Spec specifies that software client should set 0 for
> >  	 * wqe_cnt for Receive Queues.
> >  	 */
> > +#ifdef RTE_ARCH_32
> > +	if (rxq->wqe_cnt_to_short_db) {
> > +		ret = mana_ring_short_doorbell(db_page,
> > GDMA_QUEUE_RECEIVE,
> > +				 rxq->gdma_rq.id,
> > +				 rxq->wqe_cnt_to_short_db *
> > +
> > 	GDMA_WQE_ALIGNMENT_UNIT_SIZE,
> > +				 0);
> > +	} else {
> 
> Is it possible that rxq->wqe_cnt_to_short_db might be 0 from the caller? The
> caller shouldn't ring the doorbell if there is nothing to ring.
> 
This is just a safeguard. I can remove the check.
> 
> 
> 
> 
> > +		/* No need to ring, just return */
> > +		ret = 0;
> > +	}
> > +#else
> >  	ret = mana_ring_doorbell(db_page, GDMA_QUEUE_RECEIVE,
> >  			 rxq->gdma_rq.id,
> >  			 rxq->gdma_rq.head *
> > GDMA_WQE_ALIGNMENT_UNIT_SIZE,
> >  			 0);
> > +#endif
> >
> >  	if (ret)
> >  		DP_LOG(ERR, "failed to ring RX doorbell ret %d", ret); @@ -
> > 97,6 +110,7 @@ mana_alloc_and_post_rx_wqe(struct mana_rxq *rxq)
> >  		/* update queue for tracking pending packets */
> >  		desc->pkt = mbuf;
> >  		desc->wqe_size_in_bu = wqe_size_in_bu;
> > +		rxq->wqe_cnt_to_short_db += wqe_size_in_bu;
> >  		rxq->desc_ring_head = (rxq->desc_ring_head + 1) % rxq-
> > >num_desc;
> >  	} else {
> >  		DP_LOG(DEBUG, "failed to post recv ret %d", ret); @@ -
> > 115,12 +129,22 @@ mana_alloc_and_post_rx_wqes(struct mana_rxq *rxq)
> >  	int ret;
> >  	uint32_t i;
> >
> > +#ifdef RTE_ARCH_32
> > +	rxq->wqe_cnt_to_short_db = 0;
> > +#endif
> >  	for (i = 0; i < rxq->num_desc; i++) {
> >  		ret = mana_alloc_and_post_rx_wqe(rxq);
> >  		if (ret) {
> >  			DP_LOG(ERR, "failed to post RX ret = %d", ret);
> >  			return ret;
> >  		}
> > +
> > +#ifdef RTE_ARCH_32
> > +		if (rxq->wqe_cnt_to_short_db >
> > RX_WQE_SHORT_DB_THRESHOLD) {
> > +			mana_rq_ring_doorbell(rxq);
> > +			rxq->wqe_cnt_to_short_db = 0;
> > +		}
> > +#endif
> >  	}
> >
> >  	mana_rq_ring_doorbell(rxq);
> > @@ -349,6 +373,9 @@ mana_start_rx_queues(struct rte_eth_dev *dev)
> >
> >  		/* CQ head starts with count */
> >  		rxq->gdma_cq.head = rxq->gdma_cq.count;
> > +#ifdef RTE_ARCH_32
> > +		rxq->gdma_cq.head_incr_to_short_db = 0; #endif
> >
> >  		DRV_LOG(INFO, "rxq cq id %u buf %p count %u size %u",
> >  			rxq->gdma_cq.id, rxq->gdma_cq.buffer, @@ -397,6
> > +424,10 @@ mana_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts,
> > uint16_t pkts_n)
> >  	uint32_t i;
> >  	int polled = 0;
> >
> > +#ifdef RTE_ARCH_32
> > +	rxq->wqe_cnt_to_short_db = 0;
> > +#endif
> > +
> >  repoll:
> >  	/* Polling on new completions if we have no backlog */
> >  	if (rxq->comp_buf_idx == rxq->comp_buf_len) { @@ -505,6 +536,16
> @@
> > mana_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t
> > pkts_n)
> >  		wqe_posted++;
> >  		if (pkt_received == pkts_n)
> >  			break;
> > +
> > +#ifdef RTE_ARCH_32
> > +		/* Ring short doorbell if approaching the wqe increment
> > +		 * limit.
> > +		 */
> > +		if (rxq->wqe_cnt_to_short_db >
> > RX_WQE_SHORT_DB_THRESHOLD) {
> > +			mana_rq_ring_doorbell(rxq);
> > +			rxq->wqe_cnt_to_short_db = 0;
> > +		}
> > +#endif
> >  	}
> >
> >  	rxq->backlog_idx = pkt_idx;
> > @@ -529,6 +570,16 @@ static int
> >  mana_arm_cq(struct mana_rxq *rxq, uint8_t arm)  {
> >  	struct mana_priv *priv = rxq->priv;
> > +#ifdef RTE_ARCH_32
> > +	uint16_t cqe_incr = (uint16_t)rxq->gdma_cq.head_incr_to_short_db;
> 
> How do you make sure head_incr_to_short_db doesn't overflow?
> 

I have checked this with hardware team. In my opinion it would be easily overflown. 
The hw team seems suggesting the hw will take care of this.

Thanks,
Wei

> 
> Thanks,
> 
> Long