net/sfc: calculate Rx buffer size which may be used

Take Rx buffer start alignment and end-padding into account.

Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@solarflare.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/drivers/net/sfc/sfc_rx.c b/drivers/net/sfc/sfc_rx.c
index 00bcc9d..0a37776 100644 (file)
--- a/drivers/net/sfc/sfc_rx.c
+++ b/drivers/net/sfc/sfc_rx.c
@@ -66,6 +66,106 @@ sfc_rx_qcheck_conf(struct sfc_adapter *sa,
        return rc;
 }
 
+static unsigned int
+sfc_rx_mbuf_data_alignment(struct rte_mempool *mb_pool)
+{
+       uint32_t data_off;
+       uint32_t order;
+
+       /* The mbuf object itself is always cache line aligned */
+       order = rte_bsf32(RTE_CACHE_LINE_SIZE);
+
+       /* Data offset from mbuf object start */
+       data_off = sizeof(struct rte_mbuf) + rte_pktmbuf_priv_size(mb_pool) +
+               RTE_PKTMBUF_HEADROOM;
+
+       order = MIN(order, rte_bsf32(data_off));
+
+       return 1u << (order - 1);
+}
+
+static uint16_t
+sfc_rx_mb_pool_buf_size(struct sfc_adapter *sa, struct rte_mempool *mb_pool)
+{
+       const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
+       const uint32_t nic_align_start = MAX(1, encp->enc_rx_buf_align_start);
+       const uint32_t nic_align_end = MAX(1, encp->enc_rx_buf_align_end);
+       uint16_t buf_size;
+       unsigned int buf_aligned;
+       unsigned int start_alignment;
+       unsigned int end_padding_alignment;
+
+       /* Below it is assumed that both alignments are power of 2 */
+       SFC_ASSERT(rte_is_power_of_2(nic_align_start));
+       SFC_ASSERT(rte_is_power_of_2(nic_align_end));
+
+       /*
+        * mbuf is always cache line aligned, double-check
+        * that it meets rx buffer start alignment requirements.
+        */
+
+       /* Start from mbuf pool data room size */
+       buf_size = rte_pktmbuf_data_room_size(mb_pool);
+
+       /* Remove headroom */
+       if (buf_size <= RTE_PKTMBUF_HEADROOM) {
+               sfc_err(sa,
+                       "RxQ mbuf pool %s object data room size %u is smaller than headroom %u",
+                       mb_pool->name, buf_size, RTE_PKTMBUF_HEADROOM);
+               return 0;
+       }
+       buf_size -= RTE_PKTMBUF_HEADROOM;
+
+       /* Calculate guaranteed data start alignment */
+       buf_aligned = sfc_rx_mbuf_data_alignment(mb_pool);
+
+       /* Reserve space for start alignment */
+       if (buf_aligned < nic_align_start) {
+               start_alignment = nic_align_start - buf_aligned;
+               if (buf_size <= start_alignment) {
+                       sfc_err(sa,
+                               "RxQ mbuf pool %s object data room size %u is insufficient for headroom %u and buffer start alignment %u required by NIC",
+                               mb_pool->name,
+                               rte_pktmbuf_data_room_size(mb_pool),
+                               RTE_PKTMBUF_HEADROOM, start_alignment);
+                       return 0;
+               }
+               buf_aligned = nic_align_start;
+               buf_size -= start_alignment;
+       } else {
+               start_alignment = 0;
+       }
+
+       /* Make sure that end padding does not write beyond the buffer */
+       if (buf_aligned < nic_align_end) {
+               /*
+                * Estimate space which can be lost. If guarnteed buffer
+                * size is odd, lost space is (nic_align_end - 1). More
+                * accurate formula is below.
+                */
+               end_padding_alignment = nic_align_end -
+                       MIN(buf_aligned, 1u << (rte_bsf32(buf_size) - 1));
+               if (buf_size <= end_padding_alignment) {
+                       sfc_err(sa,
+                               "RxQ mbuf pool %s object data room size %u is insufficient for headroom %u, buffer start alignment %u and end padding alignment %u required by NIC",
+                               mb_pool->name,
+                               rte_pktmbuf_data_room_size(mb_pool),
+                               RTE_PKTMBUF_HEADROOM, start_alignment,
+                               end_padding_alignment);
+                       return 0;
+               }
+               buf_size -= end_padding_alignment;
+       } else {
+               /*
+                * Start is aligned the same or better than end,
+                * just align length.
+                */
+               buf_size = P2ALIGN(buf_size, nic_align_end);
+       }
+
+       return buf_size;
+}
+
 int
 sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
             uint16_t nb_rx_desc, unsigned int socket_id,
@@ -73,6 +173,7 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
             struct rte_mempool *mb_pool)
 {
        int rc;
+       uint16_t buf_size;
        struct sfc_rxq_info *rxq_info;
        unsigned int evq_index;
        struct sfc_evq *evq;
@@ -82,10 +183,10 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
        if (rc != 0)
                goto fail_bad_conf;
 
-       if (rte_pktmbuf_data_room_size(mb_pool) <= RTE_PKTMBUF_HEADROOM) {
-               sfc_err(sa, "RxQ %u mbuf is too small, %u vs headroom %u",
-                       sw_index, rte_pktmbuf_data_room_size(mb_pool),
-                       RTE_PKTMBUF_HEADROOM);
+       buf_size = sfc_rx_mb_pool_buf_size(sa, mb_pool);
+       if (buf_size == 0) {
+               sfc_err(sa, "RxQ %u mbuf pool object size is too small",
+                       sw_index);
                goto fail_bad_conf;
        }
 
@@ -126,6 +227,7 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
        rxq->evq = evq;
        rxq->ptr_mask = rxq_info->entries - 1;
        rxq->refill_mb_pool = mb_pool;
+       rxq->buf_size = buf_size;
        rxq->hw_index = sw_index;
 
        rxq->state = SFC_RXQ_INITIALIZED;

diff --git a/drivers/net/sfc/sfc_rx.h b/drivers/net/sfc/sfc_rx.h
index b506d9a..9719eae 100644 (file)
--- a/drivers/net/sfc/sfc_rx.h
+++ b/drivers/net/sfc/sfc_rx.h
@@ -71,6 +71,7 @@ struct sfc_rxq {
        unsigned int            ptr_mask;
 
        /* Used on refill */
+       uint16_t                buf_size;
        struct rte_mempool      *refill_mb_pool;
        efx_rxq_t               *common;
        efsys_mem_t             mem;