Issue #4308042: Fix read of invalid data from CQE

According to the PRM - section 8.20.3.2:
"After seeing that the CQE is in SW ownership,
SW should do memory barrier and re-read the CQE."

It was removed as part of commit 88436b2 -
causing us to sometimes observe “garbage” data.

This commit returns the barrier as needed.

Signed-off-by: Tomer Cabouly <[email protected]>

Author: tomerdbz

src/core/dev/cq_mgr_rx_regrq.cpp

@@ -107,6 +107,7 @@ mem_buf_desc_t *cq_mgr_rx_regrq::poll(enum buff_status_e &status)
     xlio_mlx5_cqe *cqe = check_cqe();
     if (likely(cqe)) {
         ++m_mlx5_cq.cq_ci;
+        rmb();
         cqe_to_mem_buff_desc(cqe, m_rx_hot_buffer, status);
 
         ++m_hqrx_ptr->m_rq_data.tail;

src/core/dev/cq_mgr_rx_strq.cpp

@@ -188,6 +188,7 @@ mem_buf_desc_t *cq_mgr_rx_strq::poll(enum buff_status_e &status, mem_buf_desc_t
     xlio_mlx5_cqe *cqe = check_cqe();
     if (likely(cqe)) {
         ++m_mlx5_cq.cq_ci;
+        rmb();
 
         bool is_filler = false;
         bool is_wqe_complete = strq_cqe_to_mem_buff_desc(cqe, status, is_filler);

src/core/dev/cq_mgr_tx.h

@@ -144,6 +144,9 @@ inline struct xlio_mlx5_cqe *cq_mgr_tx::get_cqe_tx(uint32_t &num_polled_cqes)
                                        ((m_mlx5_cq.cq_ci & (m_mlx5_cq.cqe_count - 1))
                                         << m_mlx5_cq.cqe_size_log));
     }
+    if (cqe_ret) {
+        rmb();
+    }
     return cqe_ret;
 }
 

src/core/dev/ring_slave.cpp

@@ -739,8 +739,9 @@ bool ring_slave::rx_process_buffer(mem_buf_desc_t *p_rx_wc_buf_desc, void *pv_fd
 
         // Validate IP header as next protocol
         if (unlikely(h_proto != NET_ETH_P_IP) && unlikely(h_proto != NET_ETH_P_IPV6)) {
-            ring_logwarn("Rx buffer dropped - Invalid Ethr Type (%#x : %#x, %#x)", p_eth_h->h_proto,
-                         NET_ETH_P_IP, NET_ETH_P_IPV6);
+            ring_logwarn("Rx buffer dropped - Invalid Ethr Type (h_proto=%#x-p_eth_h->h_proto=%#x "
+                         ": %#x, %#x)",
+                         h_proto, p_eth_h->h_proto, NET_ETH_P_IP, NET_ETH_P_IPV6);
             return false;
         }
     } break;