Author: mw
Date: Thu May 30 13:18:23 2019
New Revision: 348394
URL: https://svnweb.freebsd.org/changeset/base/348394

Log:
  Fix DMA synchronization in the ENA driver Tx and Rx paths
  
  The DMA in FreeBSD requires explicit synchronization. ENA driver was
  only doing PREREAD and PREWRITE synchronizations. Missing
  bus_dmamap_sync() calls were added.
  
  It is also required to synchronize DMA engine before unloading DMA map.
  
  Submitted by:  Michal Krawczyk <m...@semihalf.com>
  Obtained from: Semihalf
  Sponsored by:  Amazon, Inc.

Modified:
  head/sys/dev/ena/ena.c

Modified: head/sys/dev/ena/ena.c
==============================================================================
--- head/sys/dev/ena/ena.c      Thu May 30 13:16:56 2019        (r348393)
+++ head/sys/dev/ena/ena.c      Thu May 30 13:18:23 2019        (r348394)
@@ -268,6 +268,9 @@ ena_dma_alloc(device_t dmadev, bus_size_t size,
                goto fail_map_load;
        }
 
+       bus_dmamap_sync(dma->tag, dma->map,
+           BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
+
        return (0);
 
 fail_map_load:
@@ -678,12 +681,14 @@ ena_free_tx_resources(struct ena_adapter *adapter, int
 
        /* Free buffer DMA maps, */
        for (int i = 0; i < tx_ring->ring_size; i++) {
-               m_freem(tx_ring->tx_buffer_info[i].mbuf);
-               tx_ring->tx_buffer_info[i].mbuf = NULL;
+               bus_dmamap_sync(adapter->tx_buf_tag,
+                   tx_ring->tx_buffer_info[i].map, BUS_DMASYNC_POSTWRITE);
                bus_dmamap_unload(adapter->tx_buf_tag,
                    tx_ring->tx_buffer_info[i].map);
                bus_dmamap_destroy(adapter->tx_buf_tag,
                    tx_ring->tx_buffer_info[i].map);
+               m_freem(tx_ring->tx_buffer_info[i].mbuf);
+               tx_ring->tx_buffer_info[i].mbuf = NULL;
        }
        ENA_RING_MTX_UNLOCK(tx_ring);
 
@@ -859,6 +864,8 @@ ena_free_rx_resources(struct ena_adapter *adapter, uns
 
        /* Free buffer DMA maps, */
        for (int i = 0; i < rx_ring->ring_size; i++) {
+               bus_dmamap_sync(adapter->rx_buf_tag,
+                   rx_ring->rx_buffer_info[i].map, BUS_DMASYNC_POSTREAD);
                m_freem(rx_ring->rx_buffer_info[i].mbuf);
                rx_ring->rx_buffer_info[i].mbuf = NULL;
                bus_dmamap_unload(adapter->rx_buf_tag,
@@ -993,6 +1000,8 @@ ena_free_rx_mbuf(struct ena_adapter *adapter, struct e
                return;
        }
 
+       bus_dmamap_sync(adapter->rx_buf_tag, rx_info->map,
+           BUS_DMASYNC_POSTREAD);
        bus_dmamap_unload(adapter->rx_buf_tag, rx_info->map);
        m_freem(rx_info->mbuf);
        rx_info->mbuf = NULL;
@@ -1134,6 +1143,8 @@ ena_free_tx_bufs(struct ena_adapter *adapter, unsigned
                             qid, i);
                }
 
+               bus_dmamap_sync(adapter->tx_buf_tag, tx_info->map,
+                   BUS_DMASYNC_POSTWRITE);
                bus_dmamap_unload(adapter->tx_buf_tag, tx_info->map);
                m_free(tx_info->mbuf);
                tx_info->mbuf = NULL;
@@ -1334,6 +1345,8 @@ ena_tx_cleanup(struct ena_ring *tx_ring)
 
                if (likely(tx_info->num_of_bufs != 0)) {
                        /* Map is no longer required */
+                       bus_dmamap_sync(adapter->tx_buf_tag, tx_info->map,
+                           BUS_DMASYNC_POSTWRITE);
                        bus_dmamap_unload(adapter->tx_buf_tag, tx_info->map);
                }
 
@@ -1467,6 +1480,8 @@ ena_rx_mbuf(struct ena_ring *rx_ring, struct ena_com_r
        ena_trace(ENA_DBG | ENA_RXPTH, "rx_info %p, mbuf %p, paddr %jx",
            rx_info, rx_info->mbuf, (uintmax_t)rx_info->ena_buf.paddr);
 
+       bus_dmamap_sync(adapter->rx_buf_tag, rx_info->map,
+           BUS_DMASYNC_POSTREAD);
        mbuf = rx_info->mbuf;
        mbuf->m_flags |= M_PKTHDR;
        mbuf->m_pkthdr.len = len;
@@ -1522,6 +1537,8 @@ ena_rx_mbuf(struct ena_ring *rx_ring, struct ena_com_r
                        return (NULL);
                }
 
+               bus_dmamap_sync(adapter->rx_buf_tag, rx_info->map,
+                   BUS_DMASYNC_POSTREAD);
                if (unlikely(m_append(mbuf, len, rx_info->mbuf->m_data) == 0)) {
                        counter_u64_add(rx_ring->rx_stats.mbuf_alloc_fail, 1);
                        ena_trace(ENA_WARNING, "Failed to append Rx mbuf %p",
@@ -1632,6 +1649,8 @@ ena_rx_cleanup(struct ena_ring *rx_ring)
                ena_rx_ctx.ena_bufs = rx_ring->ena_bufs;
                ena_rx_ctx.max_bufs = adapter->max_rx_sgl_size;
                ena_rx_ctx.descs = 0;
+               bus_dmamap_sync(io_cq->cdesc_addr.mem_handle.tag,
+                   io_cq->cdesc_addr.mem_handle.map, BUS_DMASYNC_POSTREAD);
                rc = ena_com_rx_pkt(io_cq, io_sq, &ena_rx_ctx);
 
                if (unlikely(rc != 0))
@@ -1648,7 +1667,8 @@ ena_rx_cleanup(struct ena_ring *rx_ring)
                /* Receive mbuf from the ring */
                mbuf = ena_rx_mbuf(rx_ring, rx_ring->ena_bufs,
                    &ena_rx_ctx, &next_to_clean);
-
+               bus_dmamap_sync(io_cq->cdesc_addr.mem_handle.tag,
+                   io_cq->cdesc_addr.mem_handle.map, BUS_DMASYNC_PREREAD);
                /* Exit if we failed to retrieve a buffer */
                if (unlikely(mbuf == NULL)) {
                        for (i = 0; i < ena_rx_ctx.descs; ++i) {
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