[dpdk-dev] [PATCH v4 15/16] fm10k: fix a crash issue in vector RX func

["Chen Jing D(Mark)" <jing.d.chen@intel.com>]

From: "Chen Jing D(Mark)" <jing.d.chen@intel.com>

Vector RX function will process 4 packets at a time. When the RX
ring wrapps to the tail and the left descriptor size is not multiple
of 4, SW will overwrite memory that not belongs to it and cause crash.
The fix will allocate additional 4 HW/SW spaces at the tail to avoid
overwrite.

Signed-off-by: Chen Jing D(Mark) <jing.d.chen@intel.com>
---
 drivers/net/fm10k/fm10k.h        |    4 +++-
 drivers/net/fm10k/fm10k_ethdev.c |   19 +++++++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/net/fm10k/fm10k.h b/drivers/net/fm10k/fm10k.h
index 8e2c6a4..82a548f 100644
--- a/drivers/net/fm10k/fm10k.h
+++ b/drivers/net/fm10k/fm10k.h
@@ -177,7 +177,7 @@ struct fm10k_rx_queue {
 	struct rte_mbuf *pkt_last_seg;  /* Last segment of current packet. */
 	uint64_t hw_ring_phys_addr;
 	uint64_t mbuf_initializer; /* value to init mbufs */
-	/** need to alloc dummy mbuf, for wraparound when scanning hw ring */
+	/* need to alloc dummy mbuf, for wraparound when scanning hw ring */
 	struct rte_mbuf fake_mbuf;
 	uint16_t next_dd;
 	uint16_t next_alloc;
@@ -185,6 +185,8 @@ struct fm10k_rx_queue {
 	uint16_t alloc_thresh;
 	volatile uint32_t *tail_ptr;
 	uint16_t nb_desc;
+	/* Number of faked desc added at the tail for Vector RX function */
+	uint16_t nb_fake_desc;
 	uint16_t queue_id;
 	/* Below 2 fields only valid in case vPMD is applied. */
 	uint16_t rxrearm_nb;     /* number of remaining to be re-armed */
diff --git a/drivers/net/fm10k/fm10k_ethdev.c b/drivers/net/fm10k/fm10k_ethdev.c
index 469bd85..705b311 100644
--- a/drivers/net/fm10k/fm10k_ethdev.c
+++ b/drivers/net/fm10k/fm10k_ethdev.c
@@ -102,6 +102,7 @@ fm10k_mbx_unlock(struct fm10k_hw *hw)
 static inline int
 rx_queue_reset(struct fm10k_rx_queue *q)
 {
+	static const union fm10k_rx_desc zero = {{0} };
 	uint64_t dma_addr;
 	int i, diag;
 	PMD_INIT_FUNC_TRACE();
@@ -122,6 +123,15 @@ rx_queue_reset(struct fm10k_rx_queue *q)
 		q->hw_ring[i].q.hdr_addr = dma_addr;
 	}
 
+	/* initialize extra software ring entries. Space for these extra
+	 * entries is always allocated.
+	 */
+	memset(&q->fake_mbuf, 0x0, sizeof(q->fake_mbuf));
+	for (i = 0; i < q->nb_fake_desc; ++i) {
+		q->sw_ring[q->nb_desc + i] = &q->fake_mbuf;
+		q->hw_ring[q->nb_desc + i] = zero;
+	}
+
 	q->next_dd = 0;
 	q->next_alloc = 0;
 	q->next_trigger = q->alloc_thresh - 1;
@@ -147,6 +157,10 @@ rx_queue_clean(struct fm10k_rx_queue *q)
 	for (i = 0; i < q->nb_desc; ++i)
 		q->hw_ring[i] = zero;
 
+	/* zero faked descriptors */
+	for (i = 0; i < q->nb_fake_desc; ++i)
+		q->hw_ring[q->nb_desc + i] = zero;
+
 	/* vPMD driver has a different way of releasing mbufs. */
 	if (q->rx_using_sse) {
 		fm10k_rx_queue_release_mbufs_vec(q);
@@ -1323,6 +1337,7 @@ fm10k_rx_queue_setup(struct rte_eth_dev *dev, uint16_t queue_id,
 	/* setup queue */
 	q->mp = mp;
 	q->nb_desc = nb_desc;
+	q->nb_fake_desc = FM10K_MULT_RX_DESC;
 	q->port_id = dev->data->port_id;
 	q->queue_id = queue_id;
 	q->tail_ptr = (volatile uint32_t *)
@@ -1332,8 +1347,8 @@ fm10k_rx_queue_setup(struct rte_eth_dev *dev, uint16_t queue_id,
 
 	/* allocate memory for the software ring */
 	q->sw_ring = rte_zmalloc_socket("fm10k sw ring",
-					nb_desc * sizeof(struct rte_mbuf *),
-					RTE_CACHE_LINE_SIZE, socket_id);
+			(nb_desc + q->nb_fake_desc) * sizeof(struct rte_mbuf *),
+			RTE_CACHE_LINE_SIZE, socket_id);
 	if (q->sw_ring == NULL) {
 		PMD_INIT_LOG(ERR, "Cannot allocate software ring");
 		rte_free(q);
-- 
1.7.7.6