[PATCH v4 12/31] net/ena/base: add completion descriptor corruption check

[<shaibran@amazon.com>]

From: Shai Brandes <shaibran@amazon.com>

Adding a check of the MBZ (Must Be Zero) fields in the
incoming tx and rx completion descriptors in order to
identify corrupted descriptors.

Signed-off-by: Shai Brandes <shaibran@amazon.com>
Reviewed-by: Amit Bernstein <amitbern@amazon.com>
---
 drivers/net/ena/base/ena_eth_com.c | 13 +++++++++++--
 drivers/net/ena/base/ena_eth_com.h | 14 +++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ena/base/ena_eth_com.c b/drivers/net/ena/base/ena_eth_com.c
index 875d55b00d..58d1cc68d9 100644
--- a/drivers/net/ena/base/ena_eth_com.c
+++ b/drivers/net/ena/base/ena_eth_com.c
@@ -236,6 +236,7 @@ static int ena_com_cdesc_rx_pkt_get(struct ena_com_io_cq *io_cq,
 				    u16 *first_cdesc_idx,
 				    u16 *num_descs)
 {
+	struct ena_com_dev *dev = ena_com_io_cq_to_ena_dev(io_cq);
 	u16 count = io_cq->cur_rx_pkt_cdesc_count, head_masked;
 	struct ena_eth_io_rx_cdesc_base *cdesc;
 	u32 last = 0;
@@ -251,13 +252,21 @@ static int ena_com_cdesc_rx_pkt_get(struct ena_com_io_cq *io_cq,
 		ena_com_cq_inc_head(io_cq);
 		if (unlikely((status & ENA_ETH_IO_RX_CDESC_BASE_FIRST_MASK) >>
 		    ENA_ETH_IO_RX_CDESC_BASE_FIRST_SHIFT && count != 0)) {
-			struct ena_com_dev *dev = ena_com_io_cq_to_ena_dev(io_cq);
-
 			ena_trc_err(dev,
 				    "First bit is on in descriptor #%d on q_id: %d, req_id: %u\n",
 				    count, io_cq->qid, cdesc->req_id);
 			return ENA_COM_FAULT;
 		}
+
+		if (unlikely((status & (ENA_ETH_IO_RX_CDESC_BASE_MBZ7_MASK |
+					ENA_ETH_IO_RX_CDESC_BASE_MBZ17_MASK)) &&
+			      ena_com_get_cap(dev, ENA_ADMIN_CDESC_MBZ))) {
+			ena_trc_err(dev,
+				    "Corrupted RX descriptor #%d on q_id: %d, req_id: %u\n",
+				    count, io_cq->qid, cdesc->req_id);
+			return ENA_COM_FAULT;
+		}
+
 		count++;
 		last = (status & ENA_ETH_IO_RX_CDESC_BASE_LAST_MASK) >>
 			ENA_ETH_IO_RX_CDESC_BASE_LAST_SHIFT;
diff --git a/drivers/net/ena/base/ena_eth_com.h b/drivers/net/ena/base/ena_eth_com.h
index 6a7c17f84f..2fac10e678 100644
--- a/drivers/net/ena/base/ena_eth_com.h
+++ b/drivers/net/ena/base/ena_eth_com.h
@@ -204,9 +204,11 @@ static inline void ena_com_cq_inc_head(struct ena_com_io_cq *io_cq)
 static inline int ena_com_tx_comp_req_id_get(struct ena_com_io_cq *io_cq,
 					     u16 *req_id)
 {
+	struct ena_com_dev *dev = ena_com_io_cq_to_ena_dev(io_cq);
 	u8 expected_phase, cdesc_phase;
 	struct ena_eth_io_tx_cdesc *cdesc;
 	u16 masked_head;
+	u8 flags;
 
 	masked_head = io_cq->head & (io_cq->q_depth - 1);
 	expected_phase = io_cq->phase;
@@ -215,14 +217,24 @@ static inline int ena_com_tx_comp_req_id_get(struct ena_com_io_cq *io_cq,
 		((uintptr_t)io_cq->cdesc_addr.virt_addr +
 		(masked_head * io_cq->cdesc_entry_size_in_bytes));
 
+	flags = READ_ONCE8(cdesc->flags);
+
 	/* When the current completion descriptor phase isn't the same as the
 	 * expected, it mean that the device still didn't update
 	 * this completion.
 	 */
-	cdesc_phase = READ_ONCE8(cdesc->flags) & ENA_ETH_IO_TX_CDESC_PHASE_MASK;
+	cdesc_phase = flags & ENA_ETH_IO_TX_CDESC_PHASE_MASK;
 	if (cdesc_phase != expected_phase)
 		return ENA_COM_TRY_AGAIN;
 
+	if (unlikely((flags & ENA_ETH_IO_TX_CDESC_MBZ6_MASK) &&
+		      ena_com_get_cap(dev, ENA_ADMIN_CDESC_MBZ))) {
+		ena_trc_err(dev,
+			    "Corrupted TX descriptor on q_id: %d, req_id: %u\n",
+			    io_cq->qid, cdesc->req_id);
+		return ENA_COM_FAULT;
+	}
+
 	dma_rmb();
 
 	*req_id = READ_ONCE16(cdesc->req_id);
-- 
2.17.1