[PATCH net-next 10/16] bnxt_en: Improve valid bit checking in firmware response message.

[Michael Chan <michael.chan@broadcom.com>]

When firmware sends a DMA response to the driver, the last byte of the
message will be set to 1 to indicate that the whole response is valid.
The driver waits for the message to be valid before reading the message.

The firmware spec allows these response messages to increase in
length by adding new fields to the end of these messages.  The
older spec's valid location may become a new field in a newer
spec.  To guarantee compatibility, the driver should zero the valid
byte before interpreting the entire message so that any new fields not
implemented by the older spec will be read as zero.

For messages that are forwarded to VFs, we need to set the length
and re-instate the valid bit so the VF will see the valid response.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c       | 21 ++++++++++++++++-----
 drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c |  2 ++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 62b7d69c..6fcf4dc 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -3422,7 +3422,8 @@ static int bnxt_hwrm_do_send_msg(struct bnxt *bp, void *msg, u32 msg_len,
 	int i, intr_process, rc, tmo_count;
 	struct input *req = msg;
 	u32 *data = msg;
-	__le32 *resp_len, *valid;
+	__le32 *resp_len;
+	u8 *valid;
 	u16 cp_ring_id, len = 0;
 	struct hwrm_err_output *resp = bp->hwrm_cmd_resp_addr;
 	u16 max_req_len = BNXT_HWRM_MAX_REQ_LEN;
@@ -3474,6 +3475,7 @@ static int bnxt_hwrm_do_send_msg(struct bnxt *bp, void *msg, u32 msg_len,
 
 	i = 0;
 	tmo_count = timeout * 40;
+	resp_len = bp->hwrm_cmd_resp_addr + HWRM_RESP_LEN_OFFSET;
 	if (intr_process) {
 		/* Wait until hwrm response cmpl interrupt is processed */
 		while (bp->hwrm_intr_seq_id != HWRM_SEQ_ID_INVALID &&
@@ -3486,9 +3488,11 @@ static int bnxt_hwrm_do_send_msg(struct bnxt *bp, void *msg, u32 msg_len,
 				   le16_to_cpu(req->req_type));
 			return -1;
 		}
+		len = (le32_to_cpu(*resp_len) & HWRM_RESP_LEN_MASK) >>
+		      HWRM_RESP_LEN_SFT;
+		valid = bp->hwrm_cmd_resp_addr + len - 1;
 	} else {
 		/* Check if response len is updated */
-		resp_len = bp->hwrm_cmd_resp_addr + HWRM_RESP_LEN_OFFSET;
 		for (i = 0; i < tmo_count; i++) {
 			len = (le32_to_cpu(*resp_len) & HWRM_RESP_LEN_MASK) >>
 			      HWRM_RESP_LEN_SFT;
@@ -3504,10 +3508,12 @@ static int bnxt_hwrm_do_send_msg(struct bnxt *bp, void *msg, u32 msg_len,
 			return -1;
 		}
 
-		/* Last word of resp contains valid bit */
-		valid = bp->hwrm_cmd_resp_addr + len - 4;
+		/* Last byte of resp contains valid bit */
+		valid = bp->hwrm_cmd_resp_addr + len - 1;
 		for (i = 0; i < 5; i++) {
-			if (le32_to_cpu(*valid) & HWRM_RESP_VALID_MASK)
+			/* make sure we read from updated DMA memory */
+			dma_rmb();
+			if (*valid)
 				break;
 			udelay(1);
 		}
@@ -3520,6 +3526,11 @@ static int bnxt_hwrm_do_send_msg(struct bnxt *bp, void *msg, u32 msg_len,
 		}
 	}
 
+	/* Zero valid bit for compatibility.  Valid bit in an older spec
+	 * may become a new field in a newer spec.  We must make sure that
+	 * a new field not implemented by old spec will read zero.
+	 */
+	*valid = 0;
 	rc = le16_to_cpu(resp->error_code);
 	if (rc && !silent)
 		netdev_err(bp->dev, "hwrm req_type 0x%x seq id 0x%x error 0x%x\n",
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
index 4fa4761..f952963 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
@@ -974,7 +974,9 @@ static int bnxt_vf_set_link(struct bnxt *bp, struct bnxt_vf_info *vf)
 		memcpy(&phy_qcfg_resp, &bp->link_info.phy_qcfg_resp,
 		       sizeof(phy_qcfg_resp));
 		mutex_unlock(&bp->hwrm_cmd_lock);
+		phy_qcfg_resp.resp_len = cpu_to_le16(sizeof(phy_qcfg_resp));
 		phy_qcfg_resp.seq_id = phy_qcfg_req->seq_id;
+		phy_qcfg_resp.valid = 1;
 
 		if (vf->flags & BNXT_VF_LINK_UP) {
 			/* if physical link is down, force link up on VF */
-- 
1.8.3.1