eth: bnxt: fix backward compatibility with older devices

Recent FW interface update bumped the size of struct hwrm_func_cfg_input
above 128B which is the max some devices support.

Probe on Stratus (BCM957452) with FW 20.8.3.11 fails with:

   bnxt_en ...: Unable to reserve tx rings
   bnxt_en ...: 2nd rings reservation failed.
   bnxt_en ...: Not enough rings available.

Once probe is fixed other errors pop up:

   bnxt_en ...: Failed to set async event completion ring.

This is because __hwrm_send() rejects requests larger than
bp->hwrm_max_ext_req_len with -E2BIG. Since the driver doesn't
actually access any of the new fields, yet, trim the length.
It should be safe.

Similar workaround exists for backing_store_cfg_input.
Although that one mins() to a constant of 256, not 128
we'll effectively use here. Michael explains: "the backing
store cfg command is supported by relatively newer firmware
that will accept 256 bytes at least."

To make debugging easier in the future add a warning
for oversized requests.

Fixes: 754fbf60 ("bnxt_en: Update firmware interface to 1.10.2.171")
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Link: https://lore.kernel.org/r/20231016171640.1481493-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -5861,7 +5861,7 @@ static int bnxt_hwrm_set_async_event_cr(struct bnxt *bp, int idx)
 	if (BNXT_PF(bp)) {
 		struct hwrm_func_cfg_input *req;
 
-		rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+		rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 		if (rc)
 			return rc;
 
@@ -6272,7 +6272,7 @@ __bnxt_hwrm_reserve_pf_rings(struct bnxt *bp, int tx_rings, int rx_rings,
 	struct hwrm_func_cfg_input *req;
 	u32 enables = 0;
 
-	if (hwrm_req_init(bp, req, HWRM_FUNC_CFG))
+	if (bnxt_hwrm_func_cfg_short_req_init(bp, &req))
 		return NULL;
 
 	req->fid = cpu_to_le16(0xffff);
@@ -8617,7 +8617,7 @@ static int bnxt_hwrm_set_br_mode(struct bnxt *bp, u16 br_mode)
 	else
 		return -EINVAL;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 
@@ -8635,7 +8635,7 @@ static int bnxt_hwrm_set_cache_line_size(struct bnxt *bp, int size)
 	if (BNXT_VF(bp) || bp->hwrm_spec_code < 0x10803)
 		return 0;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 

drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c

@@ -62,7 +62,7 @@ static int bnxt_hwrm_remote_dev_reset_set(struct bnxt *bp, bool remote_reset)
 	if (~bp->fw_cap & BNXT_FW_CAP_HOT_RESET_IF)
 		return -EOPNOTSUPP;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 

drivers/net/ethernet/broadcom/bnxt/bnxt_hwrm.c

@@ -485,6 +485,8 @@ static int __hwrm_send(struct bnxt *bp, struct bnxt_hwrm_ctx *ctx)
 
 	if (msg_len > BNXT_HWRM_MAX_REQ_LEN &&
 	    msg_len > bp->hwrm_max_ext_req_len) {
+		netdev_warn(bp->dev, "oversized hwrm request, req_type 0x%x",
+			    req_type);
 		rc = -E2BIG;
 		goto exit;
 	}

drivers/net/ethernet/broadcom/bnxt/bnxt_hwrm.h

@@ -137,4 +137,18 @@ int hwrm_req_send_silent(struct bnxt *bp, void *req);
 int hwrm_req_replace(struct bnxt *bp, void *req, void *new_req, u32 len);
 void hwrm_req_alloc_flags(struct bnxt *bp, void *req, gfp_t flags);
 void *hwrm_req_dma_slice(struct bnxt *bp, void *req, u32 size, dma_addr_t *dma);
+
+/* Older devices can only support req length of 128.
+ * HWRM_FUNC_CFG requests which don't need fields starting at
+ * num_quic_tx_key_ctxs can use this helper to avoid getting -E2BIG.
+ */
+static inline int
+bnxt_hwrm_func_cfg_short_req_init(struct bnxt *bp,
+				  struct hwrm_func_cfg_input **req)
+{
+	u32 req_len;
+
+	req_len = min_t(u32, sizeof(**req), bp->hwrm_max_ext_req_len);
+	return __hwrm_req_init(bp, (void **)req, HWRM_FUNC_CFG, req_len);
+}
 #endif

drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c

@@ -95,7 +95,7 @@ int bnxt_set_vf_spoofchk(struct net_device *dev, int vf_id, bool setting)
 	/*TODO: if the driver supports VLAN filter on guest VLAN,
 	 * the spoof check should also include vlan anti-spoofing
 	 */
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (!rc) {
 		req->fid = cpu_to_le16(vf->fw_fid);
 		req->flags = cpu_to_le32(func_flags);
@@ -146,7 +146,7 @@ static int bnxt_hwrm_set_trusted_vf(struct bnxt *bp, struct bnxt_vf_info *vf)
 	if (!(bp->fw_cap & BNXT_FW_CAP_TRUSTED_VF))
 		return 0;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 
@@ -232,7 +232,7 @@ int bnxt_set_vf_mac(struct net_device *dev, int vf_id, u8 *mac)
 	}
 	vf = &bp->pf.vf[vf_id];
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 
@@ -274,7 +274,7 @@ int bnxt_set_vf_vlan(struct net_device *dev, int vf_id, u16 vlan_id, u8 qos,
 	if (vlan_tag == vf->vlan)
 		return 0;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (!rc) {
 		req->fid = cpu_to_le16(vf->fw_fid);
 		req->dflt_vlan = cpu_to_le16(vlan_tag);
@@ -314,7 +314,7 @@ int bnxt_set_vf_bw(struct net_device *dev, int vf_id, int min_tx_rate,
 	}
 	if (min_tx_rate == vf->min_tx_rate && max_tx_rate == vf->max_tx_rate)
 		return 0;
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (!rc) {
 		req->fid = cpu_to_le16(vf->fw_fid);
 		req->enables = cpu_to_le32(FUNC_CFG_REQ_ENABLES_MAX_BW |
@@ -491,7 +491,7 @@ static int __bnxt_set_vf_params(struct bnxt *bp, int vf_id)
 	struct bnxt_vf_info *vf;
 	int rc;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;
 
@@ -653,7 +653,7 @@ static int bnxt_hwrm_func_cfg(struct bnxt *bp, int num_vfs)
 	u32 mtu, i;
 	int rc;
 
-	rc = hwrm_req_init(bp, req, HWRM_FUNC_CFG);
+	rc = bnxt_hwrm_func_cfg_short_req_init(bp, &req);
 	if (rc)
 		return rc;