scsi: qla2xxx: Handle cases for limiting RDP response payload length

This patch reduces RDP response payload length, if requesting port is a
domain controller (sid 0xfffc01) and fw is earlier than 8.09.00 and fw is
not 8.05.65 then limit the RDP response payload length to maximum of 256
bytes by terminating the response just before the optical element
descriptor.

Link: https://lore.kernel.org/r/20200212214436.25532-15-hmadhani@marvell.com
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Joe Carnuccio <joe.carnuccio@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -5769,6 +5769,32 @@ retry_lock:
 	return;
 }
 
+static bool
+qla25xx_rdp_rsp_reduce_size(struct scsi_qla_host *vha,
+	struct purex_entry_24xx *purex)
+{
+	char fwstr[16];
+	u32 sid = purex->s_id[2] << 16 | purex->s_id[1] << 8 | purex->s_id[0];
+
+	/* Domain Controller is always logged-out. */
+	/* if RDP request is not from Domain Controller: */
+	if (sid != 0xfffc01)
+		return false;
+
+	ql_dbg(ql_dbg_init, vha, 0x0181, "%s: s_id=%#x\n", __func__, sid);
+
+	vha->hw->isp_ops->fw_version_str(vha, fwstr, sizeof(fwstr));
+	fwstr[strcspn(fwstr, " ")] = 0;
+	/* if FW version allows RDP response length upto 2048 bytes: */
+	if (strcmp(fwstr, "8.09.00") > 0 || strcmp(fwstr, "8.05.65") == 0)
+		return false;
+
+	ql_dbg(ql_dbg_init, vha, 0x0181, "%s: fw=%s\n", __func__, fwstr);
+
+	/* RDP response length is to be reduced to maximum 256 bytes */
+	return true;
+}
+
 static uint
 qla25xx_rdp_port_speed_capability(struct qla_hw_data *ha)
 {
@@ -5887,6 +5913,7 @@ void qla24xx_process_purex_rdp(struct scsi_qla_host *vha, void *pkt)
 	struct buffer_credit_24xx *bbc = NULL;
 	uint8_t *sfp = NULL;
 	uint16_t sfp_flags = 0;
+	uint rsp_payload_length = sizeof(*rsp_payload);
 	int rval;
 
 	ql_dbg(ql_dbg_init + ql_dbg_verbose, vha, 0x0180,
@@ -5897,6 +5924,14 @@ void qla24xx_process_purex_rdp(struct scsi_qla_host *vha, void *pkt)
 	ql_dump_buffer(ql_dbg_init + ql_dbg_verbose, vha, 0x0182,
 	    (void *)purex, sizeof(*purex));
 
+	if (qla25xx_rdp_rsp_reduce_size(vha, purex)) {
+		rsp_payload_length =
+		    offsetof(typeof(*rsp_payload), optical_elmt_desc);
+		ql_dbg(ql_dbg_init, vha, 0x0181,
+		    "Reducing RSP payload length to %u bytes...\n",
+		    rsp_payload_length);
+	}
+
 	rsp_els = dma_alloc_coherent(&ha->pdev->dev, sizeof(*rsp_els),
 	    &rsp_els_dma, GFP_KERNEL);
 	if (!rsp_els) {
@@ -5943,7 +5978,7 @@ void qla24xx_process_purex_rdp(struct scsi_qla_host *vha, void *pkt)
 
 	rsp_els->control_flags = EPD_ELS_ACC;
 	rsp_els->rx_byte_count = 0;
-	rsp_els->tx_byte_count = cpu_to_le32(sizeof(*rsp_payload));
+	rsp_els->tx_byte_count = cpu_to_le32(rsp_payload_length);
 
 	put_unaligned_le64(rsp_payload_dma, &rsp_els->tx_address);
 	rsp_els->tx_len = rsp_els->tx_byte_count;
@@ -6118,6 +6153,9 @@ accept:
 		}
 	}
 
+	if (rsp_payload_length < sizeof(*rsp_payload))
+		goto send;
+
 	if (sfp) {
 		memset(sfp, 0, SFP_RTDI_LEN);
 		rval = qla2x00_read_sfp(vha, sfp_dma, sfp, 0xa2, 0, 64, 0);
@@ -6278,7 +6316,7 @@ send:
 	ql_dbg(ql_dbg_init + ql_dbg_verbose, vha, 0x0186,
 	    "-------- ELS RSP PAYLOAD -------\n");
 	ql_dump_buffer(ql_dbg_init + ql_dbg_verbose, vha, 0x0187,
-	    (void *)rsp_payload, rsp_els->tx_byte_count);
+	    (void *)rsp_payload, rsp_payload_length);
 
 	rval = qla2x00_issue_iocb(vha, rsp_els, rsp_els_dma, 0);