firmware: arm_scmi: Fix NULL pointer dereference during fastchannel init

The scmi_perf_domain_lookup requires the protocol handle to have the
private data set, which is yet to happen during the fastchannel init
scenario. This results in a NULL pointer dereference. Fix this by using
the pre-populated perf_dom_info to pass on the required information
instead.

  |  scmi_perf_protocol_init+0x434/0x678
  |  scmi_get_protocol_instance+0x168/0x29c
  |  scmi_devres_protocol_instance_get+0x50/0xa0
  |  scmi_devm_protocol_get+0x20/0x50
  |  scmi_cpufreq_probe+0x34/0xd4
  |  scmi_dev_probe+0x28/0x3c
  |  really_probe+0x148/0x2ac
  |  __driver_probe_device+0x78/0x12c
  |  driver_probe_device+0x40/0x160
  |  __device_attach_driver+0xb8/0x134
  |  bus_for_each_drv+0x80/0xdc
  |  __device_attach+0xa8/0x1b0
  |  device_initial_probe+0x14/0x20
  |  bus_probe_device+0xa8/0xac
  |  device_add+0x5cc/0x778
  |  device_register+0x20/0x30
  |  __scmi_device_create.part.0+0xec/0x1cc
  |  scmi_device_create+0x180/0x1c4
  |  scmi_create_protocol_devices+0x4c/0xb0
  |  scmi_probe+0x660/0x738
  |  platform_probe+0x68/0xdc
  |  really_probe+0x148/0x2ac
  |  __driver_probe_device+0x78/0x12c
  |  driver_probe_device+0x40/0x160
  |  __device_attach_driver+0xb8/0x134
  |  bus_for_each_drv+0x80/0xdc
  |  __device_attach+0xa8/0x1b0
  |  device_initial_probe+0x14/0x20
  |  bus_probe_device+0xa8/0xac
  |  deferred_probe_work_func+0x88/0xc0
  |  process_one_work+0x13c/0x264
  |  worker_thread+0x32c/0x438
  |  kthread+0x118/0x11c
  |  ret_from_fork+0x10/0x20

Fixes: 619bc6e0 ("firmware: arm_scmi: Populate fastchannel info only if set operations are allowed")
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
Link: https://lore.kernel.org/r/20231129065748.19871-2-quic_sibis@quicinc.comReviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/perf.c

@@ -759,40 +759,35 @@ static int scmi_perf_level_limits_notify(const struct scmi_protocol_handle *ph,
 }
 
 static void scmi_perf_domain_init_fc(const struct scmi_protocol_handle *ph,
-				     u32 domain, struct scmi_fc_info **p_fc)
+				     struct perf_dom_info *dom)
 {
 	struct scmi_fc_info *fc;
-	struct perf_dom_info *dom;
-
-	dom = scmi_perf_domain_lookup(ph, domain);
-	if (IS_ERR(dom))
-		return;
 
 	fc = devm_kcalloc(ph->dev, PERF_FC_MAX, sizeof(*fc), GFP_KERNEL);
 	if (!fc)
 		return;
 
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LEVEL_GET, 4, domain,
+				   PERF_LEVEL_GET, 4, dom->id,
 				   &fc[PERF_FC_LEVEL].get_addr, NULL);
 
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LIMITS_GET, 8, domain,
+				   PERF_LIMITS_GET, 8, dom->id,
 				   &fc[PERF_FC_LIMIT].get_addr, NULL);
 
 	if (dom->info.set_perf)
 		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-					   PERF_LEVEL_SET, 4, domain,
+					   PERF_LEVEL_SET, 4, dom->id,
 					   &fc[PERF_FC_LEVEL].set_addr,
 					   &fc[PERF_FC_LEVEL].set_db);
 
 	if (dom->set_limits)
 		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-					   PERF_LIMITS_SET, 8, domain,
+					   PERF_LIMITS_SET, 8, dom->id,
 					   &fc[PERF_FC_LIMIT].set_addr,
 					   &fc[PERF_FC_LIMIT].set_db);
 
-	*p_fc = fc;
+	dom->fc_info = fc;
 }
 
 static int scmi_dvfs_device_opps_add(const struct scmi_protocol_handle *ph,
@@ -1102,7 +1097,7 @@ static int scmi_perf_protocol_init(const struct scmi_protocol_handle *ph)
 		scmi_perf_describe_levels_get(ph, dom, version);
 
 		if (dom->perf_fastchannels)
-			scmi_perf_domain_init_fc(ph, dom->id, &dom->fc_info);
+			scmi_perf_domain_init_fc(ph, dom);
 	}
 
 	ret = devm_add_action_or_reset(ph->dev, scmi_perf_xa_destroy, pinfo);