scsi: lpfc: size cpu map by last cpu id set

Currently the lpfc driver sizes its cpu_map array based on
num_possible_cpus(). However, that can be a value that is less than the
highest cpu id bit that is set. As such, if a thread runs on a cpu with a
larger cpu id, or for_each_possible_cpu() is used, the driver could index
off the end of the array and return garbage or GPF.

The driver maintains its own internal copy of the "num_possible" cpu value
and sizes arrays by it.

Fix by setting the driver's value to the value of the last cpu id bit set
in the possible_mask - plus 1. Thus cpu_map will be sized to allow access
by any cpu id possible.

Link: https://lore.kernel.org/r/20191121175556.18953-1-jsmart2021@gmail.com
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_init.c

@@ -6460,7 +6460,7 @@ lpfc_sli4_driver_resource_setup(struct lpfc_hba *phba)
 	u32 if_fam;
 
 	phba->sli4_hba.num_present_cpu = lpfc_present_cpu;
-	phba->sli4_hba.num_possible_cpu = num_possible_cpus();
+	phba->sli4_hba.num_possible_cpu = cpumask_last(cpu_possible_mask) + 1;
 	phba->sli4_hba.curr_disp_cpu = 0;
 	lpfc_cpumask_of_node_init(phba);