pc-bios/s390-ccw: add boot entry selection to El Torito routine

If there is no LOADPARM given or '0' specified, then IPL the first
matched entry. Otherwise IPL the matching entry of that number.
Signed-off-by: NEugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Signed-off-by: NFarhan Ali <alifm@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

pc-bios/s390-ccw/bootmap.c

@@ -655,6 +655,7 @@ static IsoBcSection *find_iso_bc_entry(void)
     IsoBcEntry *e = (IsoBcEntry *)sec;
     uint32_t offset = find_iso_bc();
     int i;
+    unsigned int loadparm = get_loadparm_index();
 
     if (!offset) {
         return NULL;
@@ -675,7 +676,11 @@ static IsoBcSection *find_iso_bc_entry(void)
     for (i = 1; i < ISO_BC_ENTRY_PER_SECTOR; i++) {
         if (e[i].id == ISO_BC_BOOTABLE_SECTION) {
             if (is_iso_bc_entry_compatible(&e[i].body.sect)) {
-                return &e[i].body.sect;
+                if (loadparm <= 1) {
+                    /* found, default, or unspecified */
+                    return &e[i].body.sect;
+                }
+                loadparm--;
             }
         }
     }