pc-bios: s390x: cio.c cleanup and compile fix

Let's initialize the structs at the beginning to ease reading and also
zeroing all other fields. This also makes the compiler stop
complaining about sense_id_ccw.flags being ored into when it's not
initialized.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200624075226.92728-2-frankja@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/cio.c

@@ -49,13 +49,13 @@ void enable_subchannel(SubChannelId schid)
 
 uint16_t cu_type(SubChannelId schid)
 {
-    Ccw1 sense_id_ccw;
     SenseId sense_data;
-
-    sense_id_ccw.cmd_code = CCW_CMD_SENSE_ID;
-    sense_id_ccw.cda = ptr2u32(&sense_data);
-    sense_id_ccw.count = sizeof(sense_data);
-    sense_id_ccw.flags |= CCW_FLAG_SLI;
+    Ccw1 sense_id_ccw = {
+        .cmd_code = CCW_CMD_SENSE_ID,
+        .flags = CCW_FLAG_SLI,
+        .count = sizeof(sense_data),
+        .cda = ptr2u32(&sense_data),
+    };
 
     if (do_cio(schid, CU_TYPE_UNKNOWN, ptr2u32(&sense_id_ccw), CCW_FMT1)) {
         panic("Failed to run SenseID CCw\n");
@@ -67,13 +67,13 @@ uint16_t cu_type(SubChannelId schid)
 int basic_sense(SubChannelId schid, uint16_t cutype, void *sense_data,
                  uint16_t data_size)
 {
-    Ccw1 senseCcw;
+    Ccw1 senseCcw = {
+        .cmd_code = CCW_CMD_BASIC_SENSE,
+        .count = data_size,
+        .cda = ptr2u32(sense_data),
+    };
     Irb irb;
 
-    senseCcw.cmd_code = CCW_CMD_BASIC_SENSE;
-    senseCcw.cda = ptr2u32(sense_data);
-    senseCcw.count = data_size;
-
     return __do_cio(schid, ptr2u32(&senseCcw), CCW_FMT1, &irb);
 }
 
@@ -314,7 +314,17 @@ static void print_irb_err(Irb *irb)
  */
 static int __do_cio(SubChannelId schid, uint32_t ccw_addr, int fmt, Irb *irb)
 {
-    CmdOrb orb = {};
+    /*
+     * QEMU's CIO implementation requires prefetch and 64-bit idaws. We
+     * allow all paths.
+     */
+    CmdOrb orb = {
+        .fmt = fmt,
+        .pfch = 1,
+        .c64 = 1,
+        .lpm = 0xFF,
+        .cpa = ccw_addr,
+    };
     int rc;
 
     IPL_assert(fmt == 0 || fmt == 1, "Invalid ccw format");
@@ -324,12 +334,6 @@ static int __do_cio(SubChannelId schid, uint32_t ccw_addr, int fmt, Irb *irb)
         IPL_assert(ccw_addr <= 0xFFFFFF - 8, "Invalid ccw address");
     }
 
-    orb.fmt = fmt;
-    orb.pfch = 1;  /* QEMU's cio implementation requires prefetch */
-    orb.c64 = 1;   /* QEMU's cio implementation requires 64-bit idaws */
-    orb.lpm = 0xFF; /* All paths allowed */
-    orb.cpa = ccw_addr;
-
     rc = ssch(schid, &orb);
     if (rc == 1 || rc == 2) {
         /* Subchannel status pending or busy. Eat status and ask for retry. */