scsi: introduce scsi_build_sense

Move more knowledge of sense data format out of hw/scsi/scsi-bus.c
for reusability.
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-bus.c

@@ -818,13 +818,7 @@ void scsi_req_build_sense(SCSIRequest *req, SCSISense sense)
 {
     trace_scsi_req_build_sense(req->dev->id, req->lun, req->tag,
                                sense.key, sense.asc, sense.ascq);
-    memset(req->sense, 0, 18);
-    req->sense[0] = 0x70;
-    req->sense[2] = sense.key;
-    req->sense[7] = 10;
-    req->sense[12] = sense.asc;
-    req->sense[13] = sense.ascq;
-    req->sense_len = 18;
+    req->sense_len = scsi_build_sense(req->sense, sense);
 }
 
 static void scsi_req_enqueue_internal(SCSIRequest *req)

include/scsi/utils.h

@@ -30,6 +30,8 @@ typedef struct SCSISense {
     uint8_t ascq;
 } SCSISense;
 
+int scsi_build_sense(uint8_t *buf, SCSISense sense);
+
 /*
  * Predefined sense codes
  */

scsi/utils.c

@@ -96,6 +96,17 @@ int scsi_cdb_length(uint8_t *buf)
     return cdb_len;
 }
 
+int scsi_build_sense(uint8_t *buf, SCSISense sense)
+{
+    memset(buf, 0, 18);
+    buf[0] = 0x70;
+    buf[2] = sense.key;
+    buf[7] = 10;
+    buf[12] = sense.asc;
+    buf[13] = sense.ascq;
+    return 18;
+}
+
 /*
  * Predefined sense codes
  */