scsi: pass down REQUEST SENSE to the device when there is no stored sense

This will let scsi-block/scsi-generic report progress on long
operations.
Reported-by: NThomas Schmitt <scdbackup@gmxbackup.net>
Tested-by: NThomas Schmitt <scdbackup@gmxbackup.net>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/scsi-bus.c

@@ -9,8 +9,6 @@
 static char *scsibus_get_fw_dev_path(DeviceState *dev);
 static int scsi_req_parse(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf);
 static void scsi_req_dequeue(SCSIRequest *req);
-static int scsi_build_sense(uint8_t *in_buf, int in_len,
-                            uint8_t *buf, int len, bool fixed);
 
 static struct BusInfo scsi_bus_info = {
     .name  = "SCSI",
@@ -502,7 +500,7 @@ SCSIRequest *scsi_req_new(SCSIDevice *d, uint32_t tag, uint32_t lun,
                                  hba_private);
         } else if (lun != d->lun ||
             buf[0] == REPORT_LUNS ||
-            buf[0] == REQUEST_SENSE) {
+            (buf[0] == REQUEST_SENSE && (d->sense_len || cmd.xfer < 4))) {
             req = scsi_req_alloc(&reqops_target_command, d, tag, lun,
                                  hba_private);
         } else {

hw/scsi-disk.c

@@ -1179,6 +1179,11 @@ static int scsi_disk_emulate_command(SCSIDiskReq *r)
         outbuf[7] = 0;
         buflen = 8;
         break;
+    case REQUEST_SENSE:
+        /* Just return "NO SENSE".  */
+        buflen = scsi_build_sense(NULL, 0, outbuf, r->buflen,
+                                  (req->cmd.buf[1] & 1) == 0);
+        break;
     case MECHANISM_STATUS:
         buflen = scsi_emulate_mechanism_status(s, outbuf);
         if (buflen < 0) {
@@ -1313,6 +1318,7 @@ static int32_t scsi_send_command(SCSIRequest *req, uint8_t *buf)
     case GET_EVENT_STATUS_NOTIFICATION:
     case MECHANISM_STATUS:
     case SERVICE_ACTION_IN_16:
+    case REQUEST_SENSE:
     case VERIFY_10:
         rc = scsi_disk_emulate_command(r);
         if (rc < 0) {
@@ -1407,8 +1413,6 @@ static int32_t scsi_send_command(SCSIRequest *req, uint8_t *buf)
         }
 
         break;
-    case REQUEST_SENSE:
-        abort();
     default:
         DPRINTF("Unknown SCSI command (%2.2x)\n", buf[0]);
         scsi_check_condition(r, SENSE_CODE(INVALID_OPCODE));

hw/scsi.h

@@ -179,6 +179,8 @@ extern const struct SCSISense sense_code_DEVICE_INTERNAL_RESET;
 #define SENSE_CODE(x) sense_code_ ## x
 
 int scsi_sense_valid(SCSISense sense);
+int scsi_build_sense(uint8_t *in_buf, int in_len,
+                     uint8_t *buf, int len, bool fixed);
 
 SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d,
                             uint32_t tag, uint32_t lun, void *hba_private);