scsi-bus: prepare scsi_req_new for introduction of parse_cdb

The per-SCSIDevice parse_cdb callback must not be called if the
request will go through special SCSIReqOps, so detect the special
cases early enough.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-bus.c

@@ -561,13 +561,38 @@ SCSIRequest *scsi_req_new(SCSIDevice *d, uint32_t tag, uint32_t lun,
                           uint8_t *buf, void *hba_private)
 {
     SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, d->qdev.parent_bus);
+    const SCSIReqOps *ops;
     SCSIRequest *req;
-    SCSICommand cmd;
+    SCSICommand cmd = { .len = 0 };
+    int ret;
+
+    if ((d->unit_attention.key == UNIT_ATTENTION ||
+         bus->unit_attention.key == UNIT_ATTENTION) &&
+        (buf[0] != INQUIRY &&
+         buf[0] != REPORT_LUNS &&
+         buf[0] != GET_CONFIGURATION &&
+         buf[0] != GET_EVENT_STATUS_NOTIFICATION &&
+
+         /*
+          * If we already have a pending unit attention condition,
+          * report this one before triggering another one.
+          */
+         !(buf[0] == REQUEST_SENSE && d->sense_is_ua))) {
+        ops = &reqops_unit_attention;
+    } else if (lun != d->lun ||
+               buf[0] == REPORT_LUNS ||
+               (buf[0] == REQUEST_SENSE && d->sense_len)) {
+        ops = &reqops_target_command;
+    } else {
+        ops = NULL;
+    }
 
-    if (scsi_req_parse(&cmd, d, buf) != 0) {
+    ret = scsi_req_parse(&cmd, d, buf);
+    if (ret != 0) {
         trace_scsi_req_parse_bad(d->id, lun, tag, buf[0]);
         req = scsi_req_alloc(&reqops_invalid_opcode, d, tag, lun, hba_private);
     } else {
+        assert(cmd.len != 0);
         trace_scsi_req_parsed(d->id, lun, tag, buf[0],
                               cmd.mode, cmd.xfer);
         if (cmd.lba != -1) {
@@ -577,25 +602,8 @@ SCSIRequest *scsi_req_new(SCSIDevice *d, uint32_t tag, uint32_t lun,
 
         if (cmd.xfer > INT32_MAX) {
             req = scsi_req_alloc(&reqops_invalid_field, d, tag, lun, hba_private);
-        } else if ((d->unit_attention.key == UNIT_ATTENTION ||
-                   bus->unit_attention.key == UNIT_ATTENTION) &&
-                  (buf[0] != INQUIRY &&
-                   buf[0] != REPORT_LUNS &&
-                   buf[0] != GET_CONFIGURATION &&
-                   buf[0] != GET_EVENT_STATUS_NOTIFICATION &&
-
-                   /*
-                    * If we already have a pending unit attention condition,
-                    * report this one before triggering another one.
-                    */
-                   !(buf[0] == REQUEST_SENSE && d->sense_is_ua))) {
-            req = scsi_req_alloc(&reqops_unit_attention, d, tag, lun,
-                                 hba_private);
-        } else if (lun != d->lun ||
-                   buf[0] == REPORT_LUNS ||
-                   (buf[0] == REQUEST_SENSE && d->sense_len)) {
-            req = scsi_req_alloc(&reqops_target_command, d, tag, lun,
-                                 hba_private);
+        } else if (ops) {
+            req = scsi_req_alloc(ops, d, tag, lun, hba_private);
         } else {
             req = scsi_device_alloc_req(d, tag, lun, buf, hba_private);
         }
@@ -1186,6 +1194,7 @@ static int scsi_req_parse(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
 {
     int rc;
 
+    cmd->lba = -1;
     switch (buf[0] >> 5) {
     case 0:
         cmd->len = 6;