scsi-disk: Mask out serial number EVPD

If the serial number is not set we should mask it out in the
list of supported VPD pages and mark it as not supported.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/scsi-disk.c

@@ -398,7 +398,8 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
                     "buffer size %zd\n", req->cmd.xfer);
             pages = buflen++;
             outbuf[buflen++] = 0x00; // list of supported pages (this page)
-            outbuf[buflen++] = 0x80; // unit serial number
+            if (s->serial)
+                outbuf[buflen++] = 0x80; // unit serial number
             outbuf[buflen++] = 0x83; // device identification
             if (s->drive_kind == SCSI_HD) {
                 outbuf[buflen++] = 0xb0; // block limits
@@ -409,8 +410,14 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
         }
         case 0x80: /* Device serial number, optional */
         {
-            int l = strlen(s->serial);
+            int l;
 
+            if (!s->serial) {
+                DPRINTF("Inquiry (EVPD[Serial number] not supported\n");
+                return -1;
+            }
+
+            l = strlen(s->serial);
             if (l > req->cmd.xfer)
                 l = req->cmd.xfer;
             if (l > 20)
@@ -1203,7 +1210,9 @@ static int scsi_initfn(SCSIDevice *dev, SCSIDriveKind kind)
     if (!s->serial) {
         /* try to fall back to value set with legacy -drive serial=... */
         dinfo = drive_get_by_blockdev(s->bs);
-        s->serial = qemu_strdup(*dinfo->serial ? dinfo->serial : "0");
+        if (*dinfo->serial) {
+            s->serial = qemu_strdup(dinfo->serial);
+        }
     }
 
     if (!s->version) {