scsi: Handle no media case for scsi_get_configuration

Currently, scsi_get_configuration always returns a current
profile (DVD or CD), even when there is actually no media present.
By comparison, ide/atapi uses a default profile of 0 (MMC_PROFILE_NONE)
for this case and checks for tray_open, so let's do the same for scsi.

This fixes a problem I'm seeing with Fedora 22 guests where systemd
cdrom_id fails to unmount after a QEMU-initiated eject against a
scsi cdrom device because it believes the media is still present
(but unreadable).
Signed-off-by: NMatthew Rosato <mjrosato@linux.vnet.ibm.com>
Message-Id: <1436986352-10695-1-git-send-email-mjrosato@linux.vnet.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-disk.c

@@ -765,6 +765,9 @@ static inline bool media_is_dvd(SCSIDiskState *s)
     if (!blk_is_inserted(s->qdev.conf.blk)) {
         return false;
     }
+    if (s->tray_open) {
+        return false;
+    }
     blk_get_geometry(s->qdev.conf.blk, &nb_sectors);
     return nb_sectors > CD_MAX_SECTORS;
 }
@@ -778,6 +781,9 @@ static inline bool media_is_cd(SCSIDiskState *s)
     if (!blk_is_inserted(s->qdev.conf.blk)) {
         return false;
     }
+    if (s->tray_open) {
+        return false;
+    }
     blk_get_geometry(s->qdev.conf.blk, &nb_sectors);
     return nb_sectors <= CD_MAX_SECTORS;
 }
@@ -975,7 +981,15 @@ static int scsi_get_configuration(SCSIDiskState *s, uint8_t *outbuf)
     if (s->qdev.type != TYPE_ROM) {
         return -1;
     }
-    current = media_is_dvd(s) ? MMC_PROFILE_DVD_ROM : MMC_PROFILE_CD_ROM;
+
+    if (media_is_dvd(s)) {
+        current = MMC_PROFILE_DVD_ROM;
+    } else if (media_is_cd(s)) {
+        current = MMC_PROFILE_CD_ROM;
+    } else {
+        current = MMC_PROFILE_NONE;
+    }
+
     memset(outbuf, 0, 40);
     stl_be_p(&outbuf[0], 36); /* Bytes after the data length field */
     stw_be_p(&outbuf[6], current);