block: Fix virtual media change for if=none

BlockDriverState member removable controls whether virtual media
change (monitor commands change, eject) is allowed.  It is set when
the "type hint" is BDRV_TYPE_CDROM or BDRV_TYPE_FLOPPY.

The type hint is only set by drive_init().  It sets BDRV_TYPE_FLOPPY
for if=floppy.  It sets BDRV_TYPE_CDROM for media=cdrom and if=ide,
scsi, xen, or none.

if=ide and if=scsi work, because the type hint makes it a CD-ROM.
if=xen likewise, I think.

For the same reason, if=none works when it's used by ide-drive or
scsi-disk.  For other guest devices, there are problems:

* fdc: you can't change virtual media

    $ qemu [...] -drive if=none,id=foo,... -global isa-fdc.driveA=foo
    QEMU 0.12.50 monitor - type 'help' for more information
    (qemu) eject foo
    Device 'foo' is not removable

  unless you add media=cdrom, but that makes it readonly.

* virtio: if you add media=cdrom, you can change virtual media.  If
  you eject, the guest gets I/O errors.  If you change, the guest sees
  the drive's contents suddenly change.

* scsi-generic: if you add media=cdrom, you can change virtual media.
  I didn't test what that does to the guest or the physical device,
  but it can't be pretty.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index e900eff024..3e41011ccb 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -1049,6 +1049,7 @@ static void scsi_destroy(SCSIDevice *dev)
 static int scsi_disk_initfn(SCSIDevice *dev)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
+    int is_cd;
     DriveInfo *dinfo;
 
     if (!s->qdev.conf.bs) {
@@ -1056,6 +1057,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
         return -1;
     }
     s->bs = s->qdev.conf.bs;
+    is_cd = bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM;
 
     if (!s->serial) {
         /* try to fall back to value set with legacy -drive serial=... */
@@ -1072,7 +1074,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
         return -1;
     }
 
-    if (bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM) {
+    if (is_cd) {
         s->qdev.blocksize = 2048;
     } else {
         s->qdev.blocksize = s->qdev.conf.logical_block_size;
@@ -1081,6 +1083,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
 
     s->qdev.type = TYPE_DISK;
     qemu_add_vm_change_state_handler(scsi_dma_restart_cb, s);
+    bdrv_set_removable(s->bs, is_cd);
     return 0;
 }