blockdev: Deprecate -drive with bogus interface type

Drives with interface types other than if=none are for onboard
devices.  Unfortunately, any such drives the board doesn't pick up can
still be used with -device, like this:

    $ qemu-system-x86_64 -nodefaults -display none -S -drive if=floppy,id=bogus,unit=7 -device ide-cd,drive=bogus -monitor stdio
    QEMU 5.0.50 monitor - type 'help' for more information
    (qemu) info block
    bogus: [not inserted]
	Attached to:      /machine/peripheral-anon/device[0]
	Removable device: not locked, tray closed
    (qemu) info qtree
    bus: main-system-bus
      type System
      [...]
	    bus: ide.1
	      type IDE
	      dev: ide-cd, id ""
--->		drive = "bogus"
		[...]
		unit = 0 (0x0)
      [...]

This kind of abuse has always worked.  Deprecate it:

    qemu-system-x86_64: -drive if=floppy,id=bogus,unit=7: warning: bogus if=floppy is deprecated, use if=none

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200622094227.1271650-9-armbru@redhat.com>

blockdev.c

@@ -239,6 +239,19 @@ DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit)
     return NULL;
 }
 
+void drive_mark_claimed_by_board(void)
+{
+    BlockBackend *blk;
+    DriveInfo *dinfo;
+
+    for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
+        dinfo = blk_legacy_dinfo(blk);
+        if (dinfo && blk_get_attached_dev(blk)) {
+            dinfo->claimed_by_board = true;
+        }
+    }
+}
+
 void drive_check_orphaned(void)
 {
     BlockBackend *blk;
@@ -248,8 +261,10 @@ void drive_check_orphaned(void)
 
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
         dinfo = blk_legacy_dinfo(blk);
-        if (!blk_get_attached_dev(blk) && !dinfo->is_default &&
-            dinfo->type != IF_NONE) {
+        if (dinfo->is_default || dinfo->type == IF_NONE) {
+            continue;
+        }
+        if (!blk_get_attached_dev(blk)) {
             loc_push_none(&loc);
             qemu_opts_loc_restore(dinfo->opts);
             error_report("machine type does not support"
@@ -257,6 +272,14 @@ void drive_check_orphaned(void)
                          if_name[dinfo->type], dinfo->bus, dinfo->unit);
             loc_pop(&loc);
             orphans = true;
+            continue;
+        }
+        if (!dinfo->claimed_by_board && dinfo->type != IF_VIRTIO) {
+            loc_push_none(&loc);
+            qemu_opts_loc_restore(dinfo->opts);
+            warn_report("bogus if=%s is deprecated, use if=none",
+                        if_name[dinfo->type]);
+            loc_pop(&loc);
         }
     }
 

docs/system/deprecated.rst

@@ -190,6 +190,14 @@ become
 
     -device floppy,unit=1,drive=...
 
+``-drive`` with bogus interface type
+''''''''''''''''''''''''''''''''''''
+
+Drives with interface types other than ``if=none`` are for onboard
+devices.  It is possible to use drives the board doesn't pick up with
+-device.  This usage is now deprecated.  Use ``if=none`` instead.
+
+
 QEMU Machine Protocol (QMP) commands
 ------------------------------------
 

include/sysemu/blockdev.h

@@ -35,6 +35,7 @@ struct DriveInfo {
     bool is_default;            /* Added by default_drive() ?  */
     int media_cd;
     QemuOpts *opts;
+    bool claimed_by_board;
     QTAILQ_ENTRY(DriveInfo) next;
 };
 
@@ -45,6 +46,7 @@ BlockBackend *blk_by_legacy_dinfo(DriveInfo *dinfo);
 void override_max_devs(BlockInterfaceType type, int max_devs);
 
 DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
+void drive_mark_claimed_by_board(void);
 void drive_check_orphaned(void);
 DriveInfo *drive_get_by_index(BlockInterfaceType type, int index);
 int drive_get_max_bus(BlockInterfaceType type);

softmmu/vl.c

@@ -4347,6 +4347,14 @@ void qemu_init(int argc, char **argv, char **envp)
     /* from here on runstate is RUN_STATE_PRELAUNCH */
     machine_run_board_init(current_machine);
 
+    /*
+     * TODO To drop support for deprecated bogus if=..., move
+     * drive_check_orphaned() here, replacing this call.  Also drop
+     * its deprecation warning, along with DriveInfo member
+     * @claimed_by_board.
+     */
+    drive_mark_claimed_by_board();
+
     realtime_init();
 
     soundhw_init();