Implement drive_del to decouple block removal from device removal
Currently device hotplug removal code is tied to device removal via
ACPI. All pci devices that are removable via device_del() require the
guest to respond to the request. In some cases the guest may not
respond leaving the device still accessible to the guest. The management
layer doesn't currently have a reliable way to revoke access to host
resource in the presence of an uncooperative guest.
This patch implements a new monitor command, drive_del, which
provides an explicit command to revoke access to a host block device.
drive_del first quiesces the block device (qemu_aio_flush;
bdrv_flush() and bdrv_close()). This prevents further IO from being
submitted against the host device. Finally, drive_del cleans up
pointers between the drive object (host resource) and the device
object (guest resource).
Signed-off-by: Ryan Harper <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
diff --git a/hmp-commands.hx b/hmp-commands.hx
index e5585ba..23024ba 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -68,6 +68,24 @@
ETEXI
{
+ .name = "drive_del",
+ .args_type = "id:s",
+ .params = "device",
+ .help = "remove host block device",
+ .user_print = monitor_user_noop,
+ .mhandler.cmd_new = do_drive_del,
+ },
+
+STEXI
+@item drive_del @var{device}
+@findex drive_del
+Remove host block device. The result is that guest generated IO is no longer
+submitted against the host device underlying the disk. Once a drive has
+been deleted, the QEMU Block layer returns -EIO which results in IO
+errors in the guest for applications that are reading/writing to the device.
+ETEXI
+
+ {
.name = "change",
.args_type = "device:B,target:F,arg:s?",
.params = "device filename [format]",
