diff --git a/blockdev.c b/blockdev.c
index dbf0251..aba7aaf 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -15,6 +15,7 @@
 #include "qemu-config.h"
 #include "sysemu.h"
 #include "block_int.h"
+#include "qmp-commands.h"
 
 static QTAILQ_HEAD(drivelist, DriveInfo) drives = QTAILQ_HEAD_INITIALIZER(drives);
 
@@ -710,28 +711,25 @@ int do_eject(Monitor *mon, const QDict *qdict, QObject **ret_data)
     return eject_device(mon, bs, force);
 }
 
-int do_block_set_passwd(Monitor *mon, const QDict *qdict,
-                        QObject **ret_data)
+void qmp_block_passwd(const char *device, const char *password, Error **errp)
 {
     BlockDriverState *bs;
     int err;
 
-    bs = bdrv_find(qdict_get_str(qdict, "device"));
+    bs = bdrv_find(device);
     if (!bs) {
-        qerror_report(QERR_DEVICE_NOT_FOUND, qdict_get_str(qdict, "device"));
-        return -1;
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
     }
 
-    err = bdrv_set_key(bs, qdict_get_str(qdict, "password"));
+    err = bdrv_set_key(bs, password);
     if (err == -EINVAL) {
-        qerror_report(QERR_DEVICE_NOT_ENCRYPTED, bdrv_get_device_name(bs));
-        return -1;
+        error_set(errp, QERR_DEVICE_NOT_ENCRYPTED, bdrv_get_device_name(bs));
+        return;
     } else if (err < 0) {
-        qerror_report(QERR_INVALID_PASSWORD);
-        return -1;
+        error_set(errp, QERR_INVALID_PASSWORD);
+        return;
     }
-
-    return 0;
 }
 
 int do_change_block(Monitor *mon, const char *device,
diff --git a/blockdev.h b/blockdev.h
index 1b48a75..93311a9 100644
--- a/blockdev.h
+++ b/blockdev.h
@@ -59,7 +59,6 @@ DriveInfo *add_init_drive(const char *opts);
 
 void do_commit(Monitor *mon, const QDict *qdict);
 int do_eject(Monitor *mon, const QDict *qdict, QObject **ret_data);
-int do_block_set_passwd(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_change_block(Monitor *mon, const char *device,
                     const char *filename, const char *fmt);
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 93d4a7e..0bf8896 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1198,8 +1198,7 @@ ETEXI
         .args_type  = "device:B,password:s",
         .params     = "block_passwd device password",
         .help       = "set the password of encrypted block devices",
-        .user_print = monitor_user_noop,
-        .mhandler.cmd_new = do_block_set_passwd,
+        .mhandler.cmd = hmp_block_passwd,
     },
 
 STEXI
diff --git a/hmp.c b/hmp.c
index 5d1687d..3893d59 100644
--- a/hmp.c
+++ b/hmp.c
@@ -611,3 +611,13 @@ void hmp_set_link(Monitor *mon, const QDict *qdict)
     qmp_set_link(name, up, &errp);
     hmp_handle_error(mon, &errp);
 }
+
+void hmp_block_passwd(Monitor *mon, const QDict *qdict)
+{
+    const char *device = qdict_get_str(qdict, "device");
+    const char *password = qdict_get_str(qdict, "password");
+    Error *errp = NULL;
+
+    qmp_block_passwd(device, password, &errp);
+    hmp_handle_error(mon, &errp);
+}
diff --git a/hmp.h b/hmp.h
index 32d7f68..d6aa232 100644
--- a/hmp.h
+++ b/hmp.h
@@ -42,5 +42,6 @@ void hmp_pmemsave(Monitor *mon, const QDict *qdict);
 void hmp_cont(Monitor *mon, const QDict *qdict);
 void hmp_inject_nmi(Monitor *mon, const QDict *qdict);
 void hmp_set_link(Monitor *mon, const QDict *qdict);
+void hmp_block_passwd(Monitor *mon, const QDict *qdict);
 
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 1d6fb4d..569aa74 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -999,3 +999,36 @@
 #        notification.
 ##
 { 'command': 'set_link', 'data': {'name': 'str', 'up': 'bool'} }
+
+##
+# @block_passwd:
+#
+# This command sets the password of a block device that has not been open
+# with a password and requires one.
+#
+# The two cases where this can happen are a block device is created through
+# QEMU's initial command line or a block device is changed through the legacy
+# @change interface.
+#
+# In the event that the block device is created through the initial command
+# line, the VM will start in the stopped state regardless of whether '-S' is
+# used.  The intention is for a management tool to query the block devices to
+# determine which ones are encrypted, set the passwords with this command, and
+# then start the guest with the @cont command.
+#
+# @device:   the name of the device to set the password on
+#
+# @password: the password to use for the device
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#          If @device is not encrypted, DeviceNotEncrypted
+#          If @password is not valid for this device, InvalidPassword
+#
+# Notes:  Not all block formats support encryption and some that do are not
+#         able to validate that a password is correct.  Disk corruption may
+#         occur if an invalid password is specified.
+#
+# Since: 0.14.0
+##
+{ 'command': 'block_passwd', 'data': {'device': 'str', 'password': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 5054da3..bbf9bfc 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -806,10 +806,7 @@ EQMP
     {
         .name       = "block_passwd",
         .args_type  = "device:B,password:s",
-        .params     = "block_passwd device password",
-        .help       = "set the password of encrypted block devices",
-        .user_print = monitor_user_noop,
-        .mhandler.cmd_new = do_block_set_passwd,
+        .mhandler.cmd_new = qmp_marshal_input_block_passwd,
     },
 
 SQMP
