--- /dev/null
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Stefan Reiter <s.reiter@proxmox.com>
+Date: Wed, 10 Feb 2021 11:07:06 +0100
+Subject: [PATCH] PBS: add master key support
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+this requires a new enough libproxmox-backup-qemu0, and allows querying
+from the PVE side to avoid QMP calls with unsupported parameters.
+
+Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
+Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
+Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+---
+ block/monitor/block-hmp-cmds.c | 1 +
+ pve-backup.c | 3 +++
+ qapi/block-core.json | 7 +++++++
+ 3 files changed, 11 insertions(+)
+
+diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
+index ef45552e3b..4c799f00d9 100644
+--- a/block/monitor/block-hmp-cmds.c
++++ b/block/monitor/block-hmp-cmds.c
+@@ -1039,6 +1039,7 @@ void coroutine_fn hmp_backup(Monitor *mon, const QDict *qdict)
+ false, NULL, // PBS password
+ false, NULL, // PBS keyfile
+ false, NULL, // PBS key_password
++ false, NULL, // PBS master_keyfile
+ false, NULL, // PBS fingerprint
+ false, NULL, // PBS backup-id
+ false, 0, // PBS backup-time
+diff --git a/pve-backup.c b/pve-backup.c
+index 323014744c..9f6c04a512 100644
+--- a/pve-backup.c
++++ b/pve-backup.c
+@@ -533,6 +533,7 @@ UuidInfo coroutine_fn *qmp_backup(
+ bool has_password, const char *password,
+ bool has_keyfile, const char *keyfile,
+ bool has_key_password, const char *key_password,
++ bool has_master_keyfile, const char *master_keyfile,
+ bool has_fingerprint, const char *fingerprint,
+ bool has_backup_id, const char *backup_id,
+ bool has_backup_time, int64_t backup_time,
+@@ -681,6 +682,7 @@ UuidInfo coroutine_fn *qmp_backup(
+ has_password ? password : NULL,
+ has_keyfile ? keyfile : NULL,
+ has_key_password ? key_password : NULL,
++ has_master_keyfile ? master_keyfile : NULL,
+ has_compress ? compress : true,
+ has_encrypt ? encrypt : has_keyfile,
+ has_fingerprint ? fingerprint : NULL,
+@@ -1044,5 +1046,6 @@ ProxmoxSupportStatus *qmp_query_proxmox_support(Error **errp)
+ ret->pbs_dirty_bitmap_savevm = true;
+ ret->pbs_dirty_bitmap_migration = true;
+ ret->query_bitmap_info = true;
++ ret->pbs_masterkey = true;
+ return ret;
+ }
+diff --git a/qapi/block-core.json b/qapi/block-core.json
+index ca1966f54b..fc8a125451 100644
+--- a/qapi/block-core.json
++++ b/qapi/block-core.json
+@@ -813,6 +813,8 @@
+ #
+ # @key-password: password for keyfile (optional for format 'pbs')
+ #
++# @master-keyfile: PEM-formatted master public keyfile (optional for format 'pbs')
++#
+ # @fingerprint: server cert fingerprint (optional for format 'pbs')
+ #
+ # @backup-id: backup ID (required for format 'pbs')
+@@ -832,6 +834,7 @@
+ '*password': 'str',
+ '*keyfile': 'str',
+ '*key-password': 'str',
++ '*master-keyfile': 'str',
+ '*fingerprint': 'str',
+ '*backup-id': 'str',
+ '*backup-time': 'int',
+@@ -884,6 +887,9 @@
+ # migration cap if this is false/unset may lead
+ # to crashes on migration!
+ #
++# @pbs-masterkey: True if the QMP backup call supports the 'master_keyfile'
++# parameter.
++#
+ # @pbs-library-version: Running version of libproxmox-backup-qemu0 library.
+ #
+ ##
+@@ -892,6 +898,7 @@
+ 'query-bitmap-info': 'bool',
+ 'pbs-dirty-bitmap-savevm': 'bool',
+ 'pbs-dirty-bitmap-migration': 'bool',
++ 'pbs-masterkey': 'bool',
+ 'pbs-library-version': 'str' } }
+
+ ##