[Qemu-devel] [PATCH v3 0/5] QMP wrappers for VM snapshot operations

[Qemu-devel] [PATCH v3 0/5] QMP wrappers for VM snapshot operations

[Denis V. Lunev]

EFI based VM with pflash storage for NVRAM could not be snapshoted as
libvirt configures storage as 'raw' and writable. OK, this is a libvirt
problem.

Another problem is that libvirt can not detect this failure at all
as it uses HMP for this operation. This create snapshot/delete snapshot
sequence passes silently.

The patchset adds QMP wrappers for the purpose.

Signed-off-by: "Denis V. Lunev" <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>

Changes from v2:
- patches 1/2 are resplit to move processing HMP specific handling
  of snapshot name generation to exclusive HMP code
- removed all '.' at the end of error_setg strings
- fixed too long lines with '-' in qmp-commands.hx
- error_setg_errno errno passing is fixed (-ret)
- fixed logical error in hmp_loadvm (vm_start on error)
- NOT switched to error_prepend code (it is not yet merged). Can we do this
  later? This will make my life easear merging code to our downstream.

Changes from v1:
- cosmetic fixes suggested by Markus. I pray I have added all of them
- patch 5 is rewritten completely. Original one was deadbeaf

Denis V. Lunev (5):
  qmp: process system-reset event in paused state
  qmp: create qmp_savevm command
  qmp: create qmp_delvm command
  migration: improve error reporting for load_vmstate
  qmp: create QMP implementation of loadvm command

 hmp.c                         | 14 +++++++--
 include/migration/migration.h |  2 --
 include/sysemu/sysemu.h       |  2 +-
 migration/savevm.c            | 56 ++++++++++++++++++++--------------
 monitor.c                     |  9 +++---
 qapi-schema.json              | 39 ++++++++++++++++++++++++
 qmp-commands.hx               | 71 +++++++++++++++++++++++++++++++++++++++++++
 qmp.c                         |  4 +++
 vl.c                          |  4 ++-
 9 files changed, 168 insertions(+), 33 deletions(-)

-- 
2.5.0

[Qemu-devel] [PATCH 1/5] qmp: process system-reset event in paused state

[Denis V. Lunev]

With pvpanic or HyperV panic devices could be moved into the paused state
with ' <on_crash>preserve</on_crash>'. In this state VM reacts only to
'virsh destroy' or 'continue'.

'virsh reset' command is usually used to force guest reset. The expectation
of the behavior of this command is that the guest will be force restarted.
This is not true at the moment.

Thus it is quite natural to process 'virh reset' aka qmp_system_reset
this way, i.e. allow to reset the guest. This behavior is similar to
one observed with 'reset' button on real hardware :)

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Markus Armbruster <armbru@redhat.com>
CC: Dmitry Andreev <dandreev@virtuozzo.com>
---
 qmp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/qmp.c b/qmp.c
index 0a1fa19..df17a33 100644
--- a/qmp.c
+++ b/qmp.c
@@ -112,6 +112,10 @@ void qmp_stop(Error **errp)
 void qmp_system_reset(Error **errp)
 {
     qemu_system_reset_request();
+
+    if (!runstate_is_running()) {
+        vm_start();
+    }
 }
 
 void qmp_system_powerdown(Error **erp)
-- 
2.5.0

[Qemu-devel] [PATCH 2/5] qmp: create qmp_savevm command

[Denis V. Lunev]

'name' attribute is made mandatory in distinction with HMP command.

The patch also moves hmp_savevm implementation into hmp.c. This function
is just a simple wrapper now and does not have knowledge about
migration internals.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 hmp.c                         |  3 +--
 include/migration/migration.h |  2 --
 migration/savevm.c            |  2 +-
 qapi-schema.json              | 13 +++++++++++++
 qmp-commands.hx               | 25 +++++++++++++++++++++++++
 5 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/hmp.c b/hmp.c
index e7bab75..8d6eda6 100644
--- a/hmp.c
+++ b/hmp.c
@@ -33,7 +33,6 @@
 #include "ui/console.h"
 #include "block/qapi.h"
 #include "qemu-io.h"
-#include "migration/migration.h"
 
 #ifdef CONFIG_SPICE
 #include <spice/enums.h>
@@ -2406,7 +2405,7 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
         name = name_buf;
     }
 
-    migrate_savevm(name, &local_err);
+    qmp_savevm(name, &local_err);
 
     if (local_err != NULL) {
         error_report_err(local_err);
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 73c8bb1..58c04a9 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -277,8 +277,6 @@ int migrate_compress_threads(void);
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
 
-void migrate_savevm(const char *name, Error **errp);
-
 /* Sending on the return path - generic and then for each message type */
 void migrate_send_rp_message(MigrationIncomingState *mis,
                              enum mig_rp_message_type message_type,
diff --git a/migration/savevm.c b/migration/savevm.c
index 308302a..0dbb15f 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1905,7 +1905,7 @@ int qemu_loadvm_state(QEMUFile *f)
     return ret;
 }
 
-void migrate_savevm(const char *name, Error **errp)
+void qmp_savevm(const char *name, Error **errp)
 {
     BlockDriverState *bs, *bs1;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
diff --git a/qapi-schema.json b/qapi-schema.json
index 2e31733..09d1a1a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4054,3 +4054,16 @@
 ##
 { 'enum': 'ReplayMode',
   'data': [ 'none', 'record', 'play' ] }
+
+##
+# @savevm
+#
+# Save a VM snapshot. Old snapshot with the same name will be deleted if exists.
+#
+# @name: identifier of a snapshot to be created
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'savevm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index db072a6..b7851e1 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4795,3 +4795,28 @@ Example:
                  {"type": 0, "out-pport": 0, "pport": 0, "vlan-id": 3840,
                   "pop-vlan": 1, "id": 251658240}
    ]}
+
+EQMP
+
+SQMP
+savevm
+------
+
+Save a VM snapshot. Old snapshot with the same name will be deleted if exists.
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "savevm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "savevm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_savevm,
+    },
-- 
2.5.0

[Qemu-devel] [PATCH 3/5] qmp: create qmp_delvm command

[Denis V. Lunev]

The patch also moves hmp_delvm implementation into hmp.c. This function
is just a simple wrapper now and does not have knowledge about
migration internals.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 hmp.c              | 11 +++++++++++
 migration/savevm.c | 16 +++++++---------
 qapi-schema.json   | 13 +++++++++++++
 qmp-commands.hx    | 23 +++++++++++++++++++++++
 4 files changed, 54 insertions(+), 9 deletions(-)

diff --git a/hmp.c b/hmp.c
index 8d6eda6..f65bbe7 100644
--- a/hmp.c
+++ b/hmp.c
@@ -2411,3 +2411,14 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
         error_report_err(local_err);
     }
 }
+
+void hmp_delvm(Monitor *mon, const QDict *qdict)
+{
+    Error *local_err = NULL;
+
+    qmp_delvm(qdict_get_str(qdict, "name"), &local_err);
+
+    if (local_err != NULL) {
+        error_report_err(local_err);
+    }
+}
diff --git a/migration/savevm.c b/migration/savevm.c
index 0dbb15f..1262b57 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2092,17 +2092,15 @@ int load_vmstate(const char *name)
     return 0;
 }
 
-void hmp_delvm(Monitor *mon, const QDict *qdict)
+void qmp_delvm(const char *name, Error **errp)
 {
     BlockDriverState *bs;
-    Error *err;
-    const char *name = qdict_get_str(qdict, "name");
-
-    if (bdrv_all_delete_snapshot(name, &bs, &err) < 0) {
-        monitor_printf(mon,
-                       "Error while deleting snapshot on device '%s': %s\n",
-                       bdrv_get_device_name(bs), error_get_pretty(err));
-        error_free(err);
+    Error *local_err = NULL;
+
+    if (bdrv_all_delete_snapshot(name, &bs, &local_err) < 0) {
+        error_setg(errp, "Error while deleting snapshot on device '%s': %s",
+                   bdrv_get_device_name(bs), error_get_pretty(local_err));
+        error_free(local_err);
     }
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index 09d1a1a..94a2764 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4067,3 +4067,16 @@
 # Since 2.6
 ##
 { 'command': 'savevm', 'data': {'name': 'str'} }
+
+##
+# @delvm
+#
+# Delete a VM snapshot
+#
+# @name: identifier of a snapshot to be deleted
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'delvm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index b7851e1..5e6f573 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4820,3 +4820,26 @@ EQMP
         .args_type  = "name:s",
         .mhandler.cmd_new = qmp_marshal_savevm,
     },
+
+SQMP
+delvm
+-----
+
+Delete a VM snapshot
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "delvm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "delvm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_delvm,
+    },
-- 
2.5.0

[Qemu-devel] [PATCH 4/5] migration: improve error reporting for load_vmstate

[Denis V. Lunev]

The patch adds Error ** parameter to load_vmstate call and fills error
inside. The caller after that properly reports error either through
monitor or via local stderr facility during VM start.

This helper will be useful too for qmp_loadvm implementation.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 include/sysemu/sysemu.h |  2 +-
 migration/savevm.c      | 28 ++++++++++++++++------------
 monitor.c               |  5 ++++-
 vl.c                    |  4 +++-
 4 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 3bb8897..d9ccf45 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -78,7 +78,7 @@ void qemu_remove_exit_notifier(Notifier *notify);
 void qemu_add_machine_init_done_notifier(Notifier *notify);
 
 void hmp_savevm(Monitor *mon, const QDict *qdict);
-int load_vmstate(const char *name);
+int load_vmstate(const char *name, Error **errp);
 void hmp_delvm(Monitor *mon, const QDict *qdict);
 void hmp_info_snapshots(Monitor *mon, const QDict *qdict);
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 1262b57..3de917e 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2019,7 +2019,7 @@ void qmp_xen_save_devices_state(const char *filename, Error **errp)
     }
 }
 
-int load_vmstate(const char *name)
+int load_vmstate(const char *name, Error **errp)
 {
     BlockDriverState *bs, *bs_vm_state;
     QEMUSnapshotInfo sn;
@@ -2028,20 +2028,22 @@ int load_vmstate(const char *name)
     AioContext *aio_context;
 
     if (!bdrv_all_can_snapshot(&bs)) {
-        error_report("Device '%s' is writable but does not support snapshots.",
-                     bdrv_get_device_name(bs));
+        error_setg(errp,
+                   "Device '%s' is writable but does not support snapshots",
+                   bdrv_get_device_name(bs));
         return -ENOTSUP;
     }
     ret = bdrv_all_find_snapshot(name, &bs);
     if (ret < 0) {
-        error_report("Device '%s' does not have the requested snapshot '%s'",
-                     bdrv_get_device_name(bs), name);
+        error_setg(errp,
+                   "Device '%s' does not have the requested snapshot '%s'",
+                   bdrv_get_device_name(bs), name);
         return ret;
     }
 
     bs_vm_state = bdrv_all_find_vmstate_bs();
     if (!bs_vm_state) {
-        error_report("No block device supports snapshots");
+        error_setg(errp, "No block device supports snapshots");
         return -ENOTSUP;
     }
     aio_context = bdrv_get_aio_context(bs_vm_state);
@@ -2051,10 +2053,11 @@ int load_vmstate(const char *name)
     ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
     aio_context_release(aio_context);
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "Snapshot '%s' not found", name);
         return ret;
     } else if (sn.vm_state_size == 0) {
-        error_report("This is a disk-only snapshot. Revert to it offline "
-            "using qemu-img.");
+        error_setg(errp, "Snapshot '%s' is a disk-only snapshot and must be "
+                   "reverted offline using qemu-img", name);
         return -EINVAL;
     }
 
@@ -2063,15 +2066,16 @@ int load_vmstate(const char *name)
 
     ret = bdrv_all_goto_snapshot(name, &bs);
     if (ret < 0) {
-        error_report("Error %d while activating snapshot '%s' on '%s'",
-                     ret, name, bdrv_get_device_name(bs));
+        error_setg_errno(errp, -ret,
+                         "Error while activating snapshot '%s' on '%s'",
+                         name, bdrv_get_device_name(bs));
         return ret;
     }
 
     /* restore the VM state */
     f = qemu_fopen_bdrv(bs_vm_state, 0);
     if (!f) {
-        error_report("Could not open VM state file");
+        error_setg(errp, "Could not open VM state file");
         return -EINVAL;
     }
 
@@ -2085,7 +2089,7 @@ int load_vmstate(const char *name)
 
     migration_incoming_state_destroy();
     if (ret < 0) {
-        error_report("Error %d while loading VM state", ret);
+        error_setg_errno(errp, -ret, "Error while loading VM state");
         return ret;
     }
 
diff --git a/monitor.c b/monitor.c
index e7e7ae2..2ddf6c1 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1739,10 +1739,13 @@ static void hmp_loadvm(Monitor *mon, const QDict *qdict)
 {
     int saved_vm_running  = runstate_is_running();
     const char *name = qdict_get_str(qdict, "name");
+    Error *local_err = NULL;
 
     vm_stop(RUN_STATE_RESTORE_VM);
 
-    if (load_vmstate(name) == 0 && saved_vm_running) {
+    if (load_vmstate(name, &local_err) < 0) {
+        error_report_err(local_err);
+    } else if (saved_vm_running) {
         vm_start();
     }
 }
diff --git a/vl.c b/vl.c
index 5aaea77..0172e42 100644
--- a/vl.c
+++ b/vl.c
@@ -4648,8 +4648,10 @@ int main(int argc, char **argv, char **envp)
     qemu_system_reset(VMRESET_SILENT);
     register_global_state();
     if (loadvm) {
-        if (load_vmstate(loadvm) < 0) {
+        Error *local_err = NULL;
+        if (load_vmstate(loadvm, &local_err) < 0) {
             autostart = 0;
+            error_report_err(local_err);
         }
     }
 
-- 
2.5.0

[Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Denis V. Lunev]

Unfortunately load_vmstate has a return code (int) and this code is checked
in the other places. Thus we could not just rename it to qmp_loadvm as
returns void.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 migration/savevm.c | 10 ++++++++++
 monitor.c          |  8 ++------
 qapi-schema.json   | 13 +++++++++++++
 qmp-commands.hx    | 23 +++++++++++++++++++++++
 4 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index 3de917e..6b34017 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2096,6 +2096,16 @@ int load_vmstate(const char *name, Error **errp)
     return 0;
 }
 
+void qmp_loadvm(const char *name, Error **errp)
+{
+    int saved_vm_running  = runstate_is_running();
+    vm_stop(RUN_STATE_RESTORE_VM);
+
+    if (load_vmstate(name, errp) == 0 && saved_vm_running) {
+        vm_start();
+    }
+}
+
 void qmp_delvm(const char *name, Error **errp)
 {
     BlockDriverState *bs;
diff --git a/monitor.c b/monitor.c
index 2ddf6c1..c1e998c 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1737,16 +1737,12 @@ void qmp_closefd(const char *fdname, Error **errp)
 
 static void hmp_loadvm(Monitor *mon, const QDict *qdict)
 {
-    int saved_vm_running  = runstate_is_running();
     const char *name = qdict_get_str(qdict, "name");
     Error *local_err = NULL;
 
-    vm_stop(RUN_STATE_RESTORE_VM);
-
-    if (load_vmstate(name, &local_err) < 0) {
+    qmp_loadvm(name, &local_err);
+    if (local_err != NULL) {
         error_report_err(local_err);
-    } else if (saved_vm_running) {
-        vm_start();
     }
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index 94a2764..7d48948 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4080,3 +4080,16 @@
 # Since 2.6
 ##
 { 'command': 'delvm', 'data': {'name': 'str'} }
+
+##
+# @loadvm
+#
+# Load a VM snapshot
+#
+# @name: identifier of a snapshot to be loaded
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'loadvm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 5e6f573..9cd1bfe 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4843,3 +4843,26 @@ EQMP
         .args_type  = "name:s",
         .mhandler.cmd_new = qmp_marshal_delvm,
     },
+
+SQMP
+loadvm
+------
+
+Load a VM snapshot
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "loadvm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "loadvm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_loadvm,
+    },
-- 
2.5.0

Re: [Qemu-devel] [PATCH v3 0/5] QMP wrappers for VM snapshot operations

[Denis V. Lunev]

On 01/08/2016 05:00 PM, Denis V. Lunev wrote:
> EFI based VM with pflash storage for NVRAM could not be snapshoted as
> libvirt configures storage as 'raw' and writable. OK, this is a libvirt
> problem.
>
> Another problem is that libvirt can not detect this failure at all
> as it uses HMP for this operation. This create snapshot/delete snapshot
> sequence passes silently.
>
> The patchset adds QMP wrappers for the purpose.
>
> Signed-off-by: "Denis V. Lunev" <den@openvz.org>
> CC: Juan Quintela <quintela@redhat.com>
> CC: Amit Shah <amit.shah@redhat.com>
> CC: Markus Armbruster <armbru@redhat.com>
> CC: Eric Blake <eblake@redhat.com>
>
> Changes from v2:
> - patches 1/2 are resplit to move processing HMP specific handling
>    of snapshot name generation to exclusive HMP code
> - removed all '.' at the end of error_setg strings
> - fixed too long lines with '-' in qmp-commands.hx
> - error_setg_errno errno passing is fixed (-ret)
> - fixed logical error in hmp_loadvm (vm_start on error)
> - NOT switched to error_prepend code (it is not yet merged). Can we do this
>    later? This will make my life easear merging code to our downstream.
>
> Changes from v1:
> - cosmetic fixes suggested by Markus. I pray I have added all of them
> - patch 5 is rewritten completely. Original one was deadbeaf
>
> Denis V. Lunev (5):
>    qmp: process system-reset event in paused state
>    qmp: create qmp_savevm command
>    qmp: create qmp_delvm command
>    migration: improve error reporting for load_vmstate
>    qmp: create QMP implementation of loadvm command
>
>   hmp.c                         | 14 +++++++--
>   include/migration/migration.h |  2 --
>   include/sysemu/sysemu.h       |  2 +-
>   migration/savevm.c            | 56 ++++++++++++++++++++--------------
>   monitor.c                     |  9 +++---
>   qapi-schema.json              | 39 ++++++++++++++++++++++++
>   qmp-commands.hx               | 71 +++++++++++++++++++++++++++++++++++++++++++
>   qmp.c                         |  4 +++
>   vl.c                          |  4 ++-
>   9 files changed, 168 insertions(+), 33 deletions(-)
>
pls disregard this. patch 1 is stale and from the different set.

Sorry :(

[Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Denis V. Lunev]

Unfortunately load_vmstate has a return code (int) and this code is checked
in the other places. Thus we could not just rename it to qmp_loadvm as
returns void.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 migration/savevm.c | 10 ++++++++++
 monitor.c          |  8 ++------
 qapi-schema.json   | 13 +++++++++++++
 qmp-commands.hx    | 23 +++++++++++++++++++++++
 4 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index 3de917e..6b34017 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2096,6 +2096,16 @@ int load_vmstate(const char *name, Error **errp)
     return 0;
 }
 
+void qmp_loadvm(const char *name, Error **errp)
+{
+    int saved_vm_running  = runstate_is_running();
+    vm_stop(RUN_STATE_RESTORE_VM);
+
+    if (load_vmstate(name, errp) == 0 && saved_vm_running) {
+        vm_start();
+    }
+}
+
 void qmp_delvm(const char *name, Error **errp)
 {
     BlockDriverState *bs;
diff --git a/monitor.c b/monitor.c
index 2ddf6c1..c1e998c 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1737,16 +1737,12 @@ void qmp_closefd(const char *fdname, Error **errp)
 
 static void hmp_loadvm(Monitor *mon, const QDict *qdict)
 {
-    int saved_vm_running  = runstate_is_running();
     const char *name = qdict_get_str(qdict, "name");
     Error *local_err = NULL;
 
-    vm_stop(RUN_STATE_RESTORE_VM);
-
-    if (load_vmstate(name, &local_err) < 0) {
+    qmp_loadvm(name, &local_err);
+    if (local_err != NULL) {
         error_report_err(local_err);
-    } else if (saved_vm_running) {
-        vm_start();
     }
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index 94a2764..7d48948 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4080,3 +4080,16 @@
 # Since 2.6
 ##
 { 'command': 'delvm', 'data': {'name': 'str'} }
+
+##
+# @loadvm
+#
+# Load a VM snapshot
+#
+# @name: identifier of a snapshot to be loaded
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'loadvm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 5e6f573..9cd1bfe 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4843,3 +4843,26 @@ EQMP
         .args_type  = "name:s",
         .mhandler.cmd_new = qmp_marshal_delvm,
     },
+
+SQMP
+loadvm
+------
+
+Load a VM snapshot
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "loadvm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "loadvm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_loadvm,
+    },
-- 
2.5.0

Re: [Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Eric Blake]

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On 12/04/2015 07:44 AM, Denis V. Lunev wrote:
> Unfortunately load_vmstate has a return code (int) and this code is checked
> in the other places. Thus we could not just rename it to qmp_loadvm as
> returns void.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Juan Quintela <quintela@redhat.com>
> CC: Amit Shah <amit.shah@redhat.com>
> CC: Markus Armbruster <armbru@redhat.com>
> CC: Eric Blake <eblake@redhat.com>
> ---
>  migration/savevm.c | 12 ++++++++++++
>  monitor.c          | 12 ++++++------
>  qapi-schema.json   | 13 +++++++++++++
>  qmp-commands.hx    | 23 +++++++++++++++++++++++
>  4 files changed, 54 insertions(+), 6 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 7846437..07b0bf4 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2103,6 +2103,18 @@ int load_vmstate(const char *name, Error **errp)
>      return 0;
>  }
>  
> +void qmp_loadvm(const char *name, Error **errp)
> +{
> +    int saved_vm_running  = runstate_is_running();
> +    vm_stop(RUN_STATE_RESTORE_VM);
> +
> +    load_vmstate(name, errp);
> +
> +    if (saved_vm_running) {
> +        vm_start();

Do you really mean to be calling vm_start() even if an error was
reported?  But to properly short-circuit, you need a local 'Error *err =
NULL; load_vmstate(name, &err);', rather than reusing errp (since the
caller may pass in NULL).

> +++ b/monitor.c
> @@ -1737,18 +1737,18 @@ void qmp_closefd(const char *fdname, Error **errp)
>  
>  static void hmp_loadvm(Monitor *mon, const QDict *qdict)
>  {
> -    int saved_vm_running  = runstate_is_running();
>      const char *name = qdict_get_str(qdict, "name");
>      Error *local_err = NULL;
>  
> -    vm_stop(RUN_STATE_RESTORE_VM);
> +    if (name == NULL) {

Dead code.  qdict_get_str() crashes rather than returning NULL, if
"name" is not present.

> +++ b/qmp-commands.hx
> @@ -4787,3 +4787,26 @@ EQMP
>          .args_type  = "name:s",
>          .mhandler.cmd_new = qmp_marshal_delvm,
>      },
> +
> +SQMP
> +loadvm
> +------------------

Line too long.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


[-- Attachment #2: OpenPGP digital signature --]
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[Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Denis V. Lunev]

Unfortunately load_vmstate has a return code (int) and this code is checked
in the other places. Thus we could not just rename it to qmp_loadvm as
returns void.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 migration/savevm.c | 12 ++++++++++++
 monitor.c          | 12 ++++++------
 qapi-schema.json   | 13 +++++++++++++
 qmp-commands.hx    | 23 +++++++++++++++++++++++
 4 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index 7846437..07b0bf4 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2103,6 +2103,18 @@ int load_vmstate(const char *name, Error **errp)
     return 0;
 }
 
+void qmp_loadvm(const char *name, Error **errp)
+{
+    int saved_vm_running  = runstate_is_running();
+    vm_stop(RUN_STATE_RESTORE_VM);
+
+    load_vmstate(name, errp);
+
+    if (saved_vm_running) {
+        vm_start();
+    }
+}
+
 void qmp_delvm(const char *name, Error **errp)
 {
     BlockDriverState *bs;
diff --git a/monitor.c b/monitor.c
index 3857724..aba2c62 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1737,18 +1737,18 @@ void qmp_closefd(const char *fdname, Error **errp)
 
 static void hmp_loadvm(Monitor *mon, const QDict *qdict)
 {
-    int saved_vm_running  = runstate_is_running();
     const char *name = qdict_get_str(qdict, "name");
     Error *local_err = NULL;
 
-    vm_stop(RUN_STATE_RESTORE_VM);
+    if (name == NULL) {
+        monitor_printf(mon, "Snapshot name is not set for hmp_loadvm");
+        return;
+    }
 
-    if (load_vmstate(name, &local_err) < 0) {
+    qmp_loadvm(name, &local_err);
+    if (local_err != NULL) {
         error_report_err(local_err);
     }
-    if (saved_vm_running) {
-        vm_start();
-    }
 }
 
 int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
diff --git a/qapi-schema.json b/qapi-schema.json
index 18c9a6c..9747df8 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3997,3 +3997,16 @@
 # Since 2.6
 ##
 { 'command': 'delvm', 'data': {'name': 'str'} }
+
+##
+# @loadvm
+#
+# Load a VM snapshot
+#
+# @name: identifier of a snapshot to be loaded
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'loadvm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index a630e8a..4dedb62 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4787,3 +4787,26 @@ EQMP
         .args_type  = "name:s",
         .mhandler.cmd_new = qmp_marshal_delvm,
     },
+
+SQMP
+loadvm
+------------------
+
+Load a VM snapshot
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "loadvm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "loadvm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_loadvm,
+    },
-- 
2.5.0

Re: [Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Denis V. Lunev]

On 11/18/2015 02:41 PM, Juan Quintela wrote:
> "Denis V. Lunev" <den@openvz.org> wrote:
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> CC: Juan Quintela <quintela@redhat.com>
>> CC: Amit Shah <amit.shah@redhat.com>
>> CC: Markus Armbruster <armbru@redhat.com>
>> CC: Eric Blake <eblake@redhat.com>
>> ---
>>   migration/savevm.c |  5 +++++
>>   qapi-schema.json   | 13 +++++++++++++
>>   qmp-commands.hx    | 23 +++++++++++++++++++++++
>>   3 files changed, 41 insertions(+)
>>
>> diff --git a/migration/savevm.c b/migration/savevm.c
>> index 08c6c65..f67b5d9 100644
>> --- a/migration/savevm.c
>> +++ b/migration/savevm.c
>> @@ -2116,6 +2116,11 @@ int load_vmstate(const char *name, Error **errp)
>>       return 0;
>>   }
>>   
>> +void qmp_loadvm(const char *name, Error **errp)
>> +{
>> +    load_vmstate(name, errp);
>> +}
>> +
> As Markus suggested for the other functions,  rename load_vmstate qmp_loadvm()
>
> Thanks, Juan.
load_vmstate is actually 'int load_vmstate' and return
code is checked in qemu_img.c

Should I replace error code check there with a check
to *errp != 0 or this would lead us into a problem
with block level guys?

Den

Re: [Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Juan Quintela]

"Denis V. Lunev" <den@openvz.org> wrote:
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Juan Quintela <quintela@redhat.com>
> CC: Amit Shah <amit.shah@redhat.com>
> CC: Markus Armbruster <armbru@redhat.com>
> CC: Eric Blake <eblake@redhat.com>
> ---
>  migration/savevm.c |  5 +++++
>  qapi-schema.json   | 13 +++++++++++++
>  qmp-commands.hx    | 23 +++++++++++++++++++++++
>  3 files changed, 41 insertions(+)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 08c6c65..f67b5d9 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2116,6 +2116,11 @@ int load_vmstate(const char *name, Error **errp)
>      return 0;
>  }
>  
> +void qmp_loadvm(const char *name, Error **errp)
> +{
> +    load_vmstate(name, errp);
> +}
> +

As Markus suggested for the other functions,  rename load_vmstate qmp_loadvm()

Thanks, Juan.

[Qemu-devel] [PATCH 5/5] qmp: create QMP implementation of loadvm command

[Denis V. Lunev]

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Juan Quintela <quintela@redhat.com>
CC: Amit Shah <amit.shah@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
---
 migration/savevm.c |  5 +++++
 qapi-schema.json   | 13 +++++++++++++
 qmp-commands.hx    | 23 +++++++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/migration/savevm.c b/migration/savevm.c
index 08c6c65..f67b5d9 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2116,6 +2116,11 @@ int load_vmstate(const char *name, Error **errp)
     return 0;
 }
 
+void qmp_loadvm(const char *name, Error **errp)
+{
+    load_vmstate(name, errp);
+}
+
 void qmp_delvm(const char *name, Error **errp)
 {
     BlockDriverState *bs;
diff --git a/qapi-schema.json b/qapi-schema.json
index 193b34f..d133711 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3988,3 +3988,16 @@
 # Since 2.6
 ##
 { 'command': 'delvm', 'data': {'name': 'str'} }
+
+##
+# @loadvm
+#
+# Load a VM snapshot
+#
+# @name: identifier of a snapshot to be loaded
+#
+# Returns: Nothing on success
+#
+# Since 2.6
+##
+{ 'command': 'loadvm', 'data': {'name': 'str'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index b2b17ff..d5f80a1 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4787,3 +4787,26 @@ EQMP
         .args_type  = "name:s",
         .mhandler.cmd_new = qmp_marshal_delvm,
     },
+
+SQMP
+loadvm
+------------------
+
+Load a VM snapshot
+
+Arguments:
+
+- "name": snapshot name
+
+Example:
+
+-> { "execute": "loadvm", "arguments": { "name": "snapshot1" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "loadvm",
+        .args_type  = "name:s",
+        .mhandler.cmd_new = qmp_marshal_loadvm,
+    },
-- 
2.5.0