Patchwork [v8,2/6] Introduce "xen-save-devices-state"

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Submitter Stefano Stabellini
Date March 19, 2012, 11:48 a.m.
Message ID <1332157685-31701-2-git-send-email-stefano.stabellini@eu.citrix.com>
Download mbox | patch
Permalink /patch/147491/
State New
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Stefano Stabellini - March 19, 2012, 11:48 a.m.
- add an "is_ram" flag to SaveStateEntry;

- register_savevm_live sets is_ram for live_savevm devices;

- introduce a "xen-save-devices-state" QAPI command that can be used to save
the state of all devices, but not the RAM or the block devices of the
VM.

Changes in v8:

- rename save-devices-state to xen-save-devices-state.

Changes in v7:

- rename save_devices to save-devices-state.

Changes in v6:

- remove the is_ram parameter from register_savevm_live and sets is_ram
if the device is a live_savevm device;

- introduce save_devices as a QAPI command, write a better description
for it;

- fix CODING_STYLE;

- introduce a new doc to explain the save format used by save_devices.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
---
 docs/xen-save-devices-state.txt |   34 ++++++++++++++++++
 qapi-schema.json                |   19 ++++++++++
 qmp-commands.hx                 |   27 +++++++++++++++
 savevm.c                        |   71 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 151 insertions(+), 0 deletions(-)
 create mode 100644 docs/xen-save-devices-state.txt
Luiz Capitulino - March 19, 2012, 3:02 p.m.
On Mon, 19 Mar 2012 11:48:01 +0000
Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:

> - add an "is_ram" flag to SaveStateEntry;
> 
> - register_savevm_live sets is_ram for live_savevm devices;
> 
> - introduce a "xen-save-devices-state" QAPI command that can be used to save
> the state of all devices, but not the RAM or the block devices of the
> VM.

Is this series expected to go in through the QMP queue?
Stefano Stabellini - March 19, 2012, 3:16 p.m.
On Mon, 19 Mar 2012, Luiz Capitulino wrote:
> > - add an "is_ram" flag to SaveStateEntry;
> > 
> > - register_savevm_live sets is_ram for live_savevm devices;
> > 
> > - introduce a "xen-save-devices-state" QAPI command that can be used to save
> > the state of all devices, but not the RAM or the block devices of the
> > VM.
> 
> Is this series expected to go in through the QMP queue?

That would be OK. Otherwise I was going to submit a pull request to
Anthony as soon as you ack the second patch.
Anthony Liguori - March 19, 2012, 3:24 p.m.
On 03/19/2012 10:16 AM, Stefano Stabellini wrote:
> On Mon, 19 Mar 2012, Luiz Capitulino wrote:
>>> - add an "is_ram" flag to SaveStateEntry;
>>>
>>> - register_savevm_live sets is_ram for live_savevm devices;
>>>
>>> - introduce a "xen-save-devices-state" QAPI command that can be used to save
>>> the state of all devices, but not the RAM or the block devices of the
>>> VM.
>>
>> Is this series expected to go in through the QMP queue?
>
> That would be OK. Otherwise I was going to submit a pull request to
> Anthony as soon as you ack the second patch.

I'd prefer Stefano do a pull request.

I'm happy with the level of reviews to merge this.

Regards,

Anthony Liguori
Luiz Capitulino - March 19, 2012, 3:45 p.m.
On Mon, 19 Mar 2012 11:48:01 +0000
Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:

> - add an "is_ram" flag to SaveStateEntry;
> 
> - register_savevm_live sets is_ram for live_savevm devices;
> 
> - introduce a "xen-save-devices-state" QAPI command that can be used to save
> the state of all devices, but not the RAM or the block devices of the
> VM.
> 
> Changes in v8:
> 
> - rename save-devices-state to xen-save-devices-state.
> 
> Changes in v7:
> 
> - rename save_devices to save-devices-state.
> 
> Changes in v6:
> 
> - remove the is_ram parameter from register_savevm_live and sets is_ram
> if the device is a live_savevm device;
> 
> - introduce save_devices as a QAPI command, write a better description
> for it;
> 
> - fix CODING_STYLE;
> 
> - introduce a new doc to explain the save format used by save_devices.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

Acked-by: Luiz Capitulino <lcapitulino@redhat.com>

> ---
>  docs/xen-save-devices-state.txt |   34 ++++++++++++++++++
>  qapi-schema.json                |   19 ++++++++++
>  qmp-commands.hx                 |   27 +++++++++++++++
>  savevm.c                        |   71 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 151 insertions(+), 0 deletions(-)
>  create mode 100644 docs/xen-save-devices-state.txt
> 
> diff --git a/docs/xen-save-devices-state.txt b/docs/xen-save-devices-state.txt
> new file mode 100644
> index 0000000..92e08db
> --- /dev/null
> +++ b/docs/xen-save-devices-state.txt
> @@ -0,0 +1,34 @@
> += Save Devices =
> +
> +QEMU has code to load/save the state of the guest that it is running.
> +These are two complementary operations.  Saving the state just does
> +that, saves the state for each device that the guest is running.
> +
> +These operations are normally used with migration (see migration.txt),
> +however it is also possible to save the state of all devices to file,
> +without saving the RAM or the block devices of the VM.
> +
> +This operation is called "xen-save-devices-state" (see
> +QMP/qmp-commands.txt)
> +
> +
> +The binary format used in the file is the following:
> +
> +
> +-------------------------------------------
> +
> +32 bit big endian: QEMU_VM_FILE_MAGIC
> +32 bit big endian: QEMU_VM_FILE_VERSION
> +
> +for_each_device
> +{
> +    8 bit:              QEMU_VM_SECTION_FULL
> +    32 bit big endian:  section_id
> +    8 bit:              idstr (ID string) length
> +    string:             idstr (ID string)
> +    32 bit big endian:  instance_id
> +    32 bit big endian:  version_id
> +    buffer:             device specific data
> +}
> +
> +8 bit: QEMU_VM_EOF
> diff --git a/qapi-schema.json b/qapi-schema.json
> index d0b6792..def69a9 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1593,3 +1593,22 @@
>  { 'command': 'qom-list-types',
>    'data': { '*implements': 'str', '*abstract': 'bool' },
>    'returns': [ 'ObjectTypeInfo' ] }
> +
> +##
> +# @xen-save-devices-state:
> +#
> +# Save the state of all devices to file. The RAM and the block devices
> +# of the VM are not saved by this command.
> +#
> +# @filename: the file to save the state of the devices to as binary
> +# data. See xen-save-devices-state.txt for a description of the binary
> +# format.
> +#
> +# Returns: Nothing on success
> +#          If @filename cannot be opened, OpenFileFailed
> +#          If an I/O error occurs while writing the file, IOError
> +#
> +# Since: 1.1
> +##
> +{ 'command': 'xen-save-devices-state', 'data': {'filename': 'str'} }
> +
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 705f704..dbb6236 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -444,6 +444,33 @@ Note: inject-nmi is only supported for x86 guest currently, it will
>  EQMP
>  
>      {
> +        .name       = "xen-save-devices-state",
> +        .args_type  = "filename:F",
> +    .mhandler.cmd_new = qmp_marshal_input_xen_save_devices_state,
> +    },
> +
> +SQMP
> +xen-save-devices-state
> +-------
> +
> +Save the state of all devices to file. The RAM and the block devices
> +of the VM are not saved by this command.
> +
> +Arguments:
> +
> +- "filename": the file to save the state of the devices to as binary
> +data. See xen-save-devices-state.txt for a description of the binary
> +format.
> +
> +Example:
> +
> +-> { "execute": "xen-save-devices-state",
> +     "arguments": { "filename": "/tmp/save" } }
> +<- { "return": {} }
> +
> +EQMP
> +
> +    {
>          .name       = "migrate",
>          .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",
>          .params     = "[-d] [-b] [-i] uri",
> diff --git a/savevm.c b/savevm.c
> index 80be1ff..0e61eb0 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -84,6 +84,7 @@
>  #include "qemu-timer.h"
>  #include "cpus.h"
>  #include "memory.h"
> +#include "qmp-commands.h"
>  
>  #define SELF_ANNOUNCE_ROUNDS 5
>  
> @@ -1177,6 +1178,7 @@ typedef struct SaveStateEntry {
>      void *opaque;
>      CompatEntry *compat;
>      int no_migrate;
> +    int is_ram;
>  } SaveStateEntry;
>  
>  
> @@ -1241,6 +1243,10 @@ int register_savevm_live(DeviceState *dev,
>      se->opaque = opaque;
>      se->vmsd = NULL;
>      se->no_migrate = 0;
> +    /* if this is a live_savem then set is_ram */
> +    if (save_live_state != NULL) {
> +        se->is_ram = 1;
> +    }
>  
>      if (dev && dev->parent_bus && dev->parent_bus->info->get_dev_path) {
>          char *id = dev->parent_bus->info->get_dev_path(dev);
> @@ -1728,6 +1734,45 @@ out:
>      return ret;
>  }
>  
> +static int qemu_save_device_state(QEMUFile *f)
> +{
> +    SaveStateEntry *se;
> +
> +    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
> +    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
> +
> +    cpu_synchronize_all_states();
> +
> +    QTAILQ_FOREACH(se, &savevm_handlers, entry) {
> +        int len;
> +
> +        if (se->is_ram) {
> +            continue;
> +        }
> +        if (se->save_state == NULL && se->vmsd == NULL) {
> +            continue;
> +        }
> +
> +        /* Section type */
> +        qemu_put_byte(f, QEMU_VM_SECTION_FULL);
> +        qemu_put_be32(f, se->section_id);
> +
> +        /* ID string */
> +        len = strlen(se->idstr);
> +        qemu_put_byte(f, len);
> +        qemu_put_buffer(f, (uint8_t *)se->idstr, len);
> +
> +        qemu_put_be32(f, se->instance_id);
> +        qemu_put_be32(f, se->version_id);
> +
> +        vmstate_save(f, se);
> +    }
> +
> +    qemu_put_byte(f, QEMU_VM_EOF);
> +
> +    return qemu_file_get_error(f);
> +}
> +
>  static SaveStateEntry *find_se(const char *idstr, int instance_id)
>  {
>      SaveStateEntry *se;
> @@ -2109,6 +2154,32 @@ void do_savevm(Monitor *mon, const QDict *qdict)
>          vm_start();
>  }
>  
> +void qmp_xen_save_devices_state(const char *filename, Error **errp)
> +{
> +    QEMUFile *f;
> +    int saved_vm_running;
> +    int ret;
> +
> +    saved_vm_running = runstate_is_running();
> +    vm_stop(RUN_STATE_SAVE_VM);
> +
> +    f = qemu_fopen(filename, "wb");
> +    if (!f) {
> +        error_set(errp, QERR_OPEN_FILE_FAILED, filename);
> +        goto the_end;
> +    }
> +    ret = qemu_save_device_state(f);
> +    qemu_fclose(f);
> +    if (ret < 0) {
> +        error_set(errp, QERR_IO_ERROR);
> +    }
> +
> + the_end:
> +    if (saved_vm_running)
> +        vm_start();
> +    return;
> +}
> +
>  int load_vmstate(const char *name)
>  {
>      BlockDriverState *bs, *bs_vm_state;
Stefano Stabellini - March 19, 2012, 6:32 p.m.
On Mon, 19 Mar 2012, Luiz Capitulino wrote:
> On Mon, 19 Mar 2012 11:48:01 +0000
> Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:
> 
> > - add an "is_ram" flag to SaveStateEntry;
> > 
> > - register_savevm_live sets is_ram for live_savevm devices;
> > 
> > - introduce a "xen-save-devices-state" QAPI command that can be used to save
> > the state of all devices, but not the RAM or the block devices of the
> > VM.
> > 
> > Changes in v8:
> > 
> > - rename save-devices-state to xen-save-devices-state.
> > 
> > Changes in v7:
> > 
> > - rename save_devices to save-devices-state.
> > 
> > Changes in v6:
> > 
> > - remove the is_ram parameter from register_savevm_live and sets is_ram
> > if the device is a live_savevm device;
> > 
> > - introduce save_devices as a QAPI command, write a better description
> > for it;
> > 
> > - fix CODING_STYLE;
> > 
> > - introduce a new doc to explain the save format used by save_devices.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
> 
> Acked-by: Luiz Capitulino <lcapitulino@redhat.com>

Thanks!
Stefano Stabellini - March 19, 2012, 6:38 p.m.
On Mon, 19 Mar 2012, Anthony Liguori wrote:
> On 03/19/2012 10:16 AM, Stefano Stabellini wrote:
> > On Mon, 19 Mar 2012, Luiz Capitulino wrote:
> >>> - add an "is_ram" flag to SaveStateEntry;
> >>>
> >>> - register_savevm_live sets is_ram for live_savevm devices;
> >>>
> >>> - introduce a "xen-save-devices-state" QAPI command that can be used to save
> >>> the state of all devices, but not the RAM or the block devices of the
> >>> VM.
> >>
> >> Is this series expected to go in through the QMP queue?
> >
> > That would be OK. Otherwise I was going to submit a pull request to
> > Anthony as soon as you ack the second patch.
> 
> I'd prefer Stefano do a pull request.
> 
> I'm happy with the level of reviews to merge this.

Done

Patch

diff --git a/docs/xen-save-devices-state.txt b/docs/xen-save-devices-state.txt
new file mode 100644
index 0000000..92e08db
--- /dev/null
+++ b/docs/xen-save-devices-state.txt
@@ -0,0 +1,34 @@ 
+= Save Devices =
+
+QEMU has code to load/save the state of the guest that it is running.
+These are two complementary operations.  Saving the state just does
+that, saves the state for each device that the guest is running.
+
+These operations are normally used with migration (see migration.txt),
+however it is also possible to save the state of all devices to file,
+without saving the RAM or the block devices of the VM.
+
+This operation is called "xen-save-devices-state" (see
+QMP/qmp-commands.txt)
+
+
+The binary format used in the file is the following:
+
+
+-------------------------------------------
+
+32 bit big endian: QEMU_VM_FILE_MAGIC
+32 bit big endian: QEMU_VM_FILE_VERSION
+
+for_each_device
+{
+    8 bit:              QEMU_VM_SECTION_FULL
+    32 bit big endian:  section_id
+    8 bit:              idstr (ID string) length
+    string:             idstr (ID string)
+    32 bit big endian:  instance_id
+    32 bit big endian:  version_id
+    buffer:             device specific data
+}
+
+8 bit: QEMU_VM_EOF
diff --git a/qapi-schema.json b/qapi-schema.json
index d0b6792..def69a9 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1593,3 +1593,22 @@ 
 { 'command': 'qom-list-types',
   'data': { '*implements': 'str', '*abstract': 'bool' },
   'returns': [ 'ObjectTypeInfo' ] }
+
+##
+# @xen-save-devices-state:
+#
+# Save the state of all devices to file. The RAM and the block devices
+# of the VM are not saved by this command.
+#
+# @filename: the file to save the state of the devices to as binary
+# data. See xen-save-devices-state.txt for a description of the binary
+# format.
+#
+# Returns: Nothing on success
+#          If @filename cannot be opened, OpenFileFailed
+#          If an I/O error occurs while writing the file, IOError
+#
+# Since: 1.1
+##
+{ 'command': 'xen-save-devices-state', 'data': {'filename': 'str'} }
+
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 705f704..dbb6236 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -444,6 +444,33 @@  Note: inject-nmi is only supported for x86 guest currently, it will
 EQMP
 
     {
+        .name       = "xen-save-devices-state",
+        .args_type  = "filename:F",
+    .mhandler.cmd_new = qmp_marshal_input_xen_save_devices_state,
+    },
+
+SQMP
+xen-save-devices-state
+-------
+
+Save the state of all devices to file. The RAM and the block devices
+of the VM are not saved by this command.
+
+Arguments:
+
+- "filename": the file to save the state of the devices to as binary
+data. See xen-save-devices-state.txt for a description of the binary
+format.
+
+Example:
+
+-> { "execute": "xen-save-devices-state",
+     "arguments": { "filename": "/tmp/save" } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "migrate",
         .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",
         .params     = "[-d] [-b] [-i] uri",
diff --git a/savevm.c b/savevm.c
index 80be1ff..0e61eb0 100644
--- a/savevm.c
+++ b/savevm.c
@@ -84,6 +84,7 @@ 
 #include "qemu-timer.h"
 #include "cpus.h"
 #include "memory.h"
+#include "qmp-commands.h"
 
 #define SELF_ANNOUNCE_ROUNDS 5
 
@@ -1177,6 +1178,7 @@  typedef struct SaveStateEntry {
     void *opaque;
     CompatEntry *compat;
     int no_migrate;
+    int is_ram;
 } SaveStateEntry;
 
 
@@ -1241,6 +1243,10 @@  int register_savevm_live(DeviceState *dev,
     se->opaque = opaque;
     se->vmsd = NULL;
     se->no_migrate = 0;
+    /* if this is a live_savem then set is_ram */
+    if (save_live_state != NULL) {
+        se->is_ram = 1;
+    }
 
     if (dev && dev->parent_bus && dev->parent_bus->info->get_dev_path) {
         char *id = dev->parent_bus->info->get_dev_path(dev);
@@ -1728,6 +1734,45 @@  out:
     return ret;
 }
 
+static int qemu_save_device_state(QEMUFile *f)
+{
+    SaveStateEntry *se;
+
+    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
+    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
+
+    cpu_synchronize_all_states();
+
+    QTAILQ_FOREACH(se, &savevm_handlers, entry) {
+        int len;
+
+        if (se->is_ram) {
+            continue;
+        }
+        if (se->save_state == NULL && se->vmsd == NULL) {
+            continue;
+        }
+
+        /* Section type */
+        qemu_put_byte(f, QEMU_VM_SECTION_FULL);
+        qemu_put_be32(f, se->section_id);
+
+        /* ID string */
+        len = strlen(se->idstr);
+        qemu_put_byte(f, len);
+        qemu_put_buffer(f, (uint8_t *)se->idstr, len);
+
+        qemu_put_be32(f, se->instance_id);
+        qemu_put_be32(f, se->version_id);
+
+        vmstate_save(f, se);
+    }
+
+    qemu_put_byte(f, QEMU_VM_EOF);
+
+    return qemu_file_get_error(f);
+}
+
 static SaveStateEntry *find_se(const char *idstr, int instance_id)
 {
     SaveStateEntry *se;
@@ -2109,6 +2154,32 @@  void do_savevm(Monitor *mon, const QDict *qdict)
         vm_start();
 }
 
+void qmp_xen_save_devices_state(const char *filename, Error **errp)
+{
+    QEMUFile *f;
+    int saved_vm_running;
+    int ret;
+
+    saved_vm_running = runstate_is_running();
+    vm_stop(RUN_STATE_SAVE_VM);
+
+    f = qemu_fopen(filename, "wb");
+    if (!f) {
+        error_set(errp, QERR_OPEN_FILE_FAILED, filename);
+        goto the_end;
+    }
+    ret = qemu_save_device_state(f);
+    qemu_fclose(f);
+    if (ret < 0) {
+        error_set(errp, QERR_IO_ERROR);
+    }
+
+ the_end:
+    if (saved_vm_running)
+        vm_start();
+    return;
+}
+
 int load_vmstate(const char *name)
 {
     BlockDriverState *bs, *bs_vm_state;