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Re: [Qemu-devel] [PATCH RESEND v5 2/6] Introduce "save_devices"
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH RESEND v5 2/6] Introduce "save_devices" |
Date: |
Tue, 13 Mar 2012 11:51:56 +0000 |
User-agent: |
Alpine 2.00 (DEB 1167 2008-08-23) |
On Mon, 12 Mar 2012, Anthony Liguori wrote:
> On 02/28/2012 09:51 AM, Stefano Stabellini wrote:
> > - add an "is_ram" flag to SaveStateEntry;
> >
> > - add an "is_ram" parameter to register_savevm_live;
> >
> > - introduce a "save_devices" monitor command that can be used to save
> > the state of non-ram devices.
> >
> > Signed-off-by: Stefano Stabellini<address@hidden>
> > ---
> > block-migration.c | 2 +-
> > hmp-commands.hx | 14 ++++++++++
> > qmp-commands.hx | 17 ++++++++++++
> > savevm.c | 72
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> > sysemu.h | 1 +
> > vl.c | 2 +-
> > vmstate.h | 1 +
> > 7 files changed, 106 insertions(+), 3 deletions(-)
> >
> > diff --git a/block-migration.c b/block-migration.c
> > index 4467468..d283fd0 100644
> > --- a/block-migration.c
> > +++ b/block-migration.c
> > @@ -722,6 +722,6 @@ void blk_mig_init(void)
> > QSIMPLEQ_INIT(&block_mig_state.bmds_list);
> > QSIMPLEQ_INIT(&block_mig_state.blk_list);
> >
> > - register_savevm_live(NULL, "block", 0, 1, block_set_params,
> > + register_savevm_live(NULL, "block", 0, 1, 0, block_set_params,
> > block_save_live, NULL,
> > block_load,&block_mig_state);
>
> Do you really want the block live migration to be part of Xen?
>
> If not, then you can simplify by just making register_savevm_live always
> imply
> !device and adjust register_savevm() accordingly. Otherwise, the likelihood
> of
> a casual observer knowing what '0, 1, 0' means is pretty bad...
That's a good point, I'll do that.
> > }
> > diff --git a/hmp-commands.hx b/hmp-commands.hx
> > index 64b3656..873abc9 100644
> > --- a/hmp-commands.hx
> > +++ b/hmp-commands.hx
> > @@ -280,6 +280,20 @@ a snapshot with the same tag or ID, it is replaced.
> > More info at
> > ETEXI
> >
> > {
> > + .name = "save_devices",
> > + .args_type = "filename:F",
> > + .params = "filename",
> > + .help = "save the state of non-ram devices.",
> > + .mhandler.cmd_new = do_save_device_state,
> > + },
> > +
> > +STEXI
> > address@hidden save_devices @var{filename}
> > address@hidden save_devices
> > +Save the state of non-ram devices.
> > +ETEXI
> > +
> > + {
> > .name = "loadvm",
> > .args_type = "name:s",
> > .params = "tag|id",
> > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > index 705f704..619d9de 100644
> > --- a/qmp-commands.hx
> > +++ b/qmp-commands.hx
> > @@ -444,6 +444,23 @@ Note: inject-nmi is only supported for x86 guest
> > currently, it will
> > EQMP
> >
> > {
> > + .name = "save_devices",
> > + .args_type = "filename:F",
> > + .params = "filename",
> > + .help = "save the state of non-ram devices.",
> > + .user_print = monitor_user_noop,
> > + .mhandler.cmd_new = do_save_device_state,
> > + },
> > +
> > +SQMP
> > +save_devices
> > +-------
> > +
> > +Save the state of non-ram devices.
> > +
> > +EQMP
> > +
> > + {
> > .name = "migrate",
> > .args_type = "detach:-d,blk:-b,inc:-i,uri:s",
> > .params = "[-d] [-b] [-i] uri",
>
>
> Should be QAPI commands and documented a great deal more (see other examples
> in
> qapi-schema.json). Please CC Luiz too when adding new QMP commands.
OK, I'll do.
> > diff --git a/savevm.c b/savevm.c
> > index 80be1ff..d0e62bb 100644
> > --- a/savevm.c
> > +++ b/savevm.c
> > @@ -1177,6 +1177,7 @@ typedef struct SaveStateEntry {
> > void *opaque;
> > CompatEntry *compat;
> > int no_migrate;
> > + int is_ram;
> > } SaveStateEntry;
> >
> >
> > @@ -1223,6 +1224,7 @@ int register_savevm_live(DeviceState *dev,
> > const char *idstr,
> > int instance_id,
> > int version_id,
> > + int is_ram,
> > SaveSetParamsHandler *set_params,
> > SaveLiveStateHandler *save_live_state,
> > SaveStateHandler *save_state,
> > @@ -1241,6 +1243,7 @@ int register_savevm_live(DeviceState *dev,
> > se->opaque = opaque;
> > se->vmsd = NULL;
> > se->no_migrate = 0;
> > + se->is_ram = is_ram;
> >
> > if (dev&& dev->parent_bus&& dev->parent_bus->info->get_dev_path) {
> > char *id = dev->parent_bus->info->get_dev_path(dev);
> > @@ -1277,7 +1280,7 @@ int register_savevm(DeviceState *dev,
> > LoadStateHandler *load_state,
> > void *opaque)
> > {
> > - return register_savevm_live(dev, idstr, instance_id, version_id,
> > + return register_savevm_live(dev, idstr, instance_id, version_id, 0,
> > NULL, NULL, save_state, load_state,
> > opaque);
> > }
> >
> > @@ -1728,6 +1731,43 @@ out:
> > return ret;
> > }
> >
> > +static int qemu_save_device_state(Monitor *mon, 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;
>
> Violating CODING_STYLE.
I'll fix that.
> > + 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);
> > +}
>
> Please add something to docs/ documenting this format.
OK
> > +
> > static SaveStateEntry *find_se(const char *idstr, int instance_id)
> > {
> > SaveStateEntry *se;
> > @@ -2109,6 +2149,36 @@ void do_savevm(Monitor *mon, const QDict *qdict)
> > vm_start();
> > }
> >
> > +int do_save_device_state(Monitor *mon, const QDict *qdict, QObject
> > **ret_data)
> > +{
> > + int ret;
> > + QEMUFile *f;
> > + int saved_vm_running;
> > + const char *filename = qdict_get_try_str(qdict, "filename");
> > +
> > + saved_vm_running = runstate_is_running();
> > + vm_stop(RUN_STATE_SAVE_VM);
> > +
> > + f = qemu_fopen(filename, "wb");
> > + if (!f) {
> > + monitor_printf(mon, "Could not open VM state file\n");
> > + ret = -1;
> > + goto the_end;
> > + }
> > + ret = qemu_save_device_state(mon, f);
> > + qemu_fclose(f);
> > + if (ret< 0) {
> > + monitor_printf(mon, "Error %d while writing VM\n", ret);
> > + goto the_end;
> > + }
> > + ret = 0;
> > +
> > + the_end:
> > + if (saved_vm_running)
> > + vm_start();
> > + return ret;
> > +}
> > +
>
> Would it be useful/interesting to return a binary blob via QMP instead of
> writing to a file?
Yes, it is potentially useful. I have just gone with the file interface
because it is easier to handle but I could change it or maybe have QMP
return the binary as an alternative option.