On Mon, 15 Feb 2016 12:23:39 +0100
Laurent Vivier <lviv...@redhat.com> wrote:
> On 15/02/2016 11:15, Greg Kurz wrote:
> > Since QEMU 2.4, the migration stream begins with a configuration section.
> > It is known to break migration of pseries machine from older QEMU. It is
> > possible to fix this in the pseries compat code but it will then break
> > migration of old pseries from latest QEMU.
> >
> > As an alternative, this patch introduces a new machine property which
> > allows to ignore the abscence of configuration section during incoming
> > migration. It boils to adding:
> >
> > -machine config-section=off
> >
> > Using this property only makes sense when migrating from an older
> > QEMU. It has no effect on outgoing migration.
>
> I think this is not true: migrating a pseries-2.3 machine from a
> qemu-2.4 to a qemu-2.3 must not send the configuration section because
> the qemu-2.3 will not be able to decode it.
>
I did not mind to also fix backward compatibility... is it mandatory ?
> 2016-02-15T11:22:08.645978Z qemu-system-ppc64: Unknown savevm section type 7
> 2016-02-15T11:22:08.646041Z qemu-system-ppc64: load of migration failed:
> Invalid argument
>
> [This is the result without your patch]
>
> Laurent
> >
> > Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> > Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
> > ---
> > hw/core/machine.c | 21 +++++++++++++++++++++
> > include/hw/boards.h | 1 +
> > migration/savevm.c | 21 +++++++++++++++------
> > qemu-options.hx | 3 ++-
> > 4 files changed, 39 insertions(+), 7 deletions(-)
> >
> > diff --git a/hw/core/machine.c b/hw/core/machine.c
> > index 6d1a0d8eebc4..4a7322988fb5 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -312,6 +312,20 @@ static bool machine_get_suppress_vmdesc(Object *obj,
> > Error **errp)
> > return ms->suppress_vmdesc;
> > }
> >
> > +static void machine_set_config_section(Object *obj, bool value, Error
> > **errp)
> > +{
> > + MachineState *ms = MACHINE(obj);
> > +
> > + ms->config_section = value;
> > +}
> > +
> > +static bool machine_get_config_section(Object *obj, Error **errp)
> > +{
> > + MachineState *ms = MACHINE(obj);
> > +
> > + return ms->config_section;
> > +}
> > +
> > static int error_on_sysbus_device(SysBusDevice *sbdev, void *opaque)
> > {
> > error_report("Option '-device %s' cannot be handled by this machine",
> > @@ -365,6 +379,7 @@ static void machine_initfn(Object *obj)
> > ms->kvm_shadow_mem = -1;
> > ms->dump_guest_core = true;
> > ms->mem_merge = true;
> > + ms->config_section = true;
> >
> > object_property_add_str(obj, "accel",
> > machine_get_accel, machine_set_accel, NULL);
> > @@ -467,6 +482,12 @@ static void machine_initfn(Object *obj)
> > object_property_set_description(obj, "suppress-vmdesc",
> > "Set on to disable self-describing
> > migration",
> > NULL);
> > + object_property_add_bool(obj, "config-section",
> > + machine_get_config_section,
> > + machine_set_config_section, NULL);
> > + object_property_set_description(obj, "config-section",
> > + "Set on/off to accept migration
> > with/without configuration section",
> > + NULL);
> >
> > /* Register notifier when init is done for sysbus sanity checks */
> > ms->sysbus_notifier.notify = machine_init_notify;
> > diff --git a/include/hw/boards.h b/include/hw/boards.h
> > index 0f30959e2e3b..853bb5905ec1 100644
> > --- a/include/hw/boards.h
> > +++ b/include/hw/boards.h
> > @@ -128,6 +128,7 @@ struct MachineState {
> > char *firmware;
> > bool iommu;
> > bool suppress_vmdesc;
> > + bool config_section;
> >
> > ram_addr_t ram_size;
> > ram_addr_t maxram_size;
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index 94f2894243ce..3795489aeaec 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -1847,6 +1847,12 @@ static int qemu_loadvm_state_main(QEMUFile *f,
> > MigrationIncomingState *mis)
> > return 0;
> > }
> >
> > +static bool must_receive_configuration(void)
> > +{
> > + MachineState *machine = MACHINE(qdev_get_machine());
> > + return machine->config_section;
> > +}
> > +
> > int qemu_loadvm_state(QEMUFile *f)
> > {
> > MigrationIncomingState *mis = migration_incoming_get_current();
> > @@ -1876,15 +1882,18 @@ int qemu_loadvm_state(QEMUFile *f)
> > }
> >
> > if (!savevm_state.skip_configuration) {
> > - if (qemu_get_byte(f) != QEMU_VM_CONFIGURATION) {
> > + if (qemu_peek_byte(f, 0) == QEMU_VM_CONFIGURATION) {
> > + qemu_file_skip(f, 1);
> > + ret = vmstate_load_state(f, &vmstate_configuration,
> > &savevm_state,
> > + 0);
> > +
> > + if (ret) {
> > + return ret;
> > + }
> > + } else if (must_receive_configuration()) {
> > error_report("Configuration section missing");
> > return -EINVAL;
> > }
> > - ret = vmstate_load_state(f, &vmstate_configuration, &savevm_state,
> > 0);
> > -
> > - if (ret) {
> > - return ret;
> > - }
> > }
> >
> > ret = qemu_loadvm_state_main(f, mis);
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 2f0465eeb1d1..10cd64dc266b 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -43,7 +43,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
> > " aes-key-wrap=on|off controls support for AES key
> > wrapping (default=on)\n"
> > " dea-key-wrap=on|off controls support for DEA key
> > wrapping (default=on)\n"
> > " suppress-vmdesc=on|off disables self-describing
> > migration (default=off)\n"
> > - " nvdimm=on|off controls NVDIMM support
> > (default=off)\n",
> > + " nvdimm=on|off controls NVDIMM support (default=off)\n"
> > + " config-section=on|off migration requires
> > configuration section (default=on)\n",
> > QEMU_ARCH_ALL)
> > STEXI
> > @item -machine [type=]@var{name}[,prop=@var{value}[,...]]
> >
> >
>
