On 15/02/2016 13:58, Greg Kurz wrote: > 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 ?
I don't know, but as a user I would like to be able to do that (and it is possible in the other cases). And I think the fix could be smaller: something like just setting "savevm_state.skip_configuration" to the value of "config-section". [I don't know if it is as simple as it looks...] Laurent > >> 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}[,...]] >>> >>> >> >