Re: [Qemu-devel] [PATCH COLO-Frame v9 03/32] COLO: migrate colo related info to slave

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> We can know if VM in destination should go into COLO mode by refer to
> the info that been migrated from PVM.
> 
> We skip this section if colo is not enabled (i.e.
> migrate_set_capability colo off), so that, It not break compatibility with migration
> however the --enable-colo/disable-colo on the source/destination;
> 
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>  include/migration/colo.h |  2 ++
>  migration/Makefile.objs  |  1 +
>  migration/colo-comm.c    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
>  vl.c                     |  3 ++-
>  4 files changed, 59 insertions(+), 1 deletion(-)
>  create mode 100644 migration/colo-comm.c
> 
> diff --git a/include/migration/colo.h b/include/migration/colo.h
> index c60a590..9b6662d 100644
> --- a/include/migration/colo.h
> +++ b/include/migration/colo.h
> @@ -14,7 +14,9 @@
>  #define QEMU_COLO_H
>  
>  #include "qemu-common.h"
> +#include "migration/migration.h"
>  
>  bool colo_supported(void);
> +void colo_info_mig_init(void);
>  
>  #endif
> diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> index 5a25d39..cb7bd30 100644
> --- a/migration/Makefile.objs
> +++ b/migration/Makefile.objs
> @@ -1,5 +1,6 @@
>  common-obj-y += migration.o tcp.o
>  common-obj-$(CONFIG_COLO) += colo.o
> +common-obj-y += colo-comm.o
>  common-obj-y += vmstate.o
>  common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
>  common-obj-y += xbzrle.o
> diff --git a/migration/colo-comm.c b/migration/colo-comm.c
> new file mode 100644
> index 0000000..4330bd8
> --- /dev/null
> +++ b/migration/colo-comm.c
> @@ -0,0 +1,54 @@
> +/*
> + * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
> + * (a.k.a. Fault Tolerance or Continuous Replication)
> + *
> + * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
> + * Copyright (c) 2015 FUJITSU LIMITED
> + * Copyright (c) 2015 Intel Corporation
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * later. See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include <migration/colo.h>
> +#include "trace.h"
> +
> +typedef struct {
> +     uint32_t colo_requested;
> +} COLOInfo;
> +
> +static COLOInfo colo_info;
> +
> +static void colo_info_pre_save(void *opaque)
> +{
> +    COLOInfo *s = opaque;
> +
> +    if (migrate_enable_colo()) {
> +        s->colo_requested = 1;
> +    } else {
> +        s->colo_requested = 0;
> +    }
> +}
> +
> +static bool colo_info_need(void *opaque)
> +{
> +   return migrate_enable_colo();
> +}
> +
> +static const VMStateDescription colo_state = {
> +     .name = "COLOState",
> +     .version_id = 1,
> +     .minimum_version_id = 1,
> +     .pre_save = colo_info_pre_save,
> +     .needed = colo_info_need,
> +     .fields = (VMStateField[]) {
> +         VMSTATE_UINT32(colo_requested, COLOInfo),

Any reason not to do it as a bool, and use VMSTATE_BOOL?
(That would also simplify the pre_save).

(Oddly you don't actually need the state at all - just
the presence of the section is enough, but I don't worry
about that).

Dave

> +         VMSTATE_END_OF_LIST()
> +        },
> +};
> +
> +void colo_info_mig_init(void)
> +{
> +    vmstate_register(NULL, 0, &colo_state, &colo_info);
> +}
> diff --git a/vl.c b/vl.c
> index aee931a..571347a 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -92,6 +92,7 @@ int main(int argc, char **argv)
>  #include "sysemu/dma.h"
>  #include "audio/audio.h"
>  #include "migration/migration.h"
> +#include "migration/colo.h"
>  #include "sysemu/kvm.h"
>  #include "qapi/qmp/qjson.h"
>  #include "qemu/option.h"
> @@ -4446,7 +4447,7 @@ int main(int argc, char **argv, char **envp)
>  
>      blk_mig_init();
>      ram_mig_init();
> -
> +    colo_info_mig_init();
>      /* If the currently selected machine wishes to override the units-per-bus
>       * property of its default HBA interface type, do so now. */
>      if (machine_class->units_per_default_bus) {
> -- 
> 1.8.3.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK