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Re: [Qemu-devel] [PATCH 03/12] migration: create new section to store gl
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 03/12] migration: create new section to store global state |
Date: |
Wed, 1 Jul 2015 10:13:22 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Juan Quintela (address@hidden) wrote:
> This includes a new section that for now just stores the current qemu state.
>
> Right now, there are only one way to control what is the state of the
> target after migration.
>
> - If you run the target qemu with -S, it would start stopped.
> - If you run the target qemu without -S, it would run just after migration
> finishes.
>
> The problem here is what happens if we start the target without -S and
> there happens one error during migration that puts current state as
> -EIO. Migration would ends (notice that the error happend doing block
> IO, network IO, i.e. nothing related with migration), and when
> migration finish, we would just "continue" running on destination,
> probably hanging the guest/corruption data, whatever.
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> include/migration/migration.h | 1 +
> migration/migration.c | 105
> +++++++++++++++++++++++++++++++++++++++---
> trace-events | 3 ++
> vl.c | 1 +
> 4 files changed, 103 insertions(+), 7 deletions(-)
>
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 9387c8c..1280193 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -197,4 +197,5 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t
> block_offset,
>
> void ram_mig_init(void);
> void savevm_skip_section_footers(void);
> +void register_global_state(void);
> #endif
> diff --git a/migration/migration.c b/migration/migration.c
> index c6ac08a..b4b6d69 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -26,6 +26,7 @@
> #include "qemu/thread.h"
> #include "qmp-commands.h"
> #include "trace.h"
> +#include "qapi/util.h"
>
> #define MAX_THROTTLE (32 << 20) /* Migration speed throttling */
>
> @@ -97,6 +98,83 @@ void migration_incoming_state_destroy(void)
> mis_current = NULL;
> }
>
> +
> +typedef struct {
> + uint32_t size;
> + uint8_t runstate[100];
> +} GlobalState;
> +
> +static GlobalState global_state;
> +
> +static int global_state_store(void)
> +{
> + if (!runstate_store((char *)global_state.runstate,
> + sizeof(global_state.runstate))) {
> + trace_migrate_state_too_big();
Hmm ok, but that should have stayed as the error_report - the only
problem with that in the previous version was a \n
(error_report for errors, trace_ for debug)
> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> +static char *global_state_get_runstate(void)
> +{
> + return (char *)global_state.runstate;
> +}
> +
> +static int global_state_post_load(void *opaque, int version_id)
> +{
> + GlobalState *s = opaque;
> + int ret = 0;
> + char *runstate = (char *)s->runstate;
> +
> + trace_migrate_global_state_post_load(runstate);
> +
> + if (strcmp(runstate, "running") != 0) {
> + Error *local_err = NULL;
> + int r = qapi_enum_parse(RunState_lookup, runstate, RUN_STATE_MAX,
> + -1, &local_err);
> +
> + if (r == -1) {
> + if (local_err) {
> + error_report_err(local_err);
> + }
> + return -EINVAL;
> + }
> + ret = vm_stop_force_state(r);
> + }
> +
> + return ret;
> +}
> +
> +static void global_state_pre_save(void *opaque)
> +{
> + GlobalState *s = opaque;
> +
> + trace_migrate_global_state_pre_save((char *)s->runstate);
> + s->size = strlen((char *)s->runstate) + 1;
> + printf("saved state: %s\n", s->runstate);
Stray printf
Other than that,
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> +}
> +
> +static const VMStateDescription vmstate_globalstate = {
> + .name = "globalstate",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .post_load = global_state_post_load,
> + .pre_save = global_state_pre_save,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT32(size, GlobalState),
> + VMSTATE_BUFFER(runstate, GlobalState),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> +void register_global_state(void)
> +{
> + /* We would use it independently that we receive it */
> + strcpy((char *)&global_state.runstate, "");
> + vmstate_register(NULL, 0, &vmstate_globalstate, &global_state);
> +}
> +
> /*
> * Called on -incoming with a defer: uri.
> * The migration can be started later after any parameters have been
> @@ -164,10 +242,20 @@ static void process_incoming_migration_co(void *opaque)
> exit(EXIT_FAILURE);
> }
>
> - if (autostart) {
> + /* runstate == "" means that we haven't received it through the
> + * wire, so we obey autostart. runstate == runing means that we
> + * need to run it, we need to make sure that we do it after
> + * everything else has finished. Every other state change is done
> + * at the post_load function */
> +
> + if (strcmp(global_state_get_runstate(), "running") == 0) {
> vm_start();
> - } else {
> - runstate_set(RUN_STATE_PAUSED);
> + } else if (strcmp(global_state_get_runstate(), "") == 0) {
> + if (autostart) {
> + vm_start();
> + } else {
> + runstate_set(RUN_STATE_PAUSED);
> + }
> }
> migrate_decompress_threads_join();
> }
> @@ -793,10 +881,13 @@ static void *migration_thread(void *opaque)
> qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
> old_vm_running = runstate_is_running();
>
> - ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
> - if (ret >= 0) {
> - qemu_file_set_rate_limit(s->file, INT64_MAX);
> - qemu_savevm_state_complete(s->file);
> + ret = global_state_store();
> + if (!ret) {
> + ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
> + if (ret >= 0) {
> + qemu_file_set_rate_limit(s->file, INT64_MAX);
> + qemu_savevm_state_complete(s->file);
> + }
> }
> qemu_mutex_unlock_iothread();
>
> diff --git a/trace-events b/trace-events
> index 52b7efa..5d5cae2 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1403,6 +1403,9 @@ migrate_fd_error(void) ""
> migrate_fd_cancel(void) ""
> migrate_pending(uint64_t size, uint64_t max) "pending size %" PRIu64 " max
> %" PRIu64
> migrate_transferred(uint64_t tranferred, uint64_t time_spent, double
> bandwidth, uint64_t size) "transferred %" PRIu64 " time_spent %" PRIu64 "
> bandwidth %g max_size %" PRId64
> +migrate_state_too_big(void) ""
> +migrate_global_state_post_load(const char *state) "loaded state: %s"
> +migrate_global_state_pre_save(const char *state) "saved state: %s"
>
> # migration/rdma.c
> qemu_dma_accept_incoming_migration(void) ""
> diff --git a/vl.c b/vl.c
> index d4d9ca8..ce39f60 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -4624,6 +4624,7 @@ int main(int argc, char **argv, char **envp)
> return 0;
> }
>
> + register_global_state();
> if (incoming) {
> Error *local_err = NULL;
> qemu_start_incoming_migration(incoming, &local_err);
> --
> 2.4.3
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH v2 00/12] Migration events + optional sections, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 01/12] runstate: Add runstate store, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 02/12] runstate: migration allows more transitions now, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 03/12] migration: create new section to store global state, Juan Quintela, 2015/07/01
- Re: [Qemu-devel] [PATCH 03/12] migration: create new section to store global state,
Dr. David Alan Gilbert <=
- [Qemu-devel] [PATCH 04/12] global_state: Make section optional, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 05/12] vmstate: Create optional sections, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 06/12] migration: Add configuration section, Juan Quintela, 2015/07/01
- [Qemu-devel] [PATCH 07/12] migration: Use cmpxchg correctly, Juan Quintela, 2015/07/01