* zhanghailiang (zhang.zhanghaili...@huawei.com) wrote:
> We need communications protocol of user-defined to control the checkpoint
> process.
>
> The new checkpoint request is started by Primary VM, and the interactive
> process
> like below:
> Checkpoint synchronizing points:
>
> Primary Secondary
> initial work
> 'checkpoint-ready' <-------------------- @
>
> 'checkpoint-request' @ -------------------->
> Suspend (Only in hybrid mode)
> 'checkpoint-reply' <-------------------- @
> Suspend&Save state
> 'vmstate-send' @ -------------------->
> Send state Receive state
> 'vmstate-received' <-------------------- @
> Release packets Load state
> 'vmstate-load' <-------------------- @
> Resume Resume (Only in hybrid mode)
>
> Start Comparing (Only in hybrid mode)
> NOTE:
> 1) '@' who sends the message
> 2) Every sync-point is synchronized by two sides with only
> one handshake(single direction) for low-latency.
> If more strict synchronization is required, a opposite direction
> sync-point should be added.
> 3) Since sync-points are single direction, the remote side may
> go forward a lot when this side just receives the sync-point.
> 4) For now, we only support 'periodic' checkpoint, for which
> the Secondary VM is not running, later we will support 'hybrid' mode.
>
> Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
> Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
> Signed-off-by: Gonglei <arei.gong...@huawei.com>
> Cc: Eric Blake <ebl...@redhat.com>
> Cc: Markus Armbruster <arm...@redhat.com>
> Cc: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> v13:
> - Refactor colo command related helper functions, use 'Error **errp' parameter
> instead of return value to indicate success or failure.
> - Fix some other comments from Markus.
>
> v12:
> - Rename colo_ctl_put() to colo_put_cmd()
> - Rename colo_ctl_get() to colo_get_check_cmd() and drop
> the third parameter
> - Rename colo_ctl_get_cmd() to colo_get_cmd()
> - Remove useless 'invalid' member for COLOcommand enum.
> v11:
> - Add missing 'checkpoint-ready' communication in comment.
> - Use parameter to return 'value' for colo_ctl_get() (Dave's suggestion)
> - Fix trace for colo_ctl_get() to trace command and value both
> v10:
> - Rename enum COLOCmd to COLOCommand (Eric's suggestion).
> - Remove unused 'ram-steal'
> ---
> migration/colo.c | 201
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> qapi-schema.json | 25 +++++++
> trace-events | 2 +
> 3 files changed, 226 insertions(+), 2 deletions(-)
>
> diff --git a/migration/colo.c b/migration/colo.c
> index 65ac0c9..c76e1fa 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -10,6 +10,7 @@
> * later. See the COPYING file in the top-level directory.
> */
>
> +#include <unistd.h>
> #include "sysemu/sysemu.h"
> #include "migration/colo.h"
> #include "trace.h"
> @@ -34,22 +35,147 @@ bool migration_incoming_in_colo_state(void)
> return mis && (mis->state == MIGRATION_STATUS_COLO);
> }
>
> +static void colo_put_cmd(QEMUFile *f, COLOCommand cmd,
> + Error **errp)
> +{
> + int ret;
> +
> + if (cmd >= COLO_COMMAND__MAX) {
> + error_setg(errp, "%s: Invalid cmd", __func__);
> + return;
> + }
> + qemu_put_be32(f, cmd);
> + qemu_fflush(f);
> +
> + ret = qemu_file_get_error(f);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Can't put COLO command");
> + }
> + trace_colo_put_cmd(COLOCommand_lookup[cmd]);
> +}
> +
> +static COLOCommand colo_get_cmd(QEMUFile *f, Error **errp)
> +{
> + COLOCommand cmd;
> + int ret;
> +
> + cmd = qemu_get_be32(f);
> + ret = qemu_file_get_error(f);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Can't get COLO command");
> + return cmd;
> + }
> + if (cmd >= COLO_COMMAND__MAX) {
I'm not sure this is guaranteed to do the right thing if the value
read was negative and converted to the enum; it seems to depend
a bit on the compiler as to whether an enum is signed or not;
but it seems the normal behaviour is for the enum to be unsigned
as long as there are no negative values when it's declared; so it looks
safe in practice.
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> + error_setg(errp, "%s: Invalid cmd", __func__);
> + return cmd;
> + }
> + trace_colo_get_cmd(COLOCommand_lookup[cmd]);
> + return cmd;
> +}
> +
> +static void colo_get_check_cmd(QEMUFile *f, COLOCommand expect_cmd,
> + Error **errp)
> +{
> + COLOCommand cmd;
> + Error *local_err = NULL;
> +
> + cmd = colo_get_cmd(f, &local_err);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return;
> + }
> + if (cmd != expect_cmd) {
> + error_setg(errp, "Unexpected COLO command %d, expected %d",
> + expect_cmd, cmd);
> + }
> +}
> +
> +static int colo_do_checkpoint_transaction(MigrationState *s)
> +{
> + Error *local_err = NULL;
> +
> + colo_put_cmd(s->to_dst_file, COLO_COMMAND_CHECKPOINT_REQUEST,
> + &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + colo_get_check_cmd(s->rp_state.from_dst_file,
> + COLO_COMMAND_CHECKPOINT_REPLY, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + /* TODO: suspend and save vm state to colo buffer */
> +
> + colo_put_cmd(s->to_dst_file, COLO_COMMAND_VMSTATE_SEND, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + /* TODO: send vmstate to Secondary */
> +
> + colo_get_check_cmd(s->rp_state.from_dst_file,
> + COLO_COMMAND_VMSTATE_RECEIVED, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + colo_get_check_cmd(s->rp_state.from_dst_file,
> + COLO_COMMAND_VMSTATE_LOADED, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + /* TODO: resume Primary */
> +
> + return 0;
> +out:
> + if (local_err) {
> + error_report_err(local_err);
> + }
> + return -EINVAL;
> +}
> +
> static void colo_process_checkpoint(MigrationState *s)
> {
> + Error *local_err = NULL;
> + int ret;
> +
> s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
> if (!s->rp_state.from_dst_file) {
> error_report("Open QEMUFile from_dst_file failed");
> goto out;
> }
>
> + /*
> + * Wait for Secondary finish loading vm states and enter COLO
> + * restore.
> + */
> + colo_get_check_cmd(s->rp_state.from_dst_file,
> + COLO_COMMAND_CHECKPOINT_READY, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> qemu_mutex_lock_iothread();
> vm_start();
> qemu_mutex_unlock_iothread();
> trace_colo_vm_state_change("stop", "run");
>
> - /*TODO: COLO checkpoint savevm loop*/
> + while (s->state == MIGRATION_STATUS_COLO) {
> + /* start a colo checkpoint */
> + ret = colo_do_checkpoint_transaction(s);
> + if (ret < 0) {
> + goto out;
> + }
> + }
>
> out:
> + /* Throw the unreported error message after exited from loop */
> + if (local_err) {
> + error_report_err(local_err);
> + }
> migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
> MIGRATION_STATUS_COMPLETED);
>
> @@ -67,9 +193,33 @@ void migrate_start_colo_process(MigrationState *s)
> qemu_mutex_lock_iothread();
> }
>
> +static void colo_wait_handle_cmd(QEMUFile *f, int *checkpoint_request,
> + Error **errp)
> +{
> + COLOCommand cmd;
> + Error *local_err = NULL;
> +
> + cmd = colo_get_cmd(f, &local_err);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return;
> + }
> +
> + switch (cmd) {
> + case COLO_COMMAND_CHECKPOINT_REQUEST:
> + *checkpoint_request = 1;
> + break;
> + default:
> + *checkpoint_request = 0;
> + error_setg(errp, "Got unknown COLO command: %d", cmd);
> + break;
> + }
> +}
> +
> void *colo_process_incoming_thread(void *opaque)
> {
> MigrationIncomingState *mis = opaque;
> + Error *local_err = NULL;
>
> migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
> MIGRATION_STATUS_COLO);
> @@ -85,9 +235,56 @@ void *colo_process_incoming_thread(void *opaque)
> */
> qemu_file_set_blocking(mis->from_src_file, true);
>
> - /* TODO: COLO checkpoint restore loop */
> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_CHECKPOINT_READY,
> + &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + while (mis->state == MIGRATION_STATUS_COLO) {
> + int request;
> +
> + colo_wait_handle_cmd(mis->from_src_file, &request, &local_err);
> + if (local_err) {
> + goto out;
> + }
> + assert(request);
> + /* FIXME: This is unnecessary for periodic checkpoint mode */
> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_CHECKPOINT_REPLY,
> + &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + colo_get_check_cmd(mis->from_src_file,
> + COLO_COMMAND_VMSTATE_SEND, &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + /* TODO: read migration data into colo buffer */
> +
> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_RECEIVED,
> + &local_err);
> + if (local_err) {
> + goto out;
> + }
> +
> + /* TODO: load vm state */
> +
> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_LOADED,
> + &local_err);
> + if (local_err) {
> + goto out;
> + }
> + }
>
> out:
> + /* Throw the unreported error message after exited from loop */
> + if (local_err) {
> + error_report_err(local_err);
> + }
> +
> if (mis->to_src_file) {
> qemu_fclose(mis->to_src_file);
> }
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 6eefad2..4ea4108 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -718,6 +718,31 @@
> { 'command': 'migrate-start-postcopy' }
>
> ##
> +# @COLOCommand
> +#
> +# The commands for COLO fault tolerance
> +#
> +# @checkpoint-ready: SVM is ready for checkpointing
> +#
> +# @checkpoint-request: PVM tells SVM to prepare for new checkpointing
> +#
> +# @checkpoint-reply: SVM gets PVM's checkpoint request
> +#
> +# @vmstate-send: VM's state will be sent by PVM.
> +#
> +# @vmstate-size: The total size of VMstate.
> +#
> +# @vmstate-received: VM's state has been received by SVM.
> +#
> +# @vmstate-loaded: VM's state has been loaded by SVM.
> +#
> +# Since: 2.6
> +##
> +{ 'enum': 'COLOCommand',
> + 'data': [ 'checkpoint-ready', 'checkpoint-request', 'checkpoint-reply',
> + 'vmstate-send', 'vmstate-size', 'vmstate-received',
> + 'vmstate-loaded' ] }
> +
> # @MouseInfo:
> #
> # Information about a mouse device.
> diff --git a/trace-events b/trace-events
> index 57ddc8f..51b2305 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1581,6 +1581,8 @@ postcopy_ram_incoming_cleanup_join(void) ""
>
> # migration/colo.c
> colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'"
> +colo_put_cmd(const char *msg) "Send '%s' cmd"
> +colo_get_cmd(const char *msg) "Receive '%s' cmd"
>
> # kvm-all.c
> kvm_ioctl(int type, void *arg) "type 0x%x, arg %p"
> --
> 1.8.3.1
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
