Re: [Xen-devel] [PATCH v4 8/9] libxl: soft reset support

[Wei Liu <wei.liu2@xxxxxxxxxx>]

(I've skipped the internal implementation since I don't know what's
 required to fulfil soft reset.)

On Wed, Dec 03, 2014 at 06:16:20PM +0100, Vitaly Kuznetsov wrote:
[...]
> +                                         libxl__domain_create_state *dcs);
>  
>  /* Each time the dm needs to be saved, we must call suspend and then save */
>  _hidden int libxl__domain_suspend_device_model(libxl__gc *gc,
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index 53611dc..eb833f0 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -2043,7 +2043,8 @@ static void reload_domain_config(uint32_t domid,
>  }
>  
>  /* Returns 1 if domain should be restarted,
> - * 2 if domain should be renamed then restarted, or 0
> + * 2 if domain should be renamed then restarted,
> + * 3 if domain performed soft reset, or 0
>   * Can update r_domid if domain is destroyed etc */
>  static int handle_domain_death(uint32_t *r_domid,
>                                 libxl_event *event,
> @@ -2069,6 +2070,9 @@ static int handle_domain_death(uint32_t *r_domid,
>      case LIBXL_SHUTDOWN_REASON_WATCHDOG:
>          action = d_config->on_watchdog;
>          break;
> +    case LIBXL_SHUTDOWN_REASON_SOFT_RESET:
> +        LOG("Domain performed soft reset.");
> +        return 3;

Would it be useful to provide "on_soft_reset" option in xl? Will the
admin be interested in performing some other action when domain does
soft reset? Say, for security reason admin want to prohibit domain from
soft resetting itself.

>      default:
>          LOG("Unknown shutdown reason code %d. Destroying domain.",
>              event->u.domain_shutdown.shutdown_reason);
> @@ -2285,6 +2289,7 @@ static void 
> evdisable_disk_ejects(libxl_evgen_disk_eject **diskws,
>  static uint32_t create_domain(struct domain_create *dom_info)
>  {
>      uint32_t domid = INVALID_DOMID;
> +    uint32_t domid_old = INVALID_DOMID;
>  
>      libxl_domain_config d_config;
>  
> @@ -2510,7 +2515,18 @@ start:
>           * restore/migrate-receive it again.
>           */
>          restoring = 0;
> -    }else{
> +    } else if (domid_old != INVALID_DOMID) {
> +        /* Do soft reset */
> +        d_config.b_info.nodemap.size = 0;

What's the reason for doing this?

If you encounter problem with this it should probably be fixed in libxl.

Wei.

> +        ret = libxl_domain_soft_reset(ctx, &d_config,
> +                                      &domid, domid_old,
> +                                      0, 0);
> +
> +        if ( ret ) {
> +            goto error_out;
> +        }
> +        domid_old = INVALID_DOMID;
> +    } else {
>          ret = libxl_domain_create_new(ctx, &d_config, &domid,
>                                        0, autoconnect_console_how);
>      }
> @@ -2574,6 +2590,8 @@ start:
>                  event->u.domain_shutdown.shutdown_reason,
>                  event->u.domain_shutdown.shutdown_reason);
>              switch (handle_domain_death(&domid, event, &d_config)) {
> +            case 3:
> +                domid_old = domid;
>              case 2:
>                  if (!preserve_domain(&domid, event, &d_config)) {
>                      /* If we fail then exit leaving the old domain in place. 
> */
> -- 
> 1.9.3
> 
> 
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