[libvirt] [PATCH V2 3/3] libxl: add support for soft reset

[Michal Privoznik]

On 10/31/2018 08:51 PM, Jim Fehlig wrote:
> The pvops Linux kernel implements machine_ops.crash_shutdown as
> 
> static void xen_hvm_crash_shutdown(struct pt_regs *regs)
> {
>         native_machine_crash_shutdown(regs);
>         xen_reboot(SHUTDOWN_soft_reset);
> }
> 
> but currently the libxl driver does not handle the soft reset
> shutdown event. As a result, the guest domain never proceeds
> past xen_reboot(), making it impossible for HVM domains to save
> a crash dump using kexec.
> 
> This patch adds support for handling the soft reset event by
> calling libxl_domain_soft_reset() and re-enabling domain death
> events, which is similar to the xl tool handling of soft reset
> shutdown event.
> 
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
> 
> V2: Check for availability of soft reset with LIBXL_HAVE_SOFT_RESET
> 
>  src/libxl/libxl_domain.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
> index 4cdaee0e51..47c1f49538 100644
> --- a/src/libxl/libxl_domain.c
> +++ b/src/libxl/libxl_domain.c
> @@ -471,8 +471,10 @@ libxlDomainShutdownThread(void *opaque)
>      virObjectEventPtr dom_event = NULL;
>      libxl_shutdown_reason xl_reason = ev->u.domain_shutdown.shutdown_reason;
>      libxlDriverConfigPtr cfg;
> +    libxl_domain_config d_config;
>  
>      cfg = libxlDriverConfigGet(driver);
> +    libxl_domain_config_init(&d_config);
>  
>      vm = virDomainObjListFindByID(driver->domains, ev->domid);
>      if (!vm) {
> @@ -563,6 +565,33 @@ libxlDomainShutdownThread(void *opaque)
>           * Similar to the xl implementation, ignore SUSPEND.  Any actions needed
>           * after calling libxl_domain_suspend() are handled by it's callers.
>           */
> +#ifdef LIBXL_HAVE_SOFT_RESET
> +    } else if (xl_reason == LIBXL_SHUTDOWN_REASON_SOFT_RESET) {
> +        libxlDomainObjPrivatePtr priv = vm->privateData;

I'd put an empty line here.

> +        if (libxl_retrieve_domain_configuration(cfg->ctx, vm->def->id,
> +                                                &d_config) != 0) {
> +            VIR_ERROR(_("Failed to retrieve config for VM '%s'. "
> +                        "Unable to perform soft reset. Destroying VM"),
> +                      vm->def->name);
> +            libxlDomainShutdownHandleDestroy(driver, vm);
> +            goto endjob;
> +        }
> +
> +        if (priv->deathW) {
> +            libxl_evdisable_domain_death(cfg->ctx, priv->deathW);
> +            priv->deathW = NULL;
> +        }
> +
> +        if (libxl_domain_soft_reset(cfg->ctx, &d_config, vm->def->id,
> +                                    NULL, NULL) != 0) {
> +            VIR_ERROR(_("Failed to soft reset VM '%s'. Destroying VM"),
> +                      vm->def->name);
> +            libxlDomainShutdownHandleDestroy(driver, vm);
> +            goto endjob;
> +        }
> +        libxl_evenable_domain_death(cfg->ctx, vm->def->id, 0, &priv->deathW);
> +        libxl_domain_unpause(cfg->ctx, vm->def->id);
> +#endif
>      } else {
>          VIR_INFO("Unhandled shutdown_reason %d", xl_reason);
>      }
> 

Michal