[libvirt] [PATCH] libxl: add support for soft reset

[Jim Fehlig]

On 10/29/18 7:26 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>
> ---
>   src/libxl/libxl_domain.c | 30 ++++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
> 
> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
> index 0032b9dd11..295ec04a85 100644
> --- a/src/libxl/libxl_domain.c
> +++ b/src/libxl/libxl_domain.c
> @@ -447,8 +447,10 @@ 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) {
> @@ -532,6 +534,33 @@ libxlDomainShutdownThread(void *opaque)
>            * after calling libxl_domain_suspend() are handled by it's callers.
>            */
>           goto endjob;
> +    } else if (xl_reason == LIBXL_SHUTDOWN_REASON_SOFT_RESET) {
> +        libxlDomainObjPrivatePtr priv = vm->privateData;
> +        int res;

I'm not sure why I have this useless local. I've squashed the below diff into my 
local branch.

Regards,
Jim

diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
index 295ec04a85..af5127bc2f 100644
--- a/src/libxl/libxl_domain.c
+++ b/src/libxl/libxl_domain.c
@@ -536,7 +536,6 @@ libxlDomainShutdownThread(void *opaque)
          goto endjob;
      } else if (xl_reason == LIBXL_SHUTDOWN_REASON_SOFT_RESET) {
          libxlDomainObjPrivatePtr priv = vm->privateData;
-        int res;

          if (libxl_retrieve_domain_configuration(cfg->ctx, vm->def->id,
                                                  &d_config) != 0) {
@@ -551,9 +550,8 @@ libxlDomainShutdownThread(void *opaque)
              priv->deathW = NULL;
          }

-        res = libxl_domain_soft_reset(cfg->ctx, &d_config, vm->def->id,
-                                      NULL, NULL);
-        if (res != 0) {
+        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);
              goto destroy;