Virtualization - Aug 2013 - [PATCH] xen: initialize xen panic handler for PVHVM

kernel use callback linked in panic_notifier_list to notice others when panic
happens.
NORET_TYPE void panic(const char * fmt, ...){
    ...
    atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
}
When xen aware this, it will call xen_reboot(SHUTDOWN_crash) to send out an
event with reason code - SHUTDOWN_crash.
xen_panic_handler_init() is defined to register on panic_notifier_list but
we only call it in xen_arch_setup which only be called by pvm, this patch is
 necessary for pvhvm.

Signed-off-by: Vaughan Cao <vaughan.cao at oracle.com>
---
 arch/x86/xen/enlighten.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 4aec5ed..53e5726 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1713,6 +1713,8 @@ static void __init xen_hvm_guest_init(void)
 
 	xen_hvm_init_shared_info();
 
+	xen_panic_handler_init();
+
 	if (xen_feature(XENFEAT_hvm_callback_vector))
 		xen_have_vector_callback = 1;
 	xen_hvm_smp_init();
-- 
1.7.11.7

On Fri, Aug 16, 2013 at 04:10:56PM +0800, Vaughan Cao
wrote:
> kernel use callback linked in panic_notifier_list to notice others when
panic
> happens.
> NORET_TYPE void panic(const char * fmt, ...){
>     ...
>     atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
> }
> When xen aware this, it will call xen_reboot(SHUTDOWN_crash) to send out an
  ^^^^^^^^^^^^^^^^^^^-> "When Xen becomes aware of this"
> event with reason code - SHUTDOWN_crash.
> xen_panic_handler_init() is defined to register on panic_notifier_list but
> we only call it in xen_arch_setup which only be called by pvm, this patch
is
                                          ^^^^^^^-> "is
only"
>  necessary for pvhvm.
Could you tell me what has been happening without this patch?

Thank you.
> 
> Signed-off-by: Vaughan Cao <vaughan.cao at oracle.com>
> ---
>  arch/x86/xen/enlighten.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 4aec5ed..53e5726 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1713,6 +1713,8 @@ static void __init xen_hvm_guest_init(void)
>  
>  	xen_hvm_init_shared_info();
>  
> +	xen_panic_handler_init();
> +
>  	if (xen_feature(XENFEAT_hvm_callback_vector))
>  		xen_have_vector_callback = 1;
>  	xen_hvm_smp_init();
> -- 
> 1.7.11.7
>