linux-kernel - Re: [PATCH] misc: pvpanic: add crash loaded event

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Date:   Thu, 12 Dec 2019 14:01:55 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     zhenwei pi <pizhenwei@...edance.com>
Cc:     arnd@...db.de, peng.hao2@....com.cn, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] misc: pvpanic: add crash loaded event

On Thu, Dec 12, 2019 at 08:32:26PM +0800, zhenwei pi wrote:
> Some users prefer kdump tools to generate guest kernel dumpfile,
> at the same time, need a out-of-band kernel panic event.
> 
> Currently if booting guest kernel with 'crash_kexec_post_notifiers',
> QEMU will recieve PVPANIC_PANICKED event and stop VM. If booting
> guest kernel without 'crash_kexec_post_notifiers', guest will not
> call notifier chain.
> 
> Add PVPANIC_CRASH_LOADED bit for pvpanic event, it means that guest
> actually hit a kernel panic, but kernel wants to handle by itself.
> 
> Signed-off-by: zhenwei pi <pizhenwei@...edance.com>
> ---
>  drivers/misc/pvpanic.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/pvpanic.c b/drivers/misc/pvpanic.c
> index 95ff7c5a1dfb..a8cc96c90550 100644
> --- a/drivers/misc/pvpanic.c
> +++ b/drivers/misc/pvpanic.c
> @@ -10,6 +10,7 @@
>  
>  #include <linux/acpi.h>
>  #include <linux/kernel.h>
> +#include <linux/kexec.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_address.h>
> @@ -19,6 +20,7 @@
>  static void __iomem *base;
>  
>  #define PVPANIC_PANICKED        (1 << 0)
> +#define PVPANIC_CRASH_LOADED    (1 << 1)

BIT(1)?

>  MODULE_AUTHOR("Hu Tao <hutao@...fujitsu.com>");
>  MODULE_DESCRIPTION("pvpanic device driver");
> @@ -34,7 +36,13 @@ static int
>  pvpanic_panic_notify(struct notifier_block *nb, unsigned long code,
>  		     void *unused)
>  {
> -	pvpanic_send_event(PVPANIC_PANICKED);
> +	unsigned int event = PVPANIC_PANICKED;
> +
> +	if (kexec_crash_loaded())
> +		event = PVPANIC_CRASH_LOADED;
> +
> +	pvpanic_send_event(event);

Who gets this event to know that the above new bit is set or not?

thanks,

greg k-h