linux-kernel - Re: [PATCH v2] x86/xen: Return from panic notifier

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Message-ID: <9995b9f1-3d58-7caa-9ce6-13475445d4ac@suse.com>
Date:   Fri, 4 Oct 2019 06:37:48 +0200
From:   Jürgen Groß <jgross@...e.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     james@...gwall.me.uk, Jan Beulich <jbeulich@...e.com>
Subject: Re: [PATCH v2] x86/xen: Return from panic notifier

On 03.10.19 20:12, Boris Ostrovsky wrote:
> Currently execution of panic() continues until Xen's panic notifier
> (xen_panic_event()) is called at which point we make a hypercall that
> never returns.
> 
> This means that any notifier that is supposed to be called later as
> well as significant part of panic() code (such as pstore writes from
> kmsg_dump()) is never executed.
> 
> There is no reason for xen_panic_event() to be this last point in
> execution since panic()'s emergency_restart() will call into
> xen_emergency_restart() from where we can perform our hypercall.
> 
> Nevertheless, we will provide xen_legacy_crash boot option that will
> preserve original behavior during crash. This option could be used,
> for example, if running kernel dumper (which happens after panic
> notifiers) is undesirable.
> 
> Reported-by: James Dingwall <james@...gwall.me.uk>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen