linux-kernel - Re: [PATCH 1/1] Drivers: hv: vmbus: Only notify Hyper-V for die events that are oops

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Date:   Fri, 7 Aug 2020 13:49:30 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     Michael Kelley <mikelley@...rosoft.com>,
        linux-kernel@...r.kernel.org, kys@...rosoft.com,
        sthemmin@...rosoft.com, wei.liu@...nel.org,
        linux-hyperv@...r.kernel.org
Subject: Re: [PATCH 1/1] Drivers: hv: vmbus: Only notify Hyper-V for die
 events that are oops

On Fri, Aug 07, 2020 at 11:06:47AM +0200, Vitaly Kuznetsov wrote:
> Michael Kelley <mikelley@...rosoft.com> writes:
> 
> > Hyper-V currently may be notified of a panic for any die event. But
> > this results in false panic notifications for various user space traps
> > that are die events. Fix this by ignoring die events that aren't oops.
> >
> > Fixes: 510f7aef65bb ("Drivers: hv: vmbus: prefer 'die' notification chain to 'panic'")
> > Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
> > ---
> >  drivers/hv/vmbus_drv.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index b50081c..910b6e9 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -86,6 +86,10 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
> >  	struct die_args *die = (struct die_args *)args;
> >  	struct pt_regs *regs = die->regs;
> >  
> > +	/* Don't notify Hyper-V if the die event is other than oops */
> > +	if (val != DIE_OOPS)
> > +		return NOTIFY_DONE;
> > +
> 
> Looking at die_val enum, DIE_PANIC also sounds like something we would
> want to report but it doesn't get emitted anywhere and honestly I don't
> quite understand how is was supposed to be different from DIE_OOPS.
> 
> Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

Applied to hyperv-fixes.

Wei.

> 
> >  	/*
> >  	 * Hyper-V should be notified only once about a panic.  If we will be
> >  	 * doing hyperv_report_panic_msg() later with kmsg data, don't do
> 
> -- 
> Vitaly
>