ACK/CMNT: [SRU][FOCAL/linux-azure][BIONIC/linux-azure-4.15][PATCH 1/1] Drivers: hv: vmbus: Only notify Hyper-V for die events that are oops

[Thadeu Lima de Souza Cascardo]

On Tue, Aug 18, 2020 at 02:43:03PM -0400, William Breathitt Gray wrote:
> From: Michael Kelley <mikelley at microsoft.com>
> 
> 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 at microsoft.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets at redhat.com>
> Link: https://lore.kernel.org/r/1596730935-11564-1-git-send-email-mikelley@microsoft.com
> Signed-off-by: Wei Liu <wei.liu at kernel.org>
> 
> BugLink: https://bugs.launchpad.net/bugs/1891222

So, assuming this will be tested by Microsoft, but please have them document
the test case (what to look for on a Hyper-V UI), and what are the risks of
missing events here or what else could be broken by this. So, basically, please
get the SRU template filled up in the bug.

Acked-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>

> 
> (cherry picked from commit 608a973bd52ef1705941b18f55e39655fcfe9cdb)
> Signed-off-by: William Breathitt Gray <william.gray at canonical.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 0f168f0b1a8f..c97f1964d9ed 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -97,6 +97,10 @@ 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;
> +
>  	/*
>  	 * 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
> -- 
> 2.25.1
> 
> 
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