linux-kernel - Re: [PATCH v2 2/6] x86/irq: Extend NMI handler registration interface to include source

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Date: Mon, 24 Jun 2024 16:16:52 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: Jacob Pan <jacob.jun.pan@...ux.intel.com>, X86 Kernel <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Dave Hansen <dave.hansen@...el.com>, "H. Peter Anvin" <hpa@...or.com>, "Ingo
 Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	<linux-perf-users@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>
CC: Andi Kleen <andi.kleen@...el.com>, Xin Li <xin3.li@...el.com>
Subject: Re: [PATCH v2 2/6] x86/irq: Extend NMI handler registration interface
 to include source

On 6/11/2024 9:54 AM, Jacob Pan wrote:
> Add a source vector argument to register_nmi_handler() such that designated
> NMI originators can leverage NMI source reporting feature. For those who
> do not use NMI source reporting, 0 (unknown) is used as the source vector. NMI
> source vectors (up to 16) are pre-defined.
> 

What determines whether a source supports the new reporting vs some that
don't? It might be useful to add that reasoning to the commit message as
well.

I am guessing there is some connection to NMI_LOCAL based on
use_nmi_source() definition but I am not sure.

Also, would it be worthwhile to split this patch into 2? One part that
extents the register_nmi_handler() API and another that allocates the
source vectors to certain sources.


> +static inline bool use_nmi_source(unsigned int type, struct nmiaction *a)
> +{
> +	return (cpu_feature_enabled(X86_FEATURE_NMI_SOURCE) &&
> +		type == NMI_LOCAL && a->source_vec);
> +}
> +

Sohil