linux-kernel - Re: [PATCH 6/6] x86/irq: remove unused vectors from <asm/irq

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Date:   Tue, 11 May 2021 12:04:12 -0500
From:   Steve Wahl <steve.wahl@....com>
To:     "H. Peter Anvin" <hpa@...or.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Steve Wahl <steve.wahl@....com>,
        Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Russ Anderson <russ.anderson@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/6] x86/irq: remove unused vectors from
 <asm/irq_vectors.h>

Acked-by: Steve Wahl <steve.wahl@....com>

Yes, we believe UV_BAU_MESSAGE is one we missed in some earlier code
cleanup, and agree with its removal.

On Mon, May 10, 2021 at 05:55:31PM -0700, H. Peter Anvin wrote:
> From: "H. Peter Anvin (Intel)" <hpa@...or.com>
> 
> UV_BAU_MESSAGE is defined but not used anywhere in the
> kernel. Presumably this is a stale vector number that can be
> reclaimed.
> 
> MCE_VECTOR is not an actual vector: #MC is an exception, not an
> interrupt vector, and as such is correctly described as
> X86_TRAP_MC. MCE_VECTOR is not used anywhere is the kernel.
> 
> Note that NMI_VECTOR *is* used; specifically it is the vector number
> programmed into the APIC LVT when an NMI interrupt is configured. At
> the moment it is always numerically identical to X86_TRAP_NMI, that is
> not necessarily going to be the case indefinitely.
> 
> Cc: Steve Wahl <steve.wahl@....com>
> Cc: Mike Travis <mike.travis@....com>
> Cc: Dimitri Sivanich <dimitri.sivanich@....com>
> Cc: Russ Anderson <russ.anderson@....com>
> Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
> ---
>  arch/x86/include/asm/irq_vectors.h       | 4 ++--
>  tools/arch/x86/include/asm/irq_vectors.h | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
> index d2ef35927770..43dcb9284208 100644
> --- a/arch/x86/include/asm/irq_vectors.h
> +++ b/arch/x86/include/asm/irq_vectors.h
> @@ -26,8 +26,8 @@
>   * This file enumerates the exact layout of them:
>   */
>  
> +/* This is used as an interrupt vector when programming the APIC. */
>  #define NMI_VECTOR			0x02
> -#define MCE_VECTOR			0x12
>  
>  /*
>   * IDT vectors usable for external interrupt sources start at 0x20.
> @@ -84,7 +84,7 @@
>   */
>  #define IRQ_WORK_VECTOR			0xf6
>  
> -#define UV_BAU_MESSAGE			0xf5
> +/* 0xf5 - unused, was UV_BAU_MESSAGE */
>  #define DEFERRED_ERROR_VECTOR		0xf4
>  
>  /* Vector on which hypervisor callbacks will be delivered */
> diff --git a/tools/arch/x86/include/asm/irq_vectors.h b/tools/arch/x86/include/asm/irq_vectors.h
> index d2ef35927770..43dcb9284208 100644
> --- a/tools/arch/x86/include/asm/irq_vectors.h
> +++ b/tools/arch/x86/include/asm/irq_vectors.h
> @@ -26,8 +26,8 @@
>   * This file enumerates the exact layout of them:
>   */
>  
> +/* This is used as an interrupt vector when programming the APIC. */
>  #define NMI_VECTOR			0x02
> -#define MCE_VECTOR			0x12
>  
>  /*
>   * IDT vectors usable for external interrupt sources start at 0x20.
> @@ -84,7 +84,7 @@
>   */
>  #define IRQ_WORK_VECTOR			0xf6
>  
> -#define UV_BAU_MESSAGE			0xf5
> +/* 0xf5 - unused, was UV_BAU_MESSAGE */
>  #define DEFERRED_ERROR_VECTOR		0xf4
>  
>  /* Vector on which hypervisor callbacks will be delivered */
> -- 
> 2.31.1
> 

-- 
Steve Wahl, Hewlett Packard Enterprise