Re: [PATCH] x86/APIC: Remove esr_disable

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Aug 29, 2023 at 04:46:21PM +0100, Andrew Cooper wrote:
> It is unconditionally 0 in Xen, and was deleted in Linux somewhere between 2.5
> and 2.6.
> 
> Remove it in Xen too.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> 
> I got bored waiting for `git log` to tell where it was disabled in Linux...
> ---
>  xen/arch/x86/apic.c                           | 50 ++++++-------------
>  .../x86/include/asm/mach-generic/mach_apic.h  |  3 --
>  2 files changed, 16 insertions(+), 37 deletions(-)
> 
> diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
> index 41879230ec90..5c6935ba42db 100644
> --- a/xen/arch/x86/apic.c
> +++ b/xen/arch/x86/apic.c
> @@ -496,14 +496,6 @@ void setup_local_APIC(bool bsp)
>      unsigned long oldvalue, value, maxlvt;
>      int i, j;
>  
> -    /* Pound the ESR really hard over the head with a big hammer - mbligh */
> -    if (esr_disable) {
> -        apic_write(APIC_ESR, 0);
> -        apic_write(APIC_ESR, 0);
> -        apic_write(APIC_ESR, 0);
> -        apic_write(APIC_ESR, 0);
> -    }
> -
>      BUILD_BUG_ON((SPURIOUS_APIC_VECTOR & 0x0f) != 0x0f);
>  
>      /*
> @@ -628,33 +620,23 @@ void setup_local_APIC(bool bsp)
>          value = APIC_DM_NMI | APIC_LVT_MASKED;
>      apic_write(APIC_LVT1, value);
>  
> -    if (!esr_disable) {
> -        maxlvt = get_maxlvt();
> -        if (maxlvt > 3)     /* Due to the Pentium erratum 3AP. */
> -            apic_write(APIC_ESR, 0);
> -        oldvalue = apic_read(APIC_ESR);
> +    maxlvt = get_maxlvt();
> +    if (maxlvt > 3)     /* Due to the Pentium erratum 3AP. */
> +        apic_write(APIC_ESR, 0);
> +    oldvalue = apic_read(APIC_ESR);
>  
> -        value = ERROR_APIC_VECTOR;      // enables sending errors
> -        apic_write(APIC_LVTERR, value);
> -        /*
> -         * spec says clear errors after enabling vector.
> -         */
> -        if (maxlvt > 3)
> -            apic_write(APIC_ESR, 0);
> -        value = apic_read(APIC_ESR);
> -        if (value != oldvalue)
> -            apic_printk(APIC_VERBOSE, "ESR value before enabling "
> -                        "vector: %#lx  after: %#lx\n",
> -                        oldvalue, value);
> -    } else {
> -        /*
> -         * Something untraceble is creating bad interrupts on
> -         * secondary quads ... for the moment, just leave the
> -         * ESR disabled - we can't do anything useful with the
> -         * errors anyway - mbligh
> -         */
> -        printk("Leaving ESR disabled.\n");
> -    }
> +    value = ERROR_APIC_VECTOR;      // enables sending errors
> +    apic_write(APIC_LVTERR, value);
> +    /*
> +     * spec says clear errors after enabling vector.

Is it worth making this a one-line comment while adjusting padding?

Regardless:

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, Roger.