linux-kernel - Re: [PATCH v3] x86/cpu: Add INTEL_LUNARLAKE_M to X86_BUG

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Message-ID: <CAJZ5v0h5TfKkdbvhnPoM9fmBOMr+gCOzy-_zNdCGX=McF+Awqg@mail.gmail.com>
Date: Wed, 13 Nov 2024 10:05:01 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Len Brown <lenb@...nel.org>
Cc: peterz@...radead.org, tglx@...utronix.de, x86@...nel.org, 
	rafael@...nel.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, 
	Len Brown <len.brown@...el.com>, stable@...r.kernel.org
Subject: Re: [PATCH v3] x86/cpu: Add INTEL_LUNARLAKE_M to X86_BUG_MONITOR

On Wed, Nov 13, 2024 at 3:07 AM Len Brown <lenb@...nel.org> wrote:
>
> From: Len Brown <len.brown@...el.com>
>
> Under some conditions, MONITOR wakeups on Lunar Lake processors
> can be lost, resulting in significant user-visible delays.
>
> Add LunarLake to X86_BUG_MONITOR so that wake_up_idle_cpu()
> always sends an IPI, avoiding this potential delay.
>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219364
>
> Cc: stable@...r.kernel.org # 6.11
> Signed-off-by: Len Brown <len.brown@...el.com>

Still

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
> v3 syntax tweak
> v2 leave smp_kick_mwait_play_dead() alone
>
>  arch/x86/kernel/cpu/intel.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index e7656cbef68d..4b5f3d052151 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -586,7 +586,9 @@ static void init_intel(struct cpuinfo_x86 *c)
>              c->x86_vfm == INTEL_WESTMERE_EX))
>                 set_cpu_bug(c, X86_BUG_CLFLUSH_MONITOR);
>
> -       if (boot_cpu_has(X86_FEATURE_MWAIT) && c->x86_vfm == INTEL_ATOM_GOLDMONT)
> +       if (boot_cpu_has(X86_FEATURE_MWAIT) &&
> +           (c->x86_vfm == INTEL_ATOM_GOLDMONT ||
> +            c->x86_vfm == INTEL_LUNARLAKE_M))
>                 set_cpu_bug(c, X86_BUG_MONITOR);
>
>  #ifdef CONFIG_X86_64
> --
> 2.43.0
>