Re: [PATCH v3] x86/cpu: Add INTEL_LUNARLAKE_M to X86_BUG_MONITOR

From: Dave Hansen
Date: Wed Nov 20 2024 - 14:12:36 EST


On 11/12/24 18:07, Len Brown wrote:
> From: Len Brown <len.brown@xxxxxxxxx>
>
> 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.

This kinda implies that X86_BUG_MONITOR only does one thing. What about
the two other places in the tree that check it. Are those relevant?

> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219364
>
> Cc: stable@xxxxxxxxxxxxxxx # 6.11
> Signed-off-by: Len Brown <len.brown@xxxxxxxxx>

This obviously conflicts with the VFM infrastructure, but shouldn't this
also get backported to even older stable kernels?

I thought the "# 6.11" was to tell folks where it is *needed*, not where
it actually applies.