linux-kernel - Re: [PATCH hyperv-next 2/2] arch/x86: Provide the CPU number in the wakeup AP callback

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Message-ID: <aBwEnI9BRJHGzlzG@liuwe-devbox-ubuntu-v2.tail21d00.ts.net>
Date: Thu, 8 May 2025 01:10:52 +0000
From: Wei Liu <wei.liu@...nel.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Roman Kisel <romank@...ux.microsoft.com>, ardb@...nel.org, bp@...en8.de,
	brgerst@...il.com, dave.hansen@...ux.intel.com, decui@...rosoft.com,
	dimitri.sivanich@....com, gautham.shenoy@....com,
	haiyangz@...rosoft.com, hpa@...or.com, imran.f.khan@...cle.com,
	jacob.jun.pan@...ux.intel.com, jpoimboe@...nel.org,
	justin.ernst@....com, kprateek.nayak@....com, kyle.meyer@....com,
	kys@...rosoft.com, lenb@...nel.org, mhklinux@...look.com,
	mingo@...hat.com, nikunj@....com, papaluri@....com,
	patryk.wlazlyn@...ux.intel.com, peterz@...radead.org,
	russ.anderson@....com, sohil.mehta@...el.com, steve.wahl@....com,
	tglx@...utronix.de, thomas.lendacky@....com, tiala@...rosoft.com,
	wei.liu@...nel.org, yuehaibing@...wei.com,
	linux-acpi@...r.kernel.org, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org, apais@...rosoft.com,
	benhill@...rosoft.com, bperkins@...rosoft.com,
	sunilmut@...rosoft.com
Subject: Re: [PATCH hyperv-next 2/2] arch/x86: Provide the CPU number in the
 wakeup AP callback

On Wed, May 07, 2025 at 10:09:46PM +0200, Rafael J. Wysocki wrote:
> On Wed, May 7, 2025 at 8:22 PM Roman Kisel <romank@...ux.microsoft.com> wrote:
> >
> > When starting APs, confidential guests and paravisor guests
> > need to know the CPU number, and the pattern of using the linear
> > search has emerged in several places. With N processors that leads
> > to the O(N^2) time complexity.
> >
> > Provide the CPU number in the AP wake up callback so that one can
> > get the CPU number in constant time.
> >
> > Suggested-by: Michael Kelley <mhklinux@...look.com>
> > Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
> > Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
> > Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
> > Reviewed-by: Michael Kelley <mhklinux@...look.com>
> 
> For the ACPI bits
> 
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> and I'm assuming that the x86 folks will take care of this.
> 

Thank you Rafael. I will take this patch via the hyperv-next tree.