linux-kernel - RE: [EXTERNAL] Re: [PATCH hyperv-next v3] arch/x86: Provide the CPU number in the wakeup AP callback

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Message-ID:
 <KUZP153MB1444BF0D51C59D3E24A61B13BE88A@KUZP153MB1444.APCP153.PROD.OUTLOOK.COM>
Date: Wed, 7 May 2025 06:22:24 +0000
From: Saurabh Singh Sengar <ssengar@...rosoft.com>
To: Wei Liu <wei.liu@...nel.org>, Roman Kisel <romank@...ux.microsoft.com>
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Subject: RE: [EXTERNAL] Re: [PATCH hyperv-next v3] arch/x86: Provide the CPU
 number in the wakeup AP callback

> On Wed, Apr 30, 2025 at 01:47:20PM -0700, Roman Kisel 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>
> 
> Queued to hyperv-next. Thanks.

We need to update numachip_wakeup_secondary as well, otherwise this will break the builds.

Regards,
Saurabh