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

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Message-ID: <3b0c3732-ccf6-4133-b55c-4177532ebecb@linux.microsoft.com>
Date: Wed, 7 May 2025 10:07:27 -0700
From: Roman Kisel <romank@...ux.microsoft.com>
To: Wei Liu <wei.liu@...nel.org>
Cc: ardb@...nel.org, bp@...en8.de, dave.hansen@...ux.intel.com,
 decui@...rosoft.com, dimitri.sivanich@....com, haiyangz@...rosoft.com,
 hpa@...or.com, imran.f.khan@...cle.com, jacob.jun.pan@...ux.intel.com,
 jgross@...e.com, justin.ernst@....com, kprateek.nayak@....com,
 kyle.meyer@....com, kys@...rosoft.com, lenb@...nel.org, mingo@...hat.com,
 nikunj@....com, papaluri@....com, perry.yuan@....com, peterz@...radead.org,
 rafael@...nel.org, russ.anderson@....com, steve.wahl@....com,
 tglx@...utronix.de, thomas.lendacky@....com, tim.c.chen@...ux.intel.com,
 tony.luck@...el.com, xin@...or.com, 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 v3] arch/x86: Provide the CPU number in the
 wakeup AP callback



On 5/6/2025 11:23 PM, Wei Liu wrote:
> On Tue, May 06, 2025 at 02:58:34AM +0000, Wei Liu wrote:
>> 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.
> 
> This patch broke linux-next. I have dropped it. Please change
> numachip_wakeup_secondary.
> 

Thanks for your help! Working on that.

> Wei.

-- 
Thank you,
Roman