linux-kernel - Re: [PATCHv2 02/13] kernel/cpu: Add support for declaring CPU offlining not supported

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Date:   Sat, 28 Oct 2023 16:12:10 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        "Kalra, Ashish" <ashish.kalra@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        "Huang, Kai" <kai.huang@...el.com>, Baoquan He <bhe@...hat.com>,
        kexec@...ts.infradead.org, linux-coco@...ts.linux.dev,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv2 02/13] kernel/cpu: Add support for declaring CPU
 offlining not supported

On Fri, Oct 20 2023 at 18:12, Kirill A. Shutemov wrote:

Subject: cpu/hotplug: ...

> ACPI MADT doesn't allow to offline CPU after it got woke up.

ACPI MADT is a table ...

This is about the MADT mailbox wakeup method, right?

> Currently offlining hotplug prevented based on the confidential

is prevented

> computing attribute which is set for Intel TDX. But TDX is not
> the only possible user of the wake up method.
>
> Introduce cpu_hotplug_not_supported() that can be called to indicate
> that CPU offlining should be disabled.

Otherwise the changes look good!