linux-kernel - Re: [PATCH] x86: Disable kexec for TDX guests

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Message-ID: <dfd8466a-9693-e469-31be-3d9158f19263@intel.com>
Date:   Sat, 25 Mar 2023 09:20:47 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Eric Biederman <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Disable kexec for TDX guests

On 3/25/23 09:01, Kirill A. Shutemov wrote:
> The last item is tricky. TDX guests use ACPI MADT MPWK to bring up
> secondary CPUs. The mechanism doesn't allow to put a CPU back offline if
> it has woken up.

I'm not sure I like this approach.

TDX uses the MADT exclusively.

MADT-based systems can't offline CPUs.

kexec() requires