linux-kernel - Re: [PATCHv6 00/16] x86/tdx: Add kexec support

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Date: Wed, 31 Jan 2024 09:31:21 +0200
From: Nikolay Borisov <nik.borisov@...e.com>
To: Paolo Bonzini <pbonzini@...hat.com>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Thomas Gleixner <tglx@...utronix.de>, 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
Subject: Re: [PATCHv6 00/16] x86/tdx: Add kexec support

On 30.01.24 г. 15:43 ч., Paolo Bonzini wrote:
> On 1/24/24 13:55, Kirill A. Shutemov wrote:
>> The patchset adds bits and pieces to get kexec (and crashkernel) work on
>> TDX guest.
>>
>> The last patch implements CPU offlining according to the approved ACPI
>> spec change poposal[1]. It unlocks kexec with all CPUs visible in the 
>> target
>> kernel. It requires BIOS-side enabling. If it missing we fallback to 
>> booting
>> 2nd kernel with single CPU.
>>
>> Please review. I would be glad for any feedback.
> 
> Hi Kirill,
> 
> I have a very basic question: is there a reason why this series does not 
> revert commit cb8eb06d50fc, "x86/virt/tdx: Disable TDX host support when 
> kexec is enabled"?

While on the topic, Paolo do you think it's  better to have a runtime 
disable of kexec rather than at compile time:

[RFC PATCH] x86/virt/tdx: Disable KEXEC in the presence of TDX

20240118160118.1899299-1-nik.borisov@...e.com

I'm trying to get traction for this patch.

> 
> Thanks,
> 
> Paolo
> 
>