linux-kernel - Re: [PATCH 4/7] x86/kexec: Disable kexec/kdump on platforms with TDX partial write erratum

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Message-ID: <CAGtprH__G96uUmiDkK0iYM2miXb31vYje9aN+J=stJQqLUUXEg@mail.gmail.com>
Date: Mon, 29 Sep 2025 18:38:38 -0700
From: Vishal Annapurve <vannapurve@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, dave.hansen@...el.com, 
	bp@...en8.de, tglx@...utronix.de, peterz@...radead.org, mingo@...hat.com, 
	hpa@...or.com, thomas.lendacky@....com, x86@...nel.org, kas@...nel.org, 
	rick.p.edgecombe@...el.com, dwmw@...zon.co.uk, kai.huang@...el.com, 
	seanjc@...gle.com, reinette.chatre@...el.com, isaku.yamahata@...el.com, 
	dan.j.williams@...el.com, ashish.kalra@....com, nik.borisov@...e.com, 
	chao.gao@...el.com, sagis@...gle.com, farrah.chen@...el.com, 
	Binbin Wu <binbin.wu@...ux.intel.com>
Subject: Re: [PATCH 4/7] x86/kexec: Disable kexec/kdump on platforms with TDX
 partial write erratum

On Mon, Sep 1, 2025 at 9:11 AM Paolo Bonzini <pbonzini@...hat.com> wrote:
>
> From: Kai Huang <kai.huang@...el.com>
>
> Some early TDX-capable platforms have an erratum: A kernel partial
> write (a write transaction of less than cacheline lands at memory
> controller) to TDX private memory poisons that memory, and a subsequent
> read triggers a machine check.
>
> On those platforms, the old kernel must reset TDX private memory before
> jumping to the new kernel, otherwise the new kernel may see unexpected
> machine check.  Currently the kernel doesn't track which page is a TDX
> private page.  For simplicity just fail kexec/kdump for those platforms.

Google has a usecase that needs host kdump support on SPR/EMR
platforms. Disabling kdump disables the host's ability to dump very
critical information on host crashes altogether. Is Intel working on
enabling kdump support for platforms with the erratum?