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

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Message-ID: <74a390a1-42a7-4e6b-a76a-f88f49323c93@intel.com>
Date: Tue, 30 Sep 2025 14:32:35 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Vishal Annapurve <vannapurve@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 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 9/29/25 18:38, Vishal Annapurve wrote:
>> 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?

Nope.

Any workarounds are going to be slow and probably imperfect. That's not
a great match for kdump. I'm perfectly happy waiting for fixed hardware
from what I've seen.