linux-kernel - Re: [PATCH v3 2/2] x86/sev: Add support to unaccept memory after hot-remove

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Message-ID: <9e29a8f6-9fbb-4599-93b5-55235192ffca@amd.com>
Date: Thu, 29 Jan 2026 13:32:05 -0600
From: "Pratik R. Sampat" <prsampat@....com>
To: Dave Hansen <dave.hansen@...el.com>, Kiryl Shutsemau <kas@...nel.org>
Cc: linux-mm@...ck.org, linux-coco@...ts.linux.dev, x86@...nel.org,
 linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
 bp@...en8.de, dave.hansen@...ux.intel.com, ardb@...nel.org,
 akpm@...ux-foundation.org, david@...nel.org, osalvador@...e.de,
 thomas.lendacky@....com, michael.roth@....com
Subject: Re: [PATCH v3 2/2] x86/sev: Add support to unaccept memory after
 hot-remove

On 1/29/26 11:39 AM, Dave Hansen wrote:
> On 1/29/26 09:32, Pratik R. Sampat wrote:
>> In that case a fall through for TDX (with a comment explaining why) and
>> panic for rest may be the way to go?
> 
> No. panic() is an absolute last resort. It's almost never the way to go.
> 
> What else can we do to ensure we never reach this code if the platform
> doesn't support memory un-acceptance?

The panic() here similar to its existing arch_accept_memory() counterpart is
mostly to guard against a cant-happen scenario (unless Kiryl had a different
intention writing the initial hook). It is called from functions that compile
this in only if CONFIG_UNACCEPTED_MEMORY is enabled. TDX and SNP are the only
two users of it today.