linux-kernel - Re: [PATCH 0/3] Resolve problems with kexec identity mapping

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Date: Mon, 1 Jul 2024 16:27:04 +0200
From: Borislav Petkov <bp@...en8.de>
To: Steve Wahl <steve.wahl@....com>
Cc: Ashish Kalra <ashish.kalra@....com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Pavin Joseph <me@...injoseph.com>,
	Eric Hagberg <ehagberg@...il.com>,
	Simon Horman <horms@...ge.net.au>,
	Eric Biederman <ebiederm@...ssion.com>,
	Dave Young <dyoung@...hat.com>, Sarah Brofeldt <srhb@....dk>,
	Russ Anderson <rja@....com>, Dimitri Sivanich <sivanich@....com>,
	Hou Wenlong <houwenlong.hwl@...group.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Baoquan He <bhe@...hat.com>, Yuntao Wang <ytcoode@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Joerg Roedel <jroedel@...e.de>,
	Michael Roth <michael.roth@....com>
Subject: Re: [PATCH 0/3] Resolve problems with kexec identity mapping

On Mon, Jun 24, 2024 at 10:13:44AM -0500, Steve Wahl wrote:
> These accesses are a problem because they happen prior to establishing
> the page fault interrupt handler that would mend the identity map.  I
> know very little about the AMD SEV feature but reading the code I
> think it may be required to do this before setting up that handler.

Yeah, from looking at it, we should be able to establish a #PF handler that
early too but the devil's in the detail, especially in that early boot code.

Lemme poke some things and people...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette