linux-kernel - Re: [PATCH] efi: pstore: Support late setup with TEE-backed efivars ops

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Message-ID: <202512041535.AA6065A38@keescook>
Date: Thu, 4 Dec 2025 15:36:08 -0800
From: Kees Cook <kees@...nel.org>
To: Val Packett <val@...kett.cool>
Cc: Tony Luck <tony.luck@...el.com>,
	"Guilherme G. Piccoli" <gpiccoli@...lia.com>,
	Ard Biesheuvel <ardb@...nel.org>, linux-hardening@...r.kernel.org,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] efi: pstore: Support late setup with TEE-backed efivars
 ops

On Wed, Dec 03, 2025 at 01:28:29AM -0300, Val Packett wrote:
> On some platforms, EFI variable services only become available when an
> appropriate TEE driver is initialized such as qseecom, gsmi or stmm.
> 
> This would work fine when efi_pstore was built as a module and loaded
> late by userspace, but with CONFIG_EFI_VARS_PSTORE=y this driver would
> quit due to non-writable efivars before the necessary driver had any
> chance to load.
> 
> Listen to efivar_ops_nh notifications and retry the initialization when
> writable EFI variable ops become available.
> 
> Signed-off-by: Val Packett <val@...kett.cool>

This seems fine to me, though I defer to Ard, who knows the EFI bits way
better than I do. :)

Acked-by: Kees Cook <kees@...nel.org>

-- 
Kees Cook