From: Kiryl Shutsemau <kas@kernel.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, Borislav Petkov <bp@alien8.de>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Subject: Re: [PATCH v2 2/3] x86/boot: Move unaccepted memory handling out of the decompressor
Date: Fri, 25 Sep 2026 12:59:17 +0100 [thread overview]
Message-ID: <arZh_KWXq7-kmwiw@thinkstation> (raw)
In-Reply-To: <20260925075137.44298-7-ardb@kernel.org>
On Fri, Sep 25, 2026 at 09:51:40AM +0200, Ard Biesheuvel wrote:
> arch_accept_memory() is an arch-specific hook that is required by the
> EFI stub when processing memory that the firmware reports to the OS as
> EFI_UNACCEPTED_MEMORY.
>
> This hook is called after ExitBootServices() has been called, as before
> that point, the EFI memory map may get updated behind the back of the
> running EFI stub, making it difficult to get a stable view on it while
> iterating over the entries.
>
> Currently, the x86 version of this hook is implemented in its
> decompressor rather than in the EFI stub itself, in a manner that is
> problematic: when an error occurs, it calls the decompressor's error()
> routine, but without having gone through the decompressor initialization
> code. This means it will resort to direct port I/O rather than the
> hypercall based interface that TDX guests would use otherwise.
>
> Conceptually, code that is only called from the EFI stub, and never by
> the decompressor when doing legacy boot, belongs in the EFI stub and not
> in the decompressor.
>
> So move it into the x86-specific EFI stub code, replacing the error() on
> the TDX path with tdx_panic(), and dropping the error() when no CC
> support is detected - the kernel can decide what to do in this case
> after it has booted.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2026-09-25 11:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 7:51 [PATCH v2 0/3] Move memory acceptance x86 arch code into EFI stub Ard Biesheuvel
2026-09-25 7:51 ` [PATCH v2 1/3] x86/tdx: Share tdx_panic() with the " Ard Biesheuvel
2026-09-25 11:44 ` Kiryl Shutsemau
2026-09-25 7:51 ` [PATCH v2 2/3] x86/boot: Move unaccepted memory handling out of the decompressor Ard Biesheuvel
2026-09-25 11:59 ` Kiryl Shutsemau [this message]
2026-09-25 7:51 ` [PATCH v2 3/3] x86/boot: Drop unused implementation of panic() Ard Biesheuvel
2026-09-29 3:01 ` [PATCH v2 0/3] Move memory acceptance x86 arch code into EFI stub Borislav Petkov
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