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From:   Dionna Amalie Glaze <dionnaglaze@google.com>
Date:   Tue, 31 Jan 2023 08:08:04 -0800
Message-ID: <CAAH4kHaqObDRfKAzM8tTrhmQWZx7w2oTP=YJOo=fCG1kHDvj8w@mail.gmail.com>
Subject: Re: [PATCH v2, RESEND] x86/efi: Safely enable unaccepted memory in UEFI
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-kernel@vger.kernel.org, x86@vger.kernel.org,
        linux-efi@vger.kernel.org, "Min M. Xu" <min.m.xu@intel.com>,
        Gerd Hoffmann <kraxel@redhat.com>,
        James Bottomley <jejb@linux.ibm.com>,
        Tom Lendacky <Thomas.Lendacky@amd.com>,
        Jiewen Yao <jiewen.yao@intel.com>,
        Erdem Aktas <erdemaktas@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>
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> > +       efi_status_t status;
> > +
> > +       if (!IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
>
> Do we need to check for IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) here as well?
>

Arguably no, since the firmware should only make the protocol
available when it determines that the protocol should be used. In our
case, that's just SEV-SNP. The firmware's TDX logic will not expose
this protocol.

This maintains flexibility for the rare case that the TDX go-to-market
schedule doesn't align with upstream's acceptance of unaccepted memory
support, but does accept the generic TDX support. Best not paint
ourselves into a corner.

-- 
-Dionna Glaze, PhD (she/her)