linux-kernel - Re: [PATCH v9 5/6] x86/sev: Add SNP-specific unaccepted memory support

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Message-ID: <1c934f15-cc86-714f-e9d7-d7fbe29890dc@amd.com>
Date:   Tue, 12 Sep 2023 09:49:05 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Christopher Schramm <linux@...hramm.eu>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Michael Roth <michael.roth@....com>,
        Joerg Roedel <jroedel@...e.de>,
        Dionna Glaze <dionnaglaze@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v9 5/6] x86/sev: Add SNP-specific unaccepted memory
 support

On 9/12/23 07:17, Kirill A. Shutemov wrote:
> On Thu, Sep 07, 2023 at 11:50:15AM -0500, Tom Lendacky wrote:
>>>   From a quick look at
>>>
>>>     [PATCHv14 9/9] x86/tdx: Add unaccepted memory support
>>>
>>> it actually seems very similar for INTEL_TDX_GUEST.
>>>
>>> Ideally UNACCEPTED_MEMORY would not assume EFI either, but the
>>> implementation actually clearly does.
>>
>> @Kirill, is this something you are interested in having as well?
> 
> Unaccepted memory is an EFI feature I don't see how UNACCEPTED_MEMORY can
> be untied from EFI. If there's other (non-EFI) environment that has
> similar concept, sure we can try to generalize it beyond EFI.

Sorry, didn't mean to include the EFI related statement there. Agreed that 
unaccepted memory is only an EFI feature right now.

> 
> TDX guest is only runs with EFI firmware so far, so depending onf EFI and
> EFI_STUB is fine for TDX>

Right, SEV initially only ran on EFI firmware, but others have managed to 
get it working in other environments. So I was just wondering if you would 
also want to split the UNACCEPTED_MEMORY out for TDX similar to what was 
suggested for SEV.

Thanks,
Tom

>