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Date:   Tue, 17 May 2022 10:45:16 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        Sean Christopherson <seanjc@google.com>,
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        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
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        Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCHv6 02/15] mm: Add support for unaccepted memory
Message-Id: <20220517104516.16fb0be5cb28153104b80654@linux-foundation.org>
In-Reply-To: <20220517153444.11195-3-kirill.shutemov@linux.intel.com>
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        <20220517153444.11195-3-kirill.shutemov@linux.intel.com>
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On Tue, 17 May 2022 18:34:31 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:

> UEFI Specification version 2.9 introduces the concept of memory
> acceptance. Some Virtual Machine platforms, such as Intel TDX or AMD
> SEV-SNP, require memory to be accepted before it can be used by the
> guest. Accepting happens via a protocol specific to the Virtual Machine
> platform.
> 
> ...
>
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -928,6 +928,14 @@ static inline bool is_page_hwpoison(struct page *page)
>  #define PG_offline	0x00000100
>  #define PG_table	0x00000200
>  #define PG_guard	0x00000400
> +#define PG_unaccepted	0x00000800

"For pages that are never mapped to userspace (and aren't PageSlab),
page_type may be used."

Is that true of these pages?