linux-kernel - Re: [PATCHv6 26/30] x86/mm/cpa: Add support for TDX shared memory

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Message-ID: <87o824d3uz.ffs@tglx>
Date:   Thu, 17 Mar 2022 15:56:52 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...el.com,
        luto@...nel.org, peterz@...radead.org
Cc:     sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        thomas.lendacky@....com, brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv6 26/30] x86/mm/cpa: Add support for TDX shared memory

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:

> Intel TDX protects guest memory from VMM access. Any memory that is
> required for communication with the VMM must be explicitly shared.
>
> It is a two-step process: the guest sets the shared bit in the page
> table entry and notifies VMM about the change. The notification happens
> using MapGPA hypercall.
>
> Conversion back to private memory requires clearing the shared bit,
> notifying VMM with MapGPA hypercall following with accepting the memory
> with AcceptPage hypercall.
>
> Provide a TDX version of x86_platform.guest.* callbacks. It makes
> __set_memory_enc_pgtable() work right in TDX guest.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>