linux-kernel - Re: [PATCHv6 25/30] x86/tdx: Make pages shared in ioremap()

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Message-ID: <87tubwd4y6.ffs@tglx>
Date:   Thu, 17 Mar 2022 15:33:21 +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 25/30] x86/tdx: Make pages shared in ioremap()

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:
> In TDX guests, guest memory is protected from host access. If a guest
> performs I/O, it needs to explicitly share the I/O memory with the host.
>
> Make all ioremap()ed pages that are not backed by normal memory
> (IORES_DESC_NONE or IORES_DESC_RESERVED) mapped as shared.
>
> The permissions in PAGE_KERNEL_IO already work for "decrypted" memory
> on AMD SEV/SME systems.  That means that they have no need to make a
> pgprot_decrypted() call.
>
> TDX guests, on the other hand, _need_ change to PAGE_KERNEL_IO for
> "decrypted" mappings.  Add a pgprot_decrypted() for TDX.
>
> Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

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