linux-kernel - Re: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 02 Feb 2022 01:25:28 +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,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

On Mon, Jan 24 2022 at 18:02, 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.
>
> Since TDX memory encryption support is similar to AMD SEV architecture,
> reuse the infrastructure from AMD SEV code.
>
> Add tdx_shared_mask() interface to get the TDX guest shared bitmask.
>
> pgprot_decrypted() is used by drivers (i915, virtio_gpu, vfio). Export
> both pgprot_encrypted() and pgprot_decrypted().

How so?

# git grep pgprot_encrypted
arch/x86/include/asm/pgtable.h:#define pgprot_encrypted(prot)   __pgprot(__sme_set(pgprot_val(prot)))
arch/x86/mm/ioremap.c:          prot = pgprot_encrypted(prot);
arch/x86/mm/ioremap.c:  return encrypted_prot ? pgprot_encrypted(prot)
arch/x86/mm/mem_encrypt_amd.c:          protection_map[i] = pgprot_encrypted(protection_map[i]);
arch/x86/mm/pat/set_memory.c:           cpa.mask_clr = pgprot_encrypted(cpa.mask_clr);
arch/x86/platform/efi/quirks.c:                           pgprot_val(pgprot_encrypted(FIXMAP_PAGE_NORMAL)));
fs/proc/vmcore.c:       prot = pgprot_encrypted(prot);
include/linux/pgtable.h:#ifndef pgprot_encrypted
include/linux/pgtable.h:#define pgprot_encrypted(prot)  (prot)

I cannot find any of the above mentioned subsystems in this grep
output. Neither does this patch add any users which require those
exports.

Thanks,

        tglx