Re: [PATCH v2 02/12] mm: Introduce a function to check for virtualization protection features

Borislav Petkov
2021-08-14T18:32:20Z

On Fri, Aug 13, 2021 at 11:59:21AM -0500, Tom Lendacky wrote:
> In prep for other protected virtualization technologies, introduce a
> generic helper function, prot_guest_has(), that can be used to check
> for specific protection attributes, like memory encryption. This is
> intended to eliminate having to add multiple technology-specific checks
> to the code (e.g. if (sev_active() || tdx_active())).
>
> Reviewed-by: Joerg Roedel <jroedel@suse.de>
> Co-developed-by: Andi Kleen <ak@linux.intel.com>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
> arch/Kconfig | 3 +++
> include/linux/protected_guest.h | 35 +++++++++++++++++++++++++++++++++
> 2 files changed, 38 insertions(+)
> create mode 100644 include/linux/protected_guest.h
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 98db63496bab..bd4f60c581f1 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1231,6 +1231,9 @@ config RELR
> config ARCH_HAS_MEM_ENCRYPT
> bool
>
> +config ARCH_HAS_PROTECTED_GUEST
> + bool
> +
> config HAVE_SPARSE_SYSCALL_NR
> bool
> help
> diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
> new file mode 100644
> index 000000000000..43d4dde94793
> --- /dev/null
> +++ b/include/linux/protected_guest.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Protected Guest (and Host) Capability checks
> + *
> + * Copyright (C) 2021 Advanced Micro Devices, Inc.
> + *
> + * Author: Tom Lendacky <thomas.lendacky@amd.com>
> + */
> +
> +#ifndef _PROTECTED_GUEST_H
> +#define _PROTECTED_GUEST_H
> +
> +#ifndef __ASSEMBLY__
^^^^^^^^^^^^^

Do you really need that guard? It builds fine without it too. Or
something coming later does need it...?

--
Regards/Gruss,
Boris.