linux-kernel - Re: [PATCH 0/4] tsm: Unified Measurement Register ABI for TVMs

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Message-ID: <42c5eba9-381b-4639-9131-f645b375d235@linux.intel.com>
Date: Mon, 17 Feb 2025 17:10:10 -0800
From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Cedric Xing <cedric.xing@...el.com>,
 Dan Williams <dan.j.williams@...el.com>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, x86@...nel.org,
 "H. Peter Anvin" <hpa@...or.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev
Subject: Re: [PATCH 0/4] tsm: Unified Measurement Register ABI for TVMs


On 2/12/25 6:23 PM, Cedric Xing wrote:
> NOTE: This patch series introduces the Measurement Register (MR) ABI, and
> is a continuation of the RFC series on the same topic [1].
>
> This patch series adds a unified interface to TSM core for confidential
> computing (CC) guest drivers to provide access to measurement registers
> (MRs), which are essential for relying parties (RPs) to verify the
> integrity of the computing environment. The interface is structured around

I recommend adding information about possible use cases and how end
users might use it here.

> `struct tsm_measurement`, which holds an array of `struct
> tsm_measurement_register` and includes operations for reading and updating
> MRs.
>
> Each `struct tsm_measurement_register` features a `mr_flags` member that
> indicates the MR's properties, such as *Readable* (`TSM_MR_F_R`),
> *Extensible* (`TSM_MR_F_X`), etc. Please refer to Patch 1 in this series
> for more details. Patch 2 adds a sample module to demonstrate how to define
> and implement MRs in a CC guest driver. The last patches add TDX MR support
> to the TDX Guest driver.
>
> MRs are made accessible to applications through a directory tree (rooted at
> `/sys/kernel/tsm`). An MR could be presented as either a file containing
> its value, or a directory containing the file `digest` under a subdirectory
> of the same name as the hash algorithm. By default, an MR will be presented
> as a directory unless `TSM_MR_F_F` is set in `mr_flags`.
>
> [1]:https://lore.kernel.org/linux-coco/20241210-tsm-rtmr-v3-0-5997d4dbda73@intel.com/

I know that this patch set does not support event log extension for RTMR 
extend.
May be you can add some info about why we cannot support it now and any 
issues
with not supporting it now.

> Signed-off-by: Cedric Xing<cedric.xing@...el.com>
> ---
> Cedric Xing (3):
>        tsm: Add TVM Measurement Register support
>        tsm: Add TSM measurement sample code
>        x86/tdx: Expose TDX MRs through TSM sysfs interface
>
> Kuppuswamy Sathyanarayanan (1):
>        x86/tdx: Add tdx_mcall_rtmr_extend() interface
>
>   Documentation/ABI/testing/sysfs-kernel-tsm |  20 ++
>   MAINTAINERS                                |   3 +-
>   arch/x86/coco/tdx/tdx.c                    |  36 +++
>   arch/x86/include/asm/shared/tdx.h          |   1 +
>   arch/x86/include/asm/tdx.h                 |   2 +
>   drivers/virt/coco/Kconfig                  |   3 +-
>   drivers/virt/coco/Makefile                 |   2 +
>   drivers/virt/coco/tdx-guest/Kconfig        |  15 ++
>   drivers/virt/coco/tdx-guest/tdx-guest.c    | 119 +++++++++
>   drivers/virt/coco/{tsm.c => tsm-core.c}    |   6 +-
>   drivers/virt/coco/tsm-mr.c                 | 375 +++++++++++++++++++++++++++++
>   include/linux/tsm.h                        |  64 +++++
>   samples/Kconfig                            |  10 +
>   samples/Makefile                           |   1 +
>   samples/tsm/Makefile                       |   2 +
>   samples/tsm/tsm_mr_sample.c                | 107 ++++++++
>   16 files changed, 763 insertions(+), 3 deletions(-)
> ---
> base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
> change-id: 20250209-tdx-rtmr-255479667146
>
> Best regards,

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer