linux-kernel - Re: [PATCH v2 0/4] tsm: Unified Measurement Register ABI for TVMs

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Message-ID: <8e188239-44d2-42ad-9fa9-b46ad0a5b5bb@linux.intel.com>
Date: Mon, 17 Mar 2025 16:15:12 -0700
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,
 Dionna Amalie Glaze <dionnaglaze@...gle.com>,
 James Bottomley <James.Bottomley@...senPartnership.com>,
 Dan Middleton <dan.middleton@...ux.intel.com>,
 Mikko Ylinen <mikko.ylinen@...ux.intel.com>
Subject: Re: [PATCH v2 0/4] tsm: Unified Measurement Register ABI for TVMs

Hi Cedric,

On 2/23/25 7:20 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 the TSM core, allowing TVM
> (TEE VM) guest drivers to expose measurement registers (MRs) as attributes
> (files) in sysfs. With this interface, applications can read and write
> (extend) MRs like regular files, enabling usages like configuration
> verification (e.g., verifying a TVM's configuration against digests stored
> in static/immutable MRs like MRCONFIGID on TDX or HOSTDATA on SEV) and
> runtime measurements (e.g., extending the measurement of a container image
> to an RTMR before running it).
>
> Patches included in this series:
>
> - Patch 1 adds TSM APIs for TVM guest drivers to register/expose MRs
>    through sysfs.
> - Patch 2 provides a sample module demonstrating the usage of the new TSM
>    APIs.
> - The remaining patches update the TDX guest driver to expose TDX MRs
>    through the new TSM APIs.

Any comment on the missing event log support? Extending the measurements
without logging the event should break the tractability feature. Can you add
info about why it is ok to just add extension support for now?


>
> [1]: https://lore.kernel.org/linux-coco/20241210-tsm-rtmr-v3-0-5997d4dbda73@intel.com/
>
> Signed-off-by: Cedric Xing <cedric.xing@...el.com>
> ---
> Changes in v2:
> - Added TSM_MR_MAXBANKS Kconfig option
> - Updated Kconfig dependency for TSM_REPORTS
> - Updated comments in include/linux/tsm.h
> - Updated drivers/virt/coco/tsm-mr.c to use `IS_BUILTIN()` for determining
>    if static buffer addresses can be converted to GPAs by `virt_to_phys()`
> - Renamed function `tdx_mcall_rtmr_extend()` -> `tdx_mcall_extend_rtmr()`
> - Link to v1: https://lore.kernel.org/r/20250212-tdx-rtmr-v1-0-9795dc49e132@intel.com
>
> ---
> Cedric Xing (4):
>        tsm: Add TVM Measurement Register support
>        tsm: Add TSM measurement sample code
>        x86/tdx: Add tdx_mcall_extend_rtmr() interface
>        x86/tdx: Expose TDX MRs through TSM sysfs 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                  |  17 +-
>   drivers/virt/coco/Makefile                 |   2 +
>   drivers/virt/coco/tdx-guest/Kconfig        |  24 +-
>   drivers/virt/coco/tdx-guest/tdx-guest.c    | 115 +++++++++
>   drivers/virt/coco/{tsm.c => tsm-core.c}    |   6 +-
>   drivers/virt/coco/tsm-mr.c                 | 383 +++++++++++++++++++++++++++++
>   include/linux/tsm.h                        |  65 +++++
>   samples/Kconfig                            |  13 +
>   samples/Makefile                           |   1 +
>   samples/tsm/Makefile                       |   2 +
>   samples/tsm/tsm_mr_sample.c                | 107 ++++++++
>   16 files changed, 789 insertions(+), 8 deletions(-)
> ---
> base-commit: d082ecbc71e9e0bf49883ee4afd435a77a5101b6
> change-id: 20250209-tdx-rtmr-255479667146
>
> Best regards,

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer