x86/tdx: Add tdx_mcall_extend_rtmr() interface

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The TDX guest exposes one MRTD (Build-time Measurement Register) and four
RTMR (Run-time Measurement Register) registers to record the build and boot
measurements of a virtual machine (VM). These registers are similar to PCR
(Platform Configuration Register) registers in the TPM (Trusted Platform
Module) space. This measurement data is used to implement security features
like attestation and trusted boot.

To facilitate updating the RTMR registers, the TDX module provides support
for the `TDG.MR.RTMR.EXTEND` TDCALL which can be used to securely extend
the RTMR registers.

Add helper function to update RTMR registers. It will be used by the TDX
guest driver in enabling RTMR extension support.

Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Cedric Xing <cedric.xing@intel.com>
Acked-by: Dionna Amalie Glaze <dionnaglaze@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20250506-tdx-rtmr-v6-3-ac6ff5e9d58a@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

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Cedric Xing 2025-05-06 17:57:09 -05:00 • committed by Dan Williams

parent f6953f1f9e

commit 3f88ca9614

3 changed files with 40 additions and 0 deletions

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37

arch/x86/coco/tdx/tdx.c

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arch/x86/include/asm/shared/tdx.h

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arch/x86/include/asm/tdx.h

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