On Wed, 2026-09-30 at 14:43 +0100, Yeoreum Yun wrote: > Confidential computing guests without a TPM can use TSM measurement > registers to record IMA measurement digests instead of TPM PCRs.
Hi Yeoreum a similar patch set has been sent to the linux-integrity mailing list: https://lore.kernel.org/linux-integrity/[email protected]/ Could you please work with Gong Ruiqi to have a unified proposal? Thanks Roberto > This series introduces in-kernel interfaces for accessing TSM > measurement registers, abstracts IMA's measurement-register operations, > and adds a TSM backend for Intel TDX and Arm CCA. > > The following mappings between TPM PCR indices and TSM measurement > registers are defined for Intel TDX [0] and proposed for Arm CCA [1]: > > TPM PCR index | Intel TDX register | Arm CCA register > --------------+--------------------+----------------- > 0 | MRTD | RIM > 1, 7 | RTMR[0] | REM[0] > 2-6 | RTMR[1] | REM[1] > 8-15 | RTMR[2] | REM[2] > > These mappings allow IMA to translate PCR indices into the corresponding > TSM measurement registers. > > The TPM backend remains preferred when it is available at IMA > initialization. Otherwise, IMA falls back to a supported TSM backend. > Only one backend is selected; IMA measurements are not extended to both > TPM PCRs and TSM measurement registers. > > The attestation proccess for guest with TSM measurement register will > be done with Confidential Compute Event Log (CCEL) which is exported by > /sys/firmware/acpi/tables/data/CCEL. Here is brief process in arm64: > > Verifier Realm guest RMM / Platform > | | | > |--- Challenge (nonce) -->| | > | |--- Request token -------->| > | | with challenge | > | | | > | |<-- CCA token T -----------| > |<-- CCA token T ---------| | > |<-- CCEL event log ------| | > |<-- IMA measurement log -| | > | | | > Verify token T: | | > - signatures | | > - Platform/Realm | | > token binding | | > - challenge freshness | | > - platform/RIM policy | | > - verify measurement logs | | > | | | > | ----ACCEPT / REJECT---->| | > > This patch based on arm-cca-mr series [3]. > > Link: [0] > https://uefi.org/specs/UEFI/2.11/38_Confidential_Computing.html#intel-trust-domain-extension > Link: [1] https://github.com/tianocore/edk2/issues/11383 > Link: [2] https://github.com/tianocore/edk2/issues/11384 > Link: [3] > https://lore.kernel.org/all/[email protected]/ > > --- > Yeoreum Yun (3): > virt: coco: introduce tsm_default_tm() and tsm_mr_read()/write() > security: IMA: introduce ima_mr structure > security: IMA: use TSM measurement registers > > drivers/virt/coco/guest/tsm-mr.c | 159 +++++++++++++--- > include/linux/tsm-mr.h | 26 +++ > security/integrity/ima/Makefile | 3 +- > security/integrity/ima/ima.h | 7 +- > security/integrity/ima/ima_api.c | 4 +- > security/integrity/ima/ima_crypto.c | 137 +++++--------- > security/integrity/ima/ima_fs.c | 16 +- > security/integrity/ima/ima_init.c | 7 +- > security/integrity/ima/ima_mr.c | 48 +++++ > security/integrity/ima/ima_mr.h | 76 ++++++++ > security/integrity/ima/ima_mr_tpm.c | 155 ++++++++++++++++ > security/integrity/ima/ima_mr_tsm.c | 290 > ++++++++++++++++++++++++++++++ > security/integrity/ima/ima_queue.c | 39 ++-- > security/integrity/ima/ima_template.c | 4 +- > security/integrity/ima/ima_template_lib.c | 2 +- > 15 files changed, 819 insertions(+), 154 deletions(-) > --- > base-commit: b561246f45174b7472c24b75358ea95bae72b7b8 > change-id: 20260929-ima_tgx_integration_v2-1c54aeeaeaee > > Best regards,
