On Mon, May 18, 2026 at 08:47:18PM +0530, Arun Menon wrote: > The new version of TCG TPM v185 [1] supports sending data/commands in > chunks for the CRB (Command Response Buffer) interface. This is in line > with the initiative to support PQC algorithms. > > This series implements the logic to send and receive larger TPM > cmd/rsp between the linux guest and the TPM backend in chunks. > Currently, the TPM CRB driver is limited by the physical size of the > MMIO window. When userspace attempts to send a payload that exceeds this > size, the driver rejects it. > > This series introduces chunking support. The driver now checks the CRB > interface capability for CRB_INTF_CAP_CRB_CHUNK. If supported by the > backend, the driver will slice oversized commands into MMIO-sized > chunks, signalling the backend via CRB_START_NEXT_CHUNK, and finalizing > with CRB_START_INVOKE. Responses are also read back in a similar chunked > manner. > > If the backend does not support chunking, the driver retains its legacy > behaviour and enforces the standard size limits. > > This feature also requires the QEMU to interpret the data in chunks and > forward it to the TPM backend and subsequently dispatch the TPM response > in chunks back to the linux guest. This is implemented in [2] > > This series depends on Jarkko's unmerged patch from the mailing list: > [PATCH v9 11/11] tpm-buf: Implement managed allocations. > > Depends-on: > <http://lore.kernel.org/[email protected]>
I'll rebase this to the latest master so that it can be included to the series. > > The whole series applied on top of for-next-tpm branch (with prerequisite) > can be found here: > https://github.com/armenon-rh/linux/tree/tpm-crb-linux > > [1] > https://trustedcomputinggroup.org/wp-content/uploads/PC-Client-Specific-Platform-TPM-Profile-for-TPM-2p0-v1p07_Pub.pdf > [2] > https://lore.kernel.org/qemu-devel/[email protected]/ > > v3 > -- > - Split patch 2, so that the code is cleaner. > - Re-order the buffer size adjustment patch. > - Rename crb_trigger_tpm to tpm_crb_start. > - Add dispatching logic in send and recv functions. Chunking is > separated from no-chunking for clarity. > - Increase TPM_BUFSIZE in the common file include/linux/tpm.h following, > [PATCH v9 11/11] tpm-buf: Implement managed allocations > > https://lore.kernel.org/linux-integrity/[email protected]/ > > v2 > -- > - Add size checks before copying memory. > - Update TPM_BUFSIZE to 8KB. > - Commit messages updated to indicate motivation and logic of the change. > > Arun Menon (6): > tpm_crb: Add register definitions of TPM CRB chunking fields > tpm_crb: Split start method into a separate header > tpm_crb: Add start_cmd parameter to tpm_crb_start wrapper > tpm: tis_i2c: Use local 4KB buffer to limit memory usage > tpm: Increase TPM_BUFSIZE to 8kB for chunking support > tpm_crb: Implement command and response chunking logic > > drivers/char/tpm/tpm_crb.c | 257 +++++++++++++++++++++++++-------- > drivers/char/tpm/tpm_tis_i2c.c | 6 +- > include/linux/tpm.h | 2 +- > 3 files changed, 204 insertions(+), 61 deletions(-) > > -- > 2.54.0 > BR, Jarkko
