On Tue, Mar 24, 2026 at 12:47:59PM +0530, Arun Menon wrote: > The new version of TCG TPM v185 (currently under review [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] > > [1] > https://trustedcomputinggroup.org/wp-content/uploads/PC-Client-Specific-Platform-TPM-Profile-for-TPM-2p0-v1p07_rc1_121225.pdf > [2] > https://lore.kernel.org/qemu-devel/[email protected]/ > > Arun Menon (4): > tpm_crb: Add definition of TPM CRB chunking fields > tpm_crb: Add new wrapper function to invoke start method > tpm_crb: Implement command and response chunking logic > tpm: Increase TPM_BUFSIZE to 64kB for chunking support > > drivers/char/tpm/tpm.h | 2 +- > drivers/char/tpm/tpm_crb.c | 194 ++++++++++++++++++++++++++----------- > 2 files changed, 137 insertions(+), 59 deletions(-) > > -- > 2.53.0 >
When QEMU has the feature available? BR, Jarkko
