On 4/23/26 6:43 AM, Arun Menon wrote:
On Wed, Apr 08, 2026 at 11:34:54AM +0300, Jarkko Sakkinen wrote:
On Tue, Mar 24, 2026 at 06:11:11PM +0530, Arun Menon wrote:
Hi Jarkko,
On Tue, Mar 24, 2026 at 12:41:26PM +0200, Jarkko Sakkinen wrote:
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
64kb? I am only increasing the TPM buffer to 8kb. More does not seem to
be necessary.
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?
The QEMU patches are in review at the moment,
here is the link:
https://lore.kernel.org/qemu-devel/[email protected]/
Hoping to have them merged soon.
Right, and additional question: what about swtpm?
I am waiting for https://github.com/trustedComputingGroup/tpm to show
rev185 with PQC support so that I can merge my patches based on 'their'
PQC support into the public libtpms repo.
