On Mon, Mar 25, 2024 at 9:23 AM Winkler, Tomas tomas.winkler@intel.com wrote:
+struct rpmb_frame {
u8 stuff[196];u8 key_mac[32];u8 data[256];u8 nonce[16];__be32 write_counter;__be16 addr;__be16 block_count;__be16 result;__be16 req_resp;+} __packed;
I haven't looked at the NVME or the UFS spec in detail. Although, I assume the above frame makes sense for those types of
interfaces/protocols too? The rpmb implementation in ufs, has drifted apart from eMMC. E.g. in UFS4.0:
- the frame is different - see struct ufs_arpmb_meta in
include/uapi/scsi/scsi_bsg_ufs.h,
- Additional extended header was added,
- the frame size is no longer 512Bytes (256Bytes meta info + 256Bytes data)
but 4k,
- there are 9 rpmb operations instead of 7,
- The atomicity requirement of the command sequence was waved, And
probably more differences that I forgot. This is why it is better to designated this as an eMMC-only implementation?
Thanks for the update.
To move forward here we can either 1. as you suggest make this an eMMC-only implementation, or 2. we could remove struct rpmb_frame from include/linux/rpmb.h to make the shuffled data more opaque.
Is it possible to find and route RPMB data to NVME and UFS devices without a common meeting point like the RPMB subsystem proposed here? If the answer is yes option 1 makes more sense since we'll add a missing capability to eMMC. If the answer is no option 2 makes sense for NVME and UFS even if we save the implementation for later.
As I wrote previously the original implementation has already resolved protocol differences (NVMe have also different byte ordering) for closed usecase of storing data (not the configuration) I believe the whole point here is to let TEE driver to store the data, regardless of the technology.
Agreed.
In addition I might be wrong but I don't see much value in eMMC as the UFS and NVMe are currently leading technologies.
This patchset addresses a problem on present platforms so it's not irrelevant.
Thanks, Jens