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authorAaron Durbin <adurbin@chromium.org>2017-03-08 11:23:11 -0600
committerAaron Durbin <adurbin@chromium.org>2017-03-09 19:15:03 +0100
commiteeb77379e03d868a52d42cd4f0dfba8d11c3d337 (patch)
treeb9517f0bbaee0ebb310867e5b183dff8ad737a5f /src/vboot/misc.h
parent1b9fc9e801d81fab7e26c0321c638dee83ca44a9 (diff)
vboot/tpm2: enable nvmem commits on cr50 when writing firmware secdata
cr50 by default delays nvmem commits internally from the point of reset to accumulate change state. However, the factory process can put a board into dev mode through the recovery screen. This state is stored in the TPM's nvmem space. When the factory process is complete a disable_dev_request and battery_cutoff_request is performed. This leads to disabling the dev mode in TPM, but the battery is subsequently cut off so the nvmem contents never stick. Therefore, whenever antirollback_write_space_firmware() is called we know there was a change in secdata so request cr50 to immediately enable nvmem commits going forward. This allows state changes to happen immediately. The fallout from this is that when secdata is changed that current boot will take longer because every transaction that writes to TPM nvmem space will perform a write synchronously. All subsequent boots do not have that effect. It should also be noted that this approach to the implementation is a pretty severe layering violation. However, the current TPM APIs don't lend themselves well to extending commands or re-using code outside of the current routines which inherently assume all knowledge of every command (in conflict with vendor commands since those are vendor-specific by definition). BUG=b:35775104 BRANCH=reef TEST=Confirmed disablement of dev mode sticks in the presence of: crossystem disable_dev_request=1; crossystem battery_cutoff_request=1; reboot; Change-Id: I3395db9cbdfea45da1f5cb994c6570978593b944 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/18681 Reviewed-by: Duncan Laurie <dlaurie@chromium.org> Tested-by: build bot (Jenkins)
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