| commit | 84a680b3cfff516bcd7e37de23f656003c213062 | [log] [tgz] |
|---|---|---|
| author | Martin Lueker-Boden <martin.lueker-boden@wdc.com> | Thu Aug 18 15:23:36 2022 -0700 |
| committer | Martin Lueker-Boden <47870387+martin-lueker@users.noreply.github.com> | Sun Aug 21 14:11:15 2022 -0700 |
| tree | a5b9748a389527bdeaded8b1f5a447bad00ef113 | |
| parent | 3c2cf13118993e640a0711fe85502aae0a4f0d9e [diff] |
[entropy_src/rtl] Corrections to Main SM
This commit fixes a number of deviations from spec in the main SM
- The most important fixes come in the exit from the `ContHTRunning`
state. Previously this state moved to start SHA processing of
the raw entropy at the end of each HT window, regardless of the HT
results. Errors or alerts were to be handled in later states
as the SHA engine shut down. This had two big problems:
1. Data from failing windows would be permitted in the conditioned
output, rather than being blocked.
2. Since the SM clears the failure counter and issues the alert
from different states, there is a possiblity that an alert
can be cleared before action is taken. This provides a pathway
for the _release_ of low-grade entropy, with _no alert_.
- The `CondHTRunning` state also did not go straight to Idle once
disabled, instead it would close out the SHA processing pipline
first. (This "clean exit" was also the motivation for moving to SHA
processing even in HT error condictions). Unfortunately this is
the only situation where the SHA is shut down cleanly like this,
making it hard to predict whether old data will be squeezed from
the SHA or not.
- Having a full esfinal FIFO would cause the SM to take different
tranitions than normal. Given that this condition is impossible
to predict, this leads to unverifiable outputs.
- Though no data is to be output after the single BOOT mode seed
is generated, health test data still needs to be processed and
--unless in FW_OV mode-- alerts need to be signalled.
Signed-off-by: Martin Lueker-Boden <martin.lueker-boden@wdc.com>
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