Hi, Dave,
On 2/9/24 12:17, Dave Jiang wrote:
On 2/9/24 12:18 PM, Fenghua Yu wrote:
If Event Log is supported, upon completion of the Enable Device command,
the Event Log head in the variable idxd->evl->head should be cleared to
match the state of the EVLSTATUS register. But the variable is not reset
currently, leading mismatch of the variable and the register state.
The mismatch causes incorrect processing of Event Log entries.
Fix the issue by clearing the variable after completion of the command.
Should this be done in idxd_device_clear_state() instead?
If clear evl->head in idxd_device_clear_state(), evl->head still
mismatches head in EVLSTATUS in some cases.
For exmample, when a few event log entries are logged and then device is
disabled, head in EVLSTATUS is still a valid non-zero value. Clearing
evl->head in idxd_device_clear_state() when disabling device makes
evl->head and head in EVLSTATUS mismatched.
I haven't thought a failure test case when they mismatch in these cases
though.
But while thinking evl->head more, I wonder why is it even needed?
head of event log can always be read from EVLSTATUS instead of from its
shadow evl->head. And reading head from EVLSTATUS won't degrade
performance because tail is always read from EVLSTATUS whenever head is
read (no matter from evl->head or from EVLSATUS).
To avoid any mismatch issue/trouble, I think the right fix is to remove
head definition in struct idxd_evl and always read head from EVLSTATUS.
Do you think this is the right fix?
Thanks.
-Fenghua
