[OpenSBI] rfence related question

[Leo Liang]

Hi,

I am studying the rfence part of OpenSBI recently.

>From what I understand the mechanism of the IPI framework is 
to do "update" to update the IPI information for remote harts,
and then send IPI through "ipi_dev" device to remote harts sequentially.

After the first IPI is sent (let's say from hart 0 to hart 1), 
hart 0 waits in the "sync" for the remote hart(hart 1) to do "process".
Hart 0 waits until the per hart tlb_sync flag is set from the remote hart(hart1) after "process" is done, 
and then keep on sending the next IPI to hart 2, and then hart 3 ... etc. 

If I understand it correctly, then would the following scenario have the possibility to occur?

In Linux, Hart 0 executes remote I cache flush instruction and sends IPI to hart 1;
At the meantime, hart 2 executes the same instruction and tries to send IPI to hart 0.
 
Both hart 0 and hart 2 step into m-mode, their mstatus.mie are disabled,
so, when hart 0 tries to send IPI to hart 2 and wait for the sync, deadlock happens.
Hart 0 is waiting for hart 2 and hart 2 is also waiting for hart 0 indefinitely because the interrupts being disabled.

Is this case likely to happen?

Best regards,
Leo