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target/ppc: Detect erroneous condition in interrupt delivery

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It's very easy for the CPU specific has_work() implementation
and the logic in ppc_hw_interrupt() to be subtly out of sync.

This can occasionally allow a CPU to wakeup from a PM state
and resume executing past the PM instruction when it should
resume at the 0x100 vector.

This detects if it happens and aborts, making it a lot easier
to catch such bugs when testing rather than chasing obscure
guest misbehaviour.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20190215161648.9600-8-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Benjamin Herrenschmidt 2019-02-15 17:16:45 +01:00 committed by David Gibson
parent a790e82b13
commit f8154fd22b
1 changed files with 16 additions and 0 deletions
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16
target/ppc/excp_helper.c
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@ -878,6 +878,22 @@ static void ppc_hw_interrupt(CPUPPCState *env)
return;
}
}
if (env->resume_as_sreset) {
/*
* This is a bug ! It means that has_work took us out of halt without
* anything to deliver while in a PM state that requires getting
* out via a 0x100
*
* This means we will incorrectly execute past the power management
* instruction instead of triggering a reset.
*
* It generally means a discrepancy between the wakup conditions in the
* processor has_work implementation and the logic in this function.
*/
cpu_abort(CPU(ppc_env_get_cpu(env)),
"Wakeup from PM state but interrupt Undelivered");
}
}
void ppc_cpu_do_system_reset(CPUState *cs)