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spapr/rtas: do not reset the MSR in stop-self command 

When a CPU is stopped with the 'stop-self' RTAS call, its state
'halted' is switched to 1 and, in this case, the MSR is not taken into
account anymore in the cpu_has_work() routine. Only the pending
hardware interrupts are checked with their LPCR:PECE* enablement bit.

The CPU is now also protected from the decrementer interrupt by the
LPCR:PECE* bits which are disabled in the 'stop-self' RTAS
call. Reseting the MSR is pointless.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Cédric Le Goater 2017-11-24 08:05:50 +01:00 committed by David Gibson
parent d6322252b3
commit 3fe4f0fc85
1 changed files with 0 additions and 10 deletions
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10
hw/ppc/spapr_rtas.c
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@ -206,16 +206,6 @@ static void rtas_stop_self(PowerPCCPU *cpu, sPAPRMachineState *spapr,
cs->halted = 1;
qemu_cpu_kick(cs);
/*
* While stopping a CPU, the guest calls H_CPPR which
* effectively disables interrupts on XICS level.
* However decrementer interrupts in TCG can still
* wake the CPU up so here we disable interrupts in MSR
* as well.
* As rtas_start_cpu() resets the whole MSR anyway, there is
* no need to bother with specific bits, we just clear it.
*/
env->msr = 0;
/* Disable Power-saving mode Exit Cause exceptions for the CPU.
* This could deliver an interrupt on a dying CPU and crash the