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[Qemu-devel] [PATCH for-2.12 v3 3/3] spapr/rtas: do not reset the MSR in

From: Cédric Le Goater
Subject: [Qemu-devel] [PATCH for-2.12 v3 3/3] spapr/rtas: do not reset the MSR in stop-self command
Date: Mon, 20 Nov 2017 11:03:47 +0100

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 <address@hidden>
Reviewed-by: David Gibson <address@hidden>
 hw/ppc/spapr_rtas.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index b5cff3ab29d3..7ddddc1c9c8a 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -204,16 +204,6 @@ static void rtas_stop_self(PowerPCCPU *cpu, 
sPAPRMachineState *spapr,
     cs->halted = 1;
-    /*
-     * 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

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