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[v2,4/4] spapr/rtas: do not reset the MSR in stop-self command

Message ID 20171009154930.29095-5-clg@kaod.org
State New
Headers show
Series disable the decrementer interrupt when a CPU is unplugged | expand

Commit Message

Cédric Le Goater Oct. 9, 2017, 3:49 p.m. UTC 
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>
---
 hw/ppc/spapr_rtas.c | 10 ----------
 1 file changed, 10 deletions(-)
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Patch

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index dfdbf1e2c6f8..dc825bc58263 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -210,16 +210,6 @@  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;
 
     /* Don't let the decremeter run on a CPU being stopped. This could
      * deliver an interrupt on a dying CPU and crash the guest.