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target/s390x: special handling when starting a CPU with WAIT PSW

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When we try to start a CPU with a WAIT PSW, we have to take care that
TCG will actually try to continue executing instructions.

We must therefore really only unhalt the CPU if we don't have a WAIT
PSW. Also document the special order for restart interrupts, which
load a new PSW and change the state to operating.

To keep KVM working, simply don't have a look at the WAIT bit when
loading the PSW. Otherwise the behavior of a restart interrupt when
a CPU stopped would be changed.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170928203708.9376-31-david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
David Hildenbrand 2017-09-28 22:37:08 +02:00 committed by Cornelia Huck
parent f74990a5d0
commit 741a4ec186
2 changed files with 14 additions and 3 deletions
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11
target/s390x/cpu.c
View File

@ -337,8 +337,15 @@ unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu)
break;
case CPU_STATE_OPERATING:
case CPU_STATE_LOAD:
/* unhalt the cpu for common infrastructure */
s390_cpu_unhalt(cpu);
/*
* Starting a CPU with a PSW WAIT bit set:
* KVM: handles this internally and triggers another WAIT exit.
* TCG: will actually try to continue to run. Don't unhalt, will
* be done when the CPU actually has work (an interrupt).
*/
if (!tcg_enabled() || !(cpu->env.psw.mask & PSW_MASK_WAIT)) {
s390_cpu_unhalt(cpu);
}
break;
default:
error_report("Requested CPU state is not a valid S390 CPU state: %u",

6
target/s390x/sigp.c
View File

@ -232,8 +232,12 @@ static void sigp_restart(CPUState *cs, run_on_cpu_data arg)
case CPU_STATE_STOPPED:
/* the restart irq has to be delivered prior to any other pending irq */
cpu_synchronize_state(cs);
do_restart_interrupt(&cpu->env);
/*
* Set OPERATING (and unhalting) before loading the restart PSW.
* load_psw() will then properly halt the CPU again if necessary (TCG).
*/
s390_cpu_set_state(CPU_STATE_OPERATING, cpu);
do_restart_interrupt(&cpu->env);
break;
case CPU_STATE_OPERATING:
cpu_inject_restart(cpu);