Commit 741a4ec1 authored by David Hildenbrand's avatar David Hildenbrand Committed by Cornelia Huck
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target/s390x: special handling when starting a CPU with WAIT PSW 



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: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20170928203708.9376-31-david@redhat.com>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent f74990a5

target/s390x/cpu.c

+9 −2
Original line number Diff line number Diff line
@@ -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 */

        /*

         * 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",

target/s390x/sigp.c

+5 −1
Original line number Diff line number Diff line
@@ -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);