From 741a4ec186160b632b6e19d2ad9623bc0121ea5d Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 28 Sep 2017 22:37:08 +0200 Subject: [PATCH] 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: David Hildenbrand Message-Id: <20170928203708.9376-31-david@redhat.com> Reviewed-by: Richard Henderson Signed-off-by: Cornelia Huck --- target/s390x/cpu.c | 11 +++++++++-- target/s390x/sigp.c | 6 +++++- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c index 92f6707bcb..95f4283188 100644 --- a/target/s390x/cpu.c +++ b/target/s390x/cpu.c @@ -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", diff --git a/target/s390x/sigp.c b/target/s390x/sigp.c index 964c75a736..ac3f8e7dc2 100644 --- a/target/s390x/sigp.c +++ b/target/s390x/sigp.c @@ -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); -- 2.11.0