We can add a variable instead of scanning all online VCPUs to know how many are started. We can't trivially tell which VCPU is the last one, though.
Suggested-by: Cornelia Huck <[email protected]> Signed-off-by: Radim Krčmář <[email protected]> --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/kvm-s390.c | 39 +++++++++++++++------------------------ 2 files changed, 16 insertions(+), 24 deletions(-) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index a409d5991934..be0d0bdf585b 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -735,6 +735,7 @@ struct kvm_arch{ struct mutex ipte_mutex; struct ratelimit_state sthyi_limit; spinlock_t start_stop_lock; + unsigned started_vcpus; struct sie_page2 *sie_page2; struct kvm_s390_cpu_model model; struct kvm_s390_crypto crypto; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 9f23a9e81a91..1534778a3c66 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3414,25 +3414,17 @@ static void __enable_ibs_on_vcpu(struct kvm_vcpu *vcpu) void kvm_s390_vcpu_start(struct kvm_vcpu *vcpu) { - int i, online_vcpus, started_vcpus = 0; - if (!is_vcpu_stopped(vcpu)) return; trace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 1); /* Only one cpu at a time may enter/leave the STOPPED state. */ spin_lock(&vcpu->kvm->arch.start_stop_lock); - online_vcpus = atomic_read(&vcpu->kvm->online_vcpus); - for (i = 0; i < online_vcpus; i++) { - if (!is_vcpu_stopped(vcpu->kvm->vcpus[i])) - started_vcpus++; - } - - if (started_vcpus == 0) { + if (vcpu->kvm->arch.started_vcpus == 0) { /* we're the only active VCPU -> speed it up */ __enable_ibs_on_vcpu(vcpu); - } else if (started_vcpus == 1) { + } else if (vcpu->kvm->arch.started_vcpus == 1) { /* * As we are starting a second VCPU, we have to disable * the IBS facility on all VCPUs to remove potentially @@ -3441,6 +3433,8 @@ void kvm_s390_vcpu_start(struct kvm_vcpu *vcpu) __disable_ibs_on_all_vcpus(vcpu->kvm); } + vcpu->kvm->arch.started_vcpus++; + atomic_andnot(CPUSTAT_STOPPED, &vcpu->arch.sie_block->cpuflags); /* * Another VCPU might have used IBS while we were offline. @@ -3453,16 +3447,12 @@ void kvm_s390_vcpu_start(struct kvm_vcpu *vcpu) void kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu) { - int i, online_vcpus, started_vcpus = 0; - struct kvm_vcpu *started_vcpu = NULL; - if (is_vcpu_stopped(vcpu)) return; trace_kvm_s390_vcpu_start_stop(vcpu->vcpu_id, 0); /* Only one cpu at a time may enter/leave the STOPPED state. */ spin_lock(&vcpu->kvm->arch.start_stop_lock); - online_vcpus = atomic_read(&vcpu->kvm->online_vcpus); /* SIGP STOP and SIGP STOP AND STORE STATUS has been fully processed */ kvm_s390_clear_stop_irq(vcpu); @@ -3470,19 +3460,20 @@ void kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu) atomic_or(CPUSTAT_STOPPED, &vcpu->arch.sie_block->cpuflags); __disable_ibs_on_vcpu(vcpu); - for (i = 0; i < online_vcpus; i++) { - if (!is_vcpu_stopped(vcpu->kvm->vcpus[i])) { - started_vcpus++; - started_vcpu = vcpu->kvm->vcpus[i]; - } - } + vcpu->kvm->arch.started_vcpus--; + + if (vcpu->kvm->arch.started_vcpus == 1) { + struct kvm_vcpu *started_vcpu; - if (started_vcpus == 1) { /* - * As we only have one VCPU left, we want to enable the - * IBS facility for that VCPU to speed it up. + * As we only have one VCPU left, we want to enable the IBS + * facility for that VCPU to speed it up. */ - __enable_ibs_on_vcpu(started_vcpu); + kvm_for_each_vcpu(i, started_vcpu, vcpu->kvm) + if (!is_vcpu_stopped(started_vcpu)) { + __enable_ibs_on_vcpu(started_vcpu); + break; + } } spin_unlock(&vcpu->kvm->arch.start_stop_lock); -- 2.13.3
