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Commit 0759d068 authored by David Hildenbrand's avatar David Hildenbrand Committed by Christian Borntraeger
Browse files

KVM: s390: cleanup handle_wait by reusing kvm_vcpu_block 



This patch cleans up the code in handle_wait by reusing the common code
function kvm_vcpu_block.

signal_pending(), kvm_cpu_has_pending_timer() and kvm_arch_vcpu_runnable() are
sufficient for checking if we need to wake-up that VCPU. kvm_vcpu_block
uses these functions, so no checks are lost.

The flag "timer_due" can be removed - kvm_cpu_has_pending_timer() tests whether
the timer is pending, thus the vcpu is correctly woken up.

Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 6352e4d2

arch/s390/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -305,7 +305,6 @@ struct kvm_s390_local_interrupt { 
	struct list_head list;

	atomic_t active;

	struct kvm_s390_float_interrupt *float_int;

	int timer_due; /* event indicator for waitqueue below */

	wait_queue_head_t *wq;

	atomic_t *cpuflags;

	unsigned int action_bits;

arch/s390/kvm/interrupt.c

+5 −36
Original line number Diff line number Diff line
@@ -585,60 +585,32 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) 
int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)

{

	u64 now, sltime;

	DECLARE_WAITQUEUE(wait, current);



	vcpu->stat.exit_wait_state++;

	if (kvm_cpu_has_interrupt(vcpu))

		return 0;



	__set_cpu_idle(vcpu);

	spin_lock_bh(&vcpu->arch.local_int.lock);

	vcpu->arch.local_int.timer_due = 0;

	spin_unlock_bh(&vcpu->arch.local_int.lock);

	/* fast path */

	if (kvm_cpu_has_pending_timer(vcpu) || kvm_arch_vcpu_runnable(vcpu))

		return 0;



	if (psw_interrupts_disabled(vcpu)) {

		VCPU_EVENT(vcpu, 3, "%s", "disabled wait");

		__unset_cpu_idle(vcpu);

		return -EOPNOTSUPP; /* disabled wait */

	}



	__set_cpu_idle(vcpu);

	if (!ckc_interrupts_enabled(vcpu)) {

		VCPU_EVENT(vcpu, 3, "%s", "enabled wait w/o timer");

		goto no_timer;

	}



	now = get_tod_clock_fast() + vcpu->arch.sie_block->epoch;

	if (vcpu->arch.sie_block->ckc < now) {

		__unset_cpu_idle(vcpu);

		return 0;

	}



	sltime = tod_to_ns(vcpu->arch.sie_block->ckc - now);



	hrtimer_start(&vcpu->arch.ckc_timer, ktime_set (0, sltime) , HRTIMER_MODE_REL);

	VCPU_EVENT(vcpu, 5, "enabled wait via clock comparator: %llx ns", sltime);

no_timer:

	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

	spin_lock(&vcpu->arch.local_int.float_int->lock);

	spin_lock_bh(&vcpu->arch.local_int.lock);

	add_wait_queue(&vcpu->wq, &wait);

	while (list_empty(&vcpu->arch.local_int.list) &&

		list_empty(&vcpu->arch.local_int.float_int->list) &&

		(!vcpu->arch.local_int.timer_due) &&

		!signal_pending(current) &&

		!kvm_s390_si_ext_call_pending(vcpu)) {

		set_current_state(TASK_INTERRUPTIBLE);

		spin_unlock_bh(&vcpu->arch.local_int.lock);

		spin_unlock(&vcpu->arch.local_int.float_int->lock);

		schedule();

		spin_lock(&vcpu->arch.local_int.float_int->lock);

		spin_lock_bh(&vcpu->arch.local_int.lock);

	}

	kvm_vcpu_block(vcpu);

	__unset_cpu_idle(vcpu);

	__set_current_state(TASK_RUNNING);

	remove_wait_queue(&vcpu->wq, &wait);

	spin_unlock_bh(&vcpu->arch.local_int.lock);

	spin_unlock(&vcpu->arch.local_int.float_int->lock);

	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);



	hrtimer_try_to_cancel(&vcpu->arch.ckc_timer);
@@ -649,11 +621,8 @@ void kvm_s390_tasklet(unsigned long parm) 
{

	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) parm;



	spin_lock(&vcpu->arch.local_int.lock);

	vcpu->arch.local_int.timer_due = 1;

	if (waitqueue_active(&vcpu->wq))

		wake_up_interruptible(&vcpu->wq);

	spin_unlock(&vcpu->arch.local_int.lock);

}



/*

arch/s390/kvm/kvm-s390.c

+3 −0
Original line number Diff line number Diff line
@@ -1068,6 +1068,9 @@ static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu) 
		goto retry;

	}



	/* nothing to do, just clear the request */

	clear_bit(KVM_REQ_UNHALT, &vcpu->requests);



	return 0;

}