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: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

3 files changed, 8 insertions, 37 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index c2ba0208a0e1..b3acf28c8c96 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -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;
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 90c8de22a2a0..5fd11ce3dc3d 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -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);
 }
 
 /*
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index fdf88f7a539c..ecb135702313 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1068,6 +1068,9 @@ retry:
                 goto retry;
         }
 
+        /* nothing to do, just clear the request */
+        clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
+
         return 0;
 }