[GIT PULL 1/9] KVM: s390: cleanup handle_wait by reusing kvm_vcpu_block

Christian Borntraeger
2014-07-21T19:14:17Z

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

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>
---
arch/s390/include/asm/kvm_host.h | 1 -
arch/s390/kvm/interrupt.c | 41 +++++-----------------------------------
arch/s390/kvm/kvm-s390.c | 3 +++
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 c2ba020..b3acf28 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 90c8de2..5fd11ce 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 fdf88f7..ecb1357 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;
}

--
1.8.4.2