KVM: s390: use hrtimer for clock wakeup from idle - v2

This patch reworks the s390 clock comparator wakeup to hrtimer. The clock
comparator is a per-cpu value that is compared against the TOD clock. If
ckc <= TOD an external interrupt 1004 is triggered. Since the clock comparator
and the TOD clock have a much higher resolution than jiffies we should use
hrtimers to trigger the wakeup. This speeds up guest nanosleep for small
values.

Since hrtimers callbacks run in hard-irq context, I added a tasklet to do
the actual work with enabled interrupts.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Ehrhardt <ehrhardt@de.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 00bbe69b78da..748fee872323 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -14,6 +14,7 @@
 #ifndef ARCH_S390_KVM_S390_H
 #define ARCH_S390_KVM_S390_H
 
+#include <linux/hrtimer.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 
@@ -41,7 +42,8 @@ static inline int __cpu_is_stopped(struct kvm_vcpu *vcpu)
 }
 
 int kvm_s390_handle_wait(struct kvm_vcpu *vcpu);
-void kvm_s390_idle_wakeup(unsigned long data);
+enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer);
+void kvm_s390_tasklet(unsigned long parm);
 void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu);
 int kvm_s390_inject_vm(struct kvm *kvm,
                 struct kvm_s390_interrupt *s390int);