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, 4 insertions, 1 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 54ea39f96ecd..a27d0d5a6f86 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -13,6 +13,8 @@
 
 #ifndef ASM_KVM_HOST_H
 #define ASM_KVM_HOST_H
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
 #include <linux/kvm_host.h>
 #include <asm/debug.h>
 #include <asm/cpuid.h>
@@ -210,7 +212,8 @@ struct kvm_vcpu_arch {
         s390_fp_regs      guest_fpregs;
         unsigned int      guest_acrs[NUM_ACRS];
         struct kvm_s390_local_interrupt local_int;
-        struct timer_list ckc_timer;
+        struct hrtimer    ckc_timer;
+        struct tasklet_struct tasklet;
         union  {
                 cpuid_t   cpu_id;
                 u64       stidp_data;