From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Carsten Otte <cotte@xxxxxxxxxx>
---
include/asm/kvm_host.h | 5 ++++-
kvm/interrupt.c | 35 +++++++++++++++++++++++++----------
kvm/kvm-s390.c | 7 +++++--
kvm/kvm-s390.h | 4 +++-
4 files changed, 37 insertions(+), 14 deletions(-)
Index: kvm/arch/s390/include/asm/kvm_host.h
===================================================================
--- kvm.orig/arch/s390/include/asm/kvm_host.h 2009-05-05 15:58:45.000000000 +0200
+++ kvm/arch/s390/include/asm/kvm_host.h 2009-05-05 16:16:49.000000000 +0200
@@ -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 @@
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;
Index: kvm/arch/s390/kvm/interrupt.c
===================================================================
--- kvm.orig/arch/s390/kvm/interrupt.c 2009-05-05 15:58:45.000000000 +0200
+++ kvm/arch/s390/kvm/interrupt.c 2009-05-05 16:18:02.000000000 +0200
@@ -12,6 +12,8 @@
#include <asm/lowcore.h>
#include <asm/uaccess.h>
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
#include <linux/kvm_host.h>
#include <linux/signal.h>
#include "kvm-s390.h"
@@ -361,12 +363,12 @@
return 0;
}
- sltime = (vcpu->arch.sie_block->ckc - now) / (0xf4240000ul / HZ) + 1;
+ sltime = (vcpu->arch.sie_block->ckc - now)/4096*1000;
- vcpu->arch.ckc_timer.expires = jiffies + sltime;
-
- add_timer(&vcpu->arch.ckc_timer);
- VCPU_EVENT(vcpu, 5, "enabled wait timer:%llx jiffies", sltime);
+ 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:
spin_lock_bh(&vcpu->arch.local_int.float_int->lock);
spin_lock_bh(&vcpu->arch.local_int.lock);
@@ -389,21 +391,34 @@
remove_wait_queue(&vcpu->wq, &wait);
spin_unlock_bh(&vcpu->arch.local_int.lock);
spin_unlock_bh(&vcpu->arch.local_int.float_int->lock);
- del_timer(&vcpu->arch.ckc_timer);
+ hrtimer_try_to_cancel(&vcpu->arch.ckc_timer);
return 0;
}
-void kvm_s390_idle_wakeup(unsigned long data)
+void kvm_s390_tasklet(unsigned long parm)
{
- struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
+ struct kvm_vcpu *vcpu = (struct kvm_vcpu *) parm;
- spin_lock_bh(&vcpu->arch.local_int.lock);
+ spin_lock(&vcpu->arch.local_int.lock);
vcpu->arch.local_int.timer_due = 1;
if (waitqueue_active(&vcpu->arch.local_int.wq))
wake_up_interruptible(&vcpu->arch.local_int.wq);
- spin_unlock_bh(&vcpu->arch.local_int.lock);
+ spin_unlock(&vcpu->arch.local_int.lock);
}
+/*
+ * low level hrtimer wake routine. Because this runs in hardirq context
+ * we schedule a tasklet to do the real work.
+ */
+enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer)
+{
+ struct kvm_vcpu *vcpu;
+
+ vcpu = container_of(timer, struct kvm_vcpu, arch.ckc_timer);
+ tasklet_schedule(&vcpu->arch.tasklet);
+
+ return HRTIMER_NORESTART;
+}
void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
{
Index: kvm/arch/s390/kvm/kvm-s390.c
===================================================================
--- kvm.orig/arch/s390/kvm/kvm-s390.c 2009-05-05 16:16:48.000000000 +0200
+++ kvm/arch/s390/kvm/kvm-s390.c 2009-05-05 16:16:49.000000000 +0200
@@ -15,6 +15,7 @@
#include <linux/compiler.h>
#include <linux/err.h>
#include <linux/fs.h>
+#include <linux/hrtimer.h>
#include <linux/init.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
@@ -286,8 +287,10 @@
vcpu->arch.sie_block->gmsor = vcpu->kvm->arch.guest_origin;
vcpu->arch.sie_block->ecb = 2;
vcpu->arch.sie_block->eca = 0xC1002001U;
- setup_timer(&vcpu->arch.ckc_timer, kvm_s390_idle_wakeup,
- (unsigned long) vcpu);
+ hrtimer_init(&vcpu->arch.ckc_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+ tasklet_init(&vcpu->arch.tasklet, kvm_s390_tasklet,
+ (unsigned long) vcpu);
+ vcpu->arch.ckc_timer.function = kvm_s390_idle_wakeup;
get_cpu_id(&vcpu->arch.cpu_id);
vcpu->arch.cpu_id.version = 0xff;
return 0;
Index: kvm/arch/s390/kvm/kvm-s390.h
===================================================================
--- kvm.orig/arch/s390/kvm/kvm-s390.h 2009-05-05 15:58:45.000000000 +0200
+++ kvm/arch/s390/kvm/kvm-s390.h 2009-05-05 16:16:49.000000000 +0200
@@ -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 @@
}
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);
--
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