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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>
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2668dab794
commit
ca8723023f
4 changed files with 35 additions and 14 deletions
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@ -13,6 +13,8 @@
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#ifndef ASM_KVM_HOST_H
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#define ASM_KVM_HOST_H
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/kvm_host.h>
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#include <asm/debug.h>
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#include <asm/cpuid.h>
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@ -210,7 +212,8 @@ struct kvm_vcpu_arch {
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s390_fp_regs guest_fpregs;
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unsigned int guest_acrs[NUM_ACRS];
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struct kvm_s390_local_interrupt local_int;
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struct timer_list ckc_timer;
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struct hrtimer ckc_timer;
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struct tasklet_struct tasklet;
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union {
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cpuid_t cpu_id;
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u64 stidp_data;
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@ -12,6 +12,8 @@
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#include <asm/lowcore.h>
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#include <asm/uaccess.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/kvm_host.h>
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#include <linux/signal.h>
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#include "kvm-s390.h"
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@ -361,12 +363,10 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
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return 0;
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}
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sltime = (vcpu->arch.sie_block->ckc - now) / (0xf4240000ul / HZ) + 1;
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sltime = ((vcpu->arch.sie_block->ckc - now)*125)>>9;
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vcpu->arch.ckc_timer.expires = jiffies + sltime;
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add_timer(&vcpu->arch.ckc_timer);
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VCPU_EVENT(vcpu, 5, "enabled wait timer:%llx jiffies", sltime);
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hrtimer_start(&vcpu->arch.ckc_timer, ktime_set (0, sltime) , HRTIMER_MODE_REL);
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VCPU_EVENT(vcpu, 5, "enabled wait via clock comparator: %llx ns", sltime);
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no_timer:
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spin_lock_bh(&vcpu->arch.local_int.float_int->lock);
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spin_lock_bh(&vcpu->arch.local_int.lock);
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@ -389,21 +389,34 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
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remove_wait_queue(&vcpu->wq, &wait);
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spin_unlock_bh(&vcpu->arch.local_int.lock);
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spin_unlock_bh(&vcpu->arch.local_int.float_int->lock);
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del_timer(&vcpu->arch.ckc_timer);
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hrtimer_try_to_cancel(&vcpu->arch.ckc_timer);
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return 0;
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}
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void kvm_s390_idle_wakeup(unsigned long data)
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void kvm_s390_tasklet(unsigned long parm)
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{
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struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
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struct kvm_vcpu *vcpu = (struct kvm_vcpu *) parm;
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spin_lock_bh(&vcpu->arch.local_int.lock);
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spin_lock(&vcpu->arch.local_int.lock);
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vcpu->arch.local_int.timer_due = 1;
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if (waitqueue_active(&vcpu->arch.local_int.wq))
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wake_up_interruptible(&vcpu->arch.local_int.wq);
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spin_unlock_bh(&vcpu->arch.local_int.lock);
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spin_unlock(&vcpu->arch.local_int.lock);
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}
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/*
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* low level hrtimer wake routine. Because this runs in hardirq context
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* we schedule a tasklet to do the real work.
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*/
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enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer)
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{
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struct kvm_vcpu *vcpu;
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vcpu = container_of(timer, struct kvm_vcpu, arch.ckc_timer);
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tasklet_schedule(&vcpu->arch.tasklet);
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return HRTIMER_NORESTART;
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}
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void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
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{
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@ -15,6 +15,7 @@
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#include <linux/compiler.h>
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#include <linux/err.h>
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#include <linux/fs.h>
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#include <linux/hrtimer.h>
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#include <linux/init.h>
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#include <linux/kvm.h>
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#include <linux/kvm_host.h>
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@ -283,8 +284,10 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
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vcpu->arch.sie_block->gmsor = vcpu->kvm->arch.guest_origin;
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vcpu->arch.sie_block->ecb = 2;
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vcpu->arch.sie_block->eca = 0xC1002001U;
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setup_timer(&vcpu->arch.ckc_timer, kvm_s390_idle_wakeup,
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(unsigned long) vcpu);
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hrtimer_init(&vcpu->arch.ckc_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
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tasklet_init(&vcpu->arch.tasklet, kvm_s390_tasklet,
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(unsigned long) vcpu);
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vcpu->arch.ckc_timer.function = kvm_s390_idle_wakeup;
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get_cpu_id(&vcpu->arch.cpu_id);
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vcpu->arch.cpu_id.version = 0xff;
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return 0;
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@ -14,6 +14,7 @@
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#ifndef ARCH_S390_KVM_S390_H
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#define ARCH_S390_KVM_S390_H
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#include <linux/hrtimer.h>
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#include <linux/kvm.h>
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#include <linux/kvm_host.h>
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@ -41,7 +42,8 @@ static inline int __cpu_is_stopped(struct kvm_vcpu *vcpu)
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}
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int kvm_s390_handle_wait(struct kvm_vcpu *vcpu);
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void kvm_s390_idle_wakeup(unsigned long data);
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enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer);
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void kvm_s390_tasklet(unsigned long parm);
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void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu);
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int kvm_s390_inject_vm(struct kvm *kvm,
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struct kvm_s390_interrupt *s390int);
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