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Use hrtimers for the decrementer

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Following S390's good example we should use hrtimers for the decrementer too!
This patch converts the timer from the old mechanism to hrtimers.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Alexander Graf 2009-11-02 12:02:31 +00:00 committed by Benjamin Herrenschmidt
parent c8240bd6f0
commit 544c6761bb
3 changed files with 33 additions and 11 deletions
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6
arch/powerpc/include/asm/kvm_host.h
View File

@ -21,7 +21,8 @@
#define __POWERPC_KVM_HOST_H__
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/types.h>
#include <linux/kvm_types.h>
#include <asm/kvm_asm.h>
@ -250,7 +251,8 @@ struct kvm_vcpu_arch {
u32 cpr0_cfgaddr; /* holds the last set cpr0_cfgaddr */
struct timer_list dec_timer;
struct hrtimer dec_timer;
struct tasklet_struct tasklet;
u64 dec_jiffies;
unsigned long pending_exceptions;

18
arch/powerpc/kvm/emulate.c
View File

@ -18,7 +18,7 @@
*/
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/hrtimer.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm_host.h>
@ -79,12 +79,13 @@ static int kvmppc_dec_enabled(struct kvm_vcpu *vcpu)
void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
{
unsigned long nr_jiffies;
unsigned long dec_nsec;
pr_debug("mtDEC: %x\n", vcpu->arch.dec);
#ifdef CONFIG_PPC64
/* POWER4+ triggers a dec interrupt if the value is < 0 */
if (vcpu->arch.dec & 0x80000000) {
del_timer(&vcpu->arch.dec_timer);
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
kvmppc_core_queue_dec(vcpu);
return;
}
@ -94,12 +95,15 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
* that's how we convert the guest DEC value to the number of
* host ticks. */
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
dec_nsec = vcpu->arch.dec;
dec_nsec *= 1000;
dec_nsec /= tb_ticks_per_usec;
hrtimer_start(&vcpu->arch.dec_timer, ktime_set(0, dec_nsec),
HRTIMER_MODE_REL);
vcpu->arch.dec_jiffies = get_tb();
nr_jiffies = vcpu->arch.dec / tb_ticks_per_jiffy;
mod_timer(&vcpu->arch.dec_timer,
get_jiffies_64() + nr_jiffies);
} else {
del_timer(&vcpu->arch.dec_timer);
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
}
}

20
arch/powerpc/kvm/powerpc.c
View File

@ -23,6 +23,7 @@
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/hrtimer.h>
#include <linux/fs.h>
#include <asm/cputable.h>
#include <asm/uaccess.h>
@ -208,10 +209,25 @@ static void kvmppc_decrementer_func(unsigned long data)
}
}
/*
* low level hrtimer wake routine. Because this runs in hardirq context
* we schedule a tasklet to do the real work.
*/
enum hrtimer_restart kvmppc_decrementer_wakeup(struct hrtimer *timer)
{
struct kvm_vcpu *vcpu;
vcpu = container_of(timer, struct kvm_vcpu, arch.dec_timer);
tasklet_schedule(&vcpu->arch.tasklet);
return HRTIMER_NORESTART;
}
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
setup_timer(&vcpu->arch.dec_timer, kvmppc_decrementer_func,
(unsigned long)vcpu);
hrtimer_init(&vcpu->arch.dec_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
tasklet_init(&vcpu->arch.tasklet, kvmppc_decrementer_func, (ulong)vcpu);
vcpu->arch.dec_timer.function = kvmppc_decrementer_wakeup;
return 0;
}