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Commit 544c6761 authored by Alexander Graf's avatar Alexander Graf Committed by Benjamin Herrenschmidt
Browse files

Use hrtimers for the decrementer 



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: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent c8240bd6

arch/powerpc/include/asm/kvm_host.h

+4 −2
Original line number Diff line number Diff line
@@ -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;

arch/powerpc/kvm/emulate.c

+11 −7
Original line number Diff line number Diff line
@@ -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);

	}

}

arch/powerpc/kvm/powerpc.c

+18 −2
Original line number Diff line number Diff line
@@ -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;

}