diff mbox

[V3] ARM: KVM: Allow host virtual timer irq number to be different from guest virtual timer irq number

Message ID 1366982847-11028-1-git-send-email-anup.patel@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Anup Patel April 26, 2013, 1:27 p.m. UTC
The arch_timer irq numbers (or PPI number) are implementation dependent so, the host virtual timer irq number can be different from guest virtual timer irq number.

This patch ensures that host virtual timer irq number is read from DTB and guest virtual timer irq is determined based on guest vcpu target type.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 arch/arm/include/asm/kvm_arch_timer.h |    7 +++++++
 arch/arm/include/asm/kvm_host.h       |    1 +
 arch/arm/kvm/arch_timer.c             |   32 +++++++++++++++++++++++++-------
 arch/arm/kvm/guest.c                  |   15 +++++++++++++++
 arch/arm/kvm/reset.c                  |    4 +++-
 5 files changed, 51 insertions(+), 8 deletions(-)

Comments

Marc Zyngier April 26, 2013, 1:47 p.m. UTC | #1
On 26/04/13 14:27, Anup Patel wrote:
> The arch_timer irq numbers (or PPI number) are implementation dependent so, the host virtual timer irq number can be different from guest virtual timer irq number.
> 
> This patch ensures that host virtual timer irq number is read from DTB and guest virtual timer irq is determined based on guest vcpu target type.
> 
> Signed-off-by: Anup Patel <anup.patel@linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> ---
>  arch/arm/include/asm/kvm_arch_timer.h |    7 +++++++
>  arch/arm/include/asm/kvm_host.h       |    1 +
>  arch/arm/kvm/arch_timer.c             |   32 +++++++++++++++++++++++++-------
>  arch/arm/kvm/guest.c                  |   15 +++++++++++++++
>  arch/arm/kvm/reset.c                  |    4 +++-
>  5 files changed, 51 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_arch_timer.h b/arch/arm/include/asm/kvm_arch_timer.h
> index 68cb9e1..c5c135b 100644
> --- a/arch/arm/include/asm/kvm_arch_timer.h
> +++ b/arch/arm/include/asm/kvm_arch_timer.h
> @@ -61,6 +61,7 @@ struct arch_timer_cpu {
>  #ifdef CONFIG_KVM_ARM_TIMER
>  int kvm_timer_hyp_init(void);
>  int kvm_timer_init(struct kvm *kvm);
> +int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu);
>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
>  void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
>  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
> @@ -76,7 +77,13 @@ static inline int kvm_timer_init(struct kvm *kvm)
>  	return 0;
>  }
>  
> +static int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
> +{
> +	return 0;
> +}
> +
>  static inline void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) {}
> +
>  static inline void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) {}
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 57cb786..cdc0551 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -43,6 +43,7 @@
>  struct kvm_vcpu;
>  u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
>  int kvm_target_cpu(void);
> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu);
>  int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
>  void kvm_reset_coprocs(struct kvm_vcpu *vcpu);
>  
> diff --git a/arch/arm/kvm/arch_timer.c b/arch/arm/kvm/arch_timer.c
> index 49a7516..e558115 100644
> --- a/arch/arm/kvm/arch_timer.c
> +++ b/arch/arm/kvm/arch_timer.c
> @@ -30,7 +30,7 @@
>  
>  static struct timecounter *timecounter;
>  static struct workqueue_struct *wqueue;
> -static struct kvm_irq_level timer_irq = {
> +static struct kvm_irq_level host_timer_irq = {
>  	.level	= 1,
>  };
>  
> @@ -67,8 +67,8 @@ static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
>  
>  	timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
>  	kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
> -			    vcpu->arch.timer_cpu.irq->irq,
> -			    vcpu->arch.timer_cpu.irq->level);
> +			    timer->irq->irq,
> +			    timer->irq->level);
>  }
>  
>  static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
> @@ -156,6 +156,24 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>  	timer_arm(timer, ns);
>  }
>  
> +int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)

If you change this function to:
int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu, struct kvm_irq_level *irq)

...

> +{
> +	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +
> +	/*
> +	 * The vcpu timer irq number cannot be determined in 
> +	 * kvm_timer_vcpu_init() because it is called much before
> +	 * kvm_vcpu_set_target(). To handle this, we determine
> +	 * vcpu timer irq number when the vcpu is resetted.
> +	 */
> +	timer->irq = kvm_target_timer_irq(vcpu);
> +	if (!timer->irq) {
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>  {
>  	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> @@ -163,12 +181,12 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>  	INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
>  	hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
>  	timer->timer.function = kvm_timer_expire;
> -	timer->irq = &timer_irq;
> +	timer->irq = NULL;
>  }
>  
>  static void kvm_timer_init_interrupt(void *info)
>  {
> -	enable_percpu_irq(timer_irq.irq, 0);
> +	enable_percpu_irq(host_timer_irq.irq, 0);
>  }
>  
>  
> @@ -182,7 +200,7 @@ static int kvm_timer_cpu_notify(struct notifier_block *self,
>  		break;
>  	case CPU_DYING:
>  	case CPU_DYING_FROZEN:
> -		disable_percpu_irq(timer_irq.irq);
> +		disable_percpu_irq(host_timer_irq.irq);
>  		break;
>  	}
>  
> @@ -230,7 +248,7 @@ int kvm_timer_hyp_init(void)
>  		goto out;
>  	}
>  
> -	timer_irq.irq = ppi;
> +	host_timer_irq.irq = ppi;
>  
>  	err = register_cpu_notifier(&kvm_timer_cpu_nb);
>  	if (err) {
> diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
> index 152d036..6fbc988 100644
> --- a/arch/arm/kvm/guest.c
> +++ b/arch/arm/kvm/guest.c
> @@ -36,6 +36,11 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
>  	{ NULL }
>  };
>  
> +static struct kvm_irq_level target_cortex_a15_timer_irq = {
> +	.irq = 27,
> +	.level = 1,
> +};

... Move this to reset.c ...

>  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>  {
>  	return 0;
> @@ -197,6 +202,16 @@ int __attribute_const__ kvm_target_cpu(void)
>  	}
>  }
>  
> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu)
> +{
> +	switch (vcpu->arch.target) {
> +	case KVM_ARM_TARGET_CORTEX_A15:
> +		return &target_cortex_a15_timer_irq;
> +	default:
> +		return NULL;
> +	};
> +}

... drop this ...

>  int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
>  			const struct kvm_vcpu_init *init)
>  {
> diff --git a/arch/arm/kvm/reset.c b/arch/arm/kvm/reset.c
> index b80256b..655e567 100644
> --- a/arch/arm/kvm/reset.c
> +++ b/arch/arm/kvm/reset.c
> @@ -26,6 +26,7 @@
>  #include <asm/cputype.h>
>  #include <asm/kvm_arm.h>
>  #include <asm/kvm_coproc.h>
> +#include <asm/kvm_arch_timer.h>
>  
>  /******************************************************************************
>   * Cortex-A15 Reset Values
> @@ -70,5 +71,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)

...

In	case KVM_ARM_TARGET_CORTEX_A15:
[...]
	timer_irq = &target_cortex_a15_timer_irq;

...

>  	/* Reset CP15 registers */
>  	kvm_reset_coprocs(vcpu);
>  
> -	return 0;
> +	/* Reset arch_timer context */
> +	return kvm_timer_vcpu_reset(vcpu);

... and call kvm_timer_vcpu_reset(vcpu, timer_irq)

it would look much better.

	M.
Anup Patel April 26, 2013, 2:48 p.m. UTC | #2
On Fri, Apr 26, 2013 at 7:17 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 26/04/13 14:27, Anup Patel wrote:
>> The arch_timer irq numbers (or PPI number) are implementation dependent so, the host virtual timer irq number can be different from guest virtual timer irq number.
>>
>> This patch ensures that host virtual timer irq number is read from DTB and guest virtual timer irq is determined based on guest vcpu target type.
>>
>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
>> ---
>>  arch/arm/include/asm/kvm_arch_timer.h |    7 +++++++
>>  arch/arm/include/asm/kvm_host.h       |    1 +
>>  arch/arm/kvm/arch_timer.c             |   32 +++++++++++++++++++++++++-------
>>  arch/arm/kvm/guest.c                  |   15 +++++++++++++++
>>  arch/arm/kvm/reset.c                  |    4 +++-
>>  5 files changed, 51 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_arch_timer.h b/arch/arm/include/asm/kvm_arch_timer.h
>> index 68cb9e1..c5c135b 100644
>> --- a/arch/arm/include/asm/kvm_arch_timer.h
>> +++ b/arch/arm/include/asm/kvm_arch_timer.h
>> @@ -61,6 +61,7 @@ struct arch_timer_cpu {
>>  #ifdef CONFIG_KVM_ARM_TIMER
>>  int kvm_timer_hyp_init(void);
>>  int kvm_timer_init(struct kvm *kvm);
>> +int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu);
>>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
>>  void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
>>  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
>> @@ -76,7 +77,13 @@ static inline int kvm_timer_init(struct kvm *kvm)
>>       return 0;
>>  }
>>
>> +static int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
>> +{
>> +     return 0;
>> +}
>> +
>>  static inline void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) {}
>> +
>>  static inline void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) {}
>>  static inline void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) {}
>>  static inline void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) {}
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index 57cb786..cdc0551 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -43,6 +43,7 @@
>>  struct kvm_vcpu;
>>  u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
>>  int kvm_target_cpu(void);
>> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu);
>>  int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
>>  void kvm_reset_coprocs(struct kvm_vcpu *vcpu);
>>
>> diff --git a/arch/arm/kvm/arch_timer.c b/arch/arm/kvm/arch_timer.c
>> index 49a7516..e558115 100644
>> --- a/arch/arm/kvm/arch_timer.c
>> +++ b/arch/arm/kvm/arch_timer.c
>> @@ -30,7 +30,7 @@
>>
>>  static struct timecounter *timecounter;
>>  static struct workqueue_struct *wqueue;
>> -static struct kvm_irq_level timer_irq = {
>> +static struct kvm_irq_level host_timer_irq = {
>>       .level  = 1,
>>  };
>>
>> @@ -67,8 +67,8 @@ static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
>>
>>       timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
>>       kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
>> -                         vcpu->arch.timer_cpu.irq->irq,
>> -                         vcpu->arch.timer_cpu.irq->level);
>> +                         timer->irq->irq,
>> +                         timer->irq->level);
>>  }
>>
>>  static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
>> @@ -156,6 +156,24 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>>       timer_arm(timer, ns);
>>  }
>>
>> +int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
>
> If you change this function to:
> int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu, struct kvm_irq_level *irq)
>
> ...
>
>> +{
>> +     struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
>> +
>> +     /*
>> +      * The vcpu timer irq number cannot be determined in
>> +      * kvm_timer_vcpu_init() because it is called much before
>> +      * kvm_vcpu_set_target(). To handle this, we determine
>> +      * vcpu timer irq number when the vcpu is resetted.
>> +      */
>> +     timer->irq = kvm_target_timer_irq(vcpu);
>> +     if (!timer->irq) {
>> +             return -ENODEV;
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>>  {
>>       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
>> @@ -163,12 +181,12 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>>       INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
>>       hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
>>       timer->timer.function = kvm_timer_expire;
>> -     timer->irq = &timer_irq;
>> +     timer->irq = NULL;
>>  }
>>
>>  static void kvm_timer_init_interrupt(void *info)
>>  {
>> -     enable_percpu_irq(timer_irq.irq, 0);
>> +     enable_percpu_irq(host_timer_irq.irq, 0);
>>  }
>>
>>
>> @@ -182,7 +200,7 @@ static int kvm_timer_cpu_notify(struct notifier_block *self,
>>               break;
>>       case CPU_DYING:
>>       case CPU_DYING_FROZEN:
>> -             disable_percpu_irq(timer_irq.irq);
>> +             disable_percpu_irq(host_timer_irq.irq);
>>               break;
>>       }
>>
>> @@ -230,7 +248,7 @@ int kvm_timer_hyp_init(void)
>>               goto out;
>>       }
>>
>> -     timer_irq.irq = ppi;
>> +     host_timer_irq.irq = ppi;
>>
>>       err = register_cpu_notifier(&kvm_timer_cpu_nb);
>>       if (err) {
>> diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
>> index 152d036..6fbc988 100644
>> --- a/arch/arm/kvm/guest.c
>> +++ b/arch/arm/kvm/guest.c
>> @@ -36,6 +36,11 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
>>       { NULL }
>>  };
>>
>> +static struct kvm_irq_level target_cortex_a15_timer_irq = {
>> +     .irq = 27,
>> +     .level = 1,
>> +};
>
> ... Move this to reset.c ...
>
>>  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>>  {
>>       return 0;
>> @@ -197,6 +202,16 @@ int __attribute_const__ kvm_target_cpu(void)
>>       }
>>  }
>>
>> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu)
>> +{
>> +     switch (vcpu->arch.target) {
>> +     case KVM_ARM_TARGET_CORTEX_A15:
>> +             return &target_cortex_a15_timer_irq;
>> +     default:
>> +             return NULL;
>> +     };
>> +}
>
> ... drop this ...
>
>>  int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
>>                       const struct kvm_vcpu_init *init)
>>  {
>> diff --git a/arch/arm/kvm/reset.c b/arch/arm/kvm/reset.c
>> index b80256b..655e567 100644
>> --- a/arch/arm/kvm/reset.c
>> +++ b/arch/arm/kvm/reset.c
>> @@ -26,6 +26,7 @@
>>  #include <asm/cputype.h>
>>  #include <asm/kvm_arm.h>
>>  #include <asm/kvm_coproc.h>
>> +#include <asm/kvm_arch_timer.h>
>>
>>  /******************************************************************************
>>   * Cortex-A15 Reset Values
>> @@ -70,5 +71,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>
> ...
>
> In      case KVM_ARM_TARGET_CORTEX_A15:
> [...]
>         timer_irq = &target_cortex_a15_timer_irq;
>
> ...
>
>>       /* Reset CP15 registers */
>>       kvm_reset_coprocs(vcpu);
>>
>> -     return 0;
>> +     /* Reset arch_timer context */
>> +     return kvm_timer_vcpu_reset(vcpu);
>
> ... and call kvm_timer_vcpu_reset(vcpu, timer_irq)
>
> it would look much better.
>
>         M.
> --
> Jazz is not dead. It just smells funny...
>
>
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm

Sure, I incorporate all above comments and send revised patch.

Regards,
Anup
Christoffer Dall April 26, 2013, 6:27 p.m. UTC | #3
>
> Sure, I incorporate all above comments and send revised patch.
>
Hi Anup,

Now when we're at it, your commit message is exessively long, both the
title and the actual content. Please try to keep the commit message
under 80 chars at least and the title of the patch even shorter if
possible: think doing a 'git log' on an 80 char terminal...

-Christoffer
Anup Patel April 26, 2013, 7:11 p.m. UTC | #4
On Fri, Apr 26, 2013 at 11:57 PM, Christoffer Dall
<cdall@cs.columbia.edu> wrote:
>>
>> Sure, I incorporate all above comments and send revised patch.
>>
> Hi Anup,
>
> Now when we're at it, your commit message is exessively long, both the
> title and the actual content. Please try to keep the commit message
> under 80 chars at least and the title of the patch even shorter if
> possible: think doing a 'git log' on an 80 char terminal...
>
> -Christoffer

Oke, I'll keep the commit message shorter.

-Anup
Christoffer Dall April 26, 2013, 8:39 p.m. UTC | #5
On Fri, Apr 26, 2013 at 12:11 PM, Anup Patel <anup@brainfault.org> wrote:
> On Fri, Apr 26, 2013 at 11:57 PM, Christoffer Dall
> <cdall@cs.columbia.edu> wrote:
>>>
>>> Sure, I incorporate all above comments and send revised patch.
>>>
>> Hi Anup,
>>
>> Now when we're at it, your commit message is exessively long, both the
>> title and the actual content. Please try to keep the commit message
>> under 80 chars at least and the title of the patch even shorter if
>> possible: think doing a 'git log' on an 80 char terminal...
>>
>> -Christoffer
>
> Oke, I'll keep the commit message shorter.
>
thanks, just to be clear, the body of the message can be as long as
appropriate, but the lines should be wrapped at 80 chars max.
diff mbox

Patch

diff --git a/arch/arm/include/asm/kvm_arch_timer.h b/arch/arm/include/asm/kvm_arch_timer.h
index 68cb9e1..c5c135b 100644
--- a/arch/arm/include/asm/kvm_arch_timer.h
+++ b/arch/arm/include/asm/kvm_arch_timer.h
@@ -61,6 +61,7 @@  struct arch_timer_cpu {
 #ifdef CONFIG_KVM_ARM_TIMER
 int kvm_timer_hyp_init(void);
 int kvm_timer_init(struct kvm *kvm);
+int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu);
 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
@@ -76,7 +77,13 @@  static inline int kvm_timer_init(struct kvm *kvm)
 	return 0;
 }
 
+static int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
 static inline void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) {}
+
 static inline void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) {}
 static inline void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) {}
 static inline void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) {}
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 57cb786..cdc0551 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -43,6 +43,7 @@ 
 struct kvm_vcpu;
 u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
 int kvm_target_cpu(void);
+struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu);
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
 void kvm_reset_coprocs(struct kvm_vcpu *vcpu);
 
diff --git a/arch/arm/kvm/arch_timer.c b/arch/arm/kvm/arch_timer.c
index 49a7516..e558115 100644
--- a/arch/arm/kvm/arch_timer.c
+++ b/arch/arm/kvm/arch_timer.c
@@ -30,7 +30,7 @@ 
 
 static struct timecounter *timecounter;
 static struct workqueue_struct *wqueue;
-static struct kvm_irq_level timer_irq = {
+static struct kvm_irq_level host_timer_irq = {
 	.level	= 1,
 };
 
@@ -67,8 +67,8 @@  static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
 
 	timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
 	kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
-			    vcpu->arch.timer_cpu.irq->irq,
-			    vcpu->arch.timer_cpu.irq->level);
+			    timer->irq->irq,
+			    timer->irq->level);
 }
 
 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
@@ -156,6 +156,24 @@  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 	timer_arm(timer, ns);
 }
 
+int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	/*
+	 * The vcpu timer irq number cannot be determined in 
+	 * kvm_timer_vcpu_init() because it is called much before
+	 * kvm_vcpu_set_target(). To handle this, we determine
+	 * vcpu timer irq number when the vcpu is resetted.
+	 */
+	timer->irq = kvm_target_timer_irq(vcpu);
+	if (!timer->irq) {
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
@@ -163,12 +181,12 @@  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 	INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 	hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 	timer->timer.function = kvm_timer_expire;
-	timer->irq = &timer_irq;
+	timer->irq = NULL;
 }
 
 static void kvm_timer_init_interrupt(void *info)
 {
-	enable_percpu_irq(timer_irq.irq, 0);
+	enable_percpu_irq(host_timer_irq.irq, 0);
 }
 
 
@@ -182,7 +200,7 @@  static int kvm_timer_cpu_notify(struct notifier_block *self,
 		break;
 	case CPU_DYING:
 	case CPU_DYING_FROZEN:
-		disable_percpu_irq(timer_irq.irq);
+		disable_percpu_irq(host_timer_irq.irq);
 		break;
 	}
 
@@ -230,7 +248,7 @@  int kvm_timer_hyp_init(void)
 		goto out;
 	}
 
-	timer_irq.irq = ppi;
+	host_timer_irq.irq = ppi;
 
 	err = register_cpu_notifier(&kvm_timer_cpu_nb);
 	if (err) {
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index 152d036..6fbc988 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -36,6 +36,11 @@  struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ NULL }
 };
 
+static struct kvm_irq_level target_cortex_a15_timer_irq = {
+	.irq = 27,
+	.level = 1,
+};
+
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 {
 	return 0;
@@ -197,6 +202,16 @@  int __attribute_const__ kvm_target_cpu(void)
 	}
 }
 
+struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu)
+{
+	switch (vcpu->arch.target) {
+	case KVM_ARM_TARGET_CORTEX_A15:
+		return &target_cortex_a15_timer_irq;
+	default:
+		return NULL;
+	};
+}
+
 int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 			const struct kvm_vcpu_init *init)
 {
diff --git a/arch/arm/kvm/reset.c b/arch/arm/kvm/reset.c
index b80256b..655e567 100644
--- a/arch/arm/kvm/reset.c
+++ b/arch/arm/kvm/reset.c
@@ -26,6 +26,7 @@ 
 #include <asm/cputype.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_coproc.h>
+#include <asm/kvm_arch_timer.h>
 
 /******************************************************************************
  * Cortex-A15 Reset Values
@@ -70,5 +71,6 @@  int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	/* Reset CP15 registers */
 	kvm_reset_coprocs(vcpu);
 
-	return 0;
+	/* Reset arch_timer context */
+	return kvm_timer_vcpu_reset(vcpu);
 }