[PATCH 0/2] irq routing userspace

[PATCH 0/2] irq routing userspace

[Avi Kivity]

Following is the userspace support for irq routing.  It is also available
(along with a slightly fixed kernel patch) in the irq-routing-2 branch
on kernel.org.

Avi Kivity (2):
  kvm: libkvm: support for irq routing
  kvm: qemu: initialize irq routing table

 libkvm/kvm-common.h |    4 ++
 libkvm/libkvm.c     |  107 +++++++++++++++++++++++++++++++++++++++++++++++++++
 libkvm/libkvm.h     |   62 +++++++++++++++++++++++++++++
 qemu/qemu-kvm.c     |   24 +++++++++++
 4 files changed, 197 insertions(+), 0 deletions(-)

[PATCH 1/2] kvm: libkvm: support for irq routing

[Avi Kivity]

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 libkvm/kvm-common.h |    4 ++
 libkvm/libkvm.c     |  107 +++++++++++++++++++++++++++++++++++++++++++++++++++
 libkvm/libkvm.h     |   62 +++++++++++++++++++++++++++++
 3 files changed, 173 insertions(+), 0 deletions(-)

diff --git a/libkvm/kvm-common.h b/libkvm/kvm-common.h
index c5beacc..e09c07c 100644
--- a/libkvm/kvm-common.h
+++ b/libkvm/kvm-common.h
@@ -61,6 +61,10 @@ struct kvm_context {
 	int pit_in_kernel;
 	/// in-kernel coalesced mmio
 	int coalesced_mmio;
+#ifdef KVM_CAP_IRQ_ROUTING
+	struct kvm_irq_routing *irq_routes;
+	int nr_allocated_irq_routes;
+#endif
 };
 
 void init_slots(void);
diff --git a/libkvm/libkvm.c b/libkvm/libkvm.c
index 0408fdb..1004fa6 100644
--- a/libkvm/libkvm.c
+++ b/libkvm/libkvm.c
@@ -381,6 +381,14 @@ int kvm_create_vm(kvm_context_t kvm)
 {
 	int fd = kvm->fd;
 
+#ifdef KVM_CAP_IRQ_ROUTING
+	kvm->irq_routes = malloc(sizeof(*kvm->irq_routes));
+	if (!kvm->irq_routes)
+		return -ENOMEM;
+	memset(kvm->irq_routes, 0, sizeof(*kvm->irq_routes));
+	kvm->nr_allocated_irq_routes = 0;
+#endif
+
 	kvm->vcpu_fd[0] = -1;
 
 	fd = ioctl(fd, KVM_CREATE_VM, 0);
@@ -1164,3 +1172,102 @@ int kvm_reinject_control(kvm_context_t kvm, int pit_reinject)
 #endif
 	return -ENOSYS;
 }
+
+int kvm_has_gsi_routing(kvm_context_t kvm)
+{
+    int r = 0;
+
+#ifdef KVM_CAP_IRQ_ROUTING
+    r = kvm_check_extension(kvm, KVM_CAP_IRQ_ROUTING);
+#endif
+    return r;
+}
+
+int kvm_get_gsi_count(kvm_context_t kvm)
+{
+#ifdef KVM_CAP_IRQ_ROUTING
+	return kvm_check_extension(kvm, KVM_CAP_IRQ_ROUTING);
+#else
+	return -EINVAL;
+#endif
+}
+
+int kvm_clear_gsi_routes(kvm_context_t kvm)
+{
+#ifdef KVM_CAP_IRQ_ROUTING
+	kvm->irq_routes->nr = 0;
+	return 0;
+#else
+	return -EINVAL;
+#endif
+}
+
+int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
+{
+#ifdef KVM_CAP_IRQ_ROUTING
+	struct kvm_irq_routing *z;
+	struct kvm_irq_routing_entry *e;
+	int n, size;
+
+	if (kvm->irq_routes->nr == kvm->nr_allocated_irq_routes) {
+		n = kvm->nr_allocated_irq_routes * 2;
+		if (n < 64)
+			n = 64;
+		size = sizeof(struct kvm_irq_routing);
+		size += n * sizeof(*e);
+		z = realloc(kvm->irq_routes, size);
+		if (!z)
+			return -ENOMEM;
+		kvm->nr_allocated_irq_routes = n;
+		kvm->irq_routes = z;
+	}
+	n = kvm->irq_routes->nr++;
+	e = &kvm->irq_routes->entries[n];
+	memset(e, 0, sizeof(*e));
+	e->gsi = gsi;
+	e->type = KVM_IRQ_ROUTING_IRQCHIP;
+	e->flags = 0;
+	e->u.irqchip.irqchip = irqchip;
+	e->u.irqchip.pin = pin;
+	return 0;
+#else
+	return -ENOSYS;
+#endif
+}
+
+int kvm_del_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
+{
+#ifdef KVM_CAP_IRQ_ROUTING
+	struct kvm_irq_routing_entry *e, *p;
+	int i;
+
+	for (i = 0; i < kvm->irq_routes->nr; ++i) {
+		e = &kvm->irq_routes->entries[i];
+		if (e->type == KVM_IRQ_ROUTING_IRQCHIP
+		    && e->gsi == gsi
+		    && e->u.irqchip.irqchip == irqchip
+		    && e->u.irqchip.pin == pin) {
+			p = &kvm->irq_routes->entries[--kvm->irq_routes->nr];
+			*e = *p;
+			return 0;
+		}
+	}
+	return -ESRCH;
+#else
+	return -ENOSYS;
+#endif
+}
+
+int kvm_commit_irq_routes(kvm_context_t kvm)
+{
+#ifdef KVM_CAP_IRQ_ROUTING
+	int r;
+
+	kvm->irq_routes->flags = 0;
+	r = ioctl(kvm->vm_fd, KVM_SET_GSI_ROUTING, kvm->irq_routes);
+	if (r == -1)
+		r = -errno;
+#else
+	return -ENOSYS;
+#endif
+}
diff --git a/libkvm/libkvm.h b/libkvm/libkvm.h
index ee1ba68..85012ff 100644
--- a/libkvm/libkvm.h
+++ b/libkvm/libkvm.h
@@ -720,4 +720,66 @@ int kvm_assign_irq(kvm_context_t kvm,
  */
 int kvm_destroy_memory_region_works(kvm_context_t kvm);
 #endif
+
+
+/*!
+ * \brief Checks whether the generic irq routing capability is present
+ *
+ * Checks whether kvm can reroute interrupts among the various interrupt
+ * controllers.
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_has_gsi_routing(kvm_context_t kvm);
+
+/*!
+ * \brief Determines the number of gsis that can be routed
+ *
+ * Returns the number of distinct gsis that can be routed by kvm.  This is
+ * also the number of distinct routes (if a gsi has two routes, than another
+ * gsi cannot be used...)
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_get_gsi_count(kvm_context_t kvm);
+
+/*!
+ * \brief Clears the temporary irq routing table
+ *
+ * Clears the temporary irq routing table.  Nothing is committed to the
+ * running VM.
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_clear_gsi_routes(kvm_context_t kvm);
+
+/*!
+ * \brief Adds an irq route to the temporary irq routing table
+ *
+ * Adds an irq route to the temporary irq routing table.  Nothing is
+ * committed to the running VM.
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin);
+
+/*!
+ * \brief Removes an irq route from the temporary irq routing table
+ *
+ * Adds an irq route to the temporary irq routing table.  Nothing is
+ * committed to the running VM.
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_del_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin);
+
+/*!
+ * \brief Commit the temporary irq routing table
+ *
+ * Commit the temporary irq routing table to the running VM.
+ *
+ * \param kvm Pointer to the current kvm_context
+ */
+int kvm_commit_irq_routes(kvm_context_t kvm);
+
 #endif
-- 
1.6.0.6

[PATCH 2/2] kvm: qemu: initialize irq routing table

[Avi Kivity]

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 qemu/qemu-kvm.c |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
index e4fba78..e67b698 100644
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -783,6 +783,8 @@ static int destroy_region_works = 0;
 int kvm_qemu_create_context(void)
 {
     int r;
+    int i;
+
     if (!kvm_irqchip) {
         kvm_disable_irqchip_creation(kvm_context);
     }
@@ -805,6 +807,28 @@ int kvm_qemu_create_context(void)
 #ifdef TARGET_I386
     destroy_region_works = kvm_destroy_memory_region_works(kvm_context);
 #endif
+
+    if (kvm_irqchip && kvm_has_gsi_routing(kvm_context)) {
+        kvm_clear_gsi_routes(kvm_context);
+        for (i = 0; i < 8; ++i) {
+            if (i == 2)
+                continue;
+            r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_PIC_MASTER, i);
+            if (r < 0)
+                return r;
+        }
+        for (i = 8; i < 16; ++i) {
+            r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_PIC_SLAVE, i - 8);
+            if (r < 0)
+                return r;
+        }
+        for (i = 0; i < 24; ++i) {
+            r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_IOAPIC, i);
+            if (r < 0)
+                return r;
+        }
+        kvm_commit_irq_routes(kvm_context);
+    }
     return 0;
 }
 
-- 
1.6.0.6

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Sheng Yang]

On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
> Signed-off-by: Avi Kivity <avi@redhat.com>

Do we need a lock for the table?

-- 
regards
Yang, Sheng

> ---
>  libkvm/kvm-common.h |    4 ++
>  libkvm/libkvm.c     |  107
> +++++++++++++++++++++++++++++++++++++++++++++++++++ libkvm/libkvm.h     |  
> 62 +++++++++++++++++++++++++++++
>  3 files changed, 173 insertions(+), 0 deletions(-)
>
> diff --git a/libkvm/kvm-common.h b/libkvm/kvm-common.h
> index c5beacc..e09c07c 100644
> --- a/libkvm/kvm-common.h
> +++ b/libkvm/kvm-common.h
> @@ -61,6 +61,10 @@ struct kvm_context {
>  	int pit_in_kernel;
>  	/// in-kernel coalesced mmio
>  	int coalesced_mmio;
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	struct kvm_irq_routing *irq_routes;
> +	int nr_allocated_irq_routes;
> +#endif
>  };
>
>  void init_slots(void);
> diff --git a/libkvm/libkvm.c b/libkvm/libkvm.c
> index 0408fdb..1004fa6 100644
> --- a/libkvm/libkvm.c
> +++ b/libkvm/libkvm.c
> @@ -381,6 +381,14 @@ int kvm_create_vm(kvm_context_t kvm)
>  {
>  	int fd = kvm->fd;
>
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	kvm->irq_routes = malloc(sizeof(*kvm->irq_routes));
> +	if (!kvm->irq_routes)
> +		return -ENOMEM;
> +	memset(kvm->irq_routes, 0, sizeof(*kvm->irq_routes));
> +	kvm->nr_allocated_irq_routes = 0;
> +#endif
> +
>  	kvm->vcpu_fd[0] = -1;
>
>  	fd = ioctl(fd, KVM_CREATE_VM, 0);
> @@ -1164,3 +1172,102 @@ int kvm_reinject_control(kvm_context_t kvm, int
> pit_reinject) #endif
>  	return -ENOSYS;
>  }
> +
> +int kvm_has_gsi_routing(kvm_context_t kvm)
> +{
> +    int r = 0;
> +
> +#ifdef KVM_CAP_IRQ_ROUTING
> +    r = kvm_check_extension(kvm, KVM_CAP_IRQ_ROUTING);
> +#endif
> +    return r;
> +}
> +
> +int kvm_get_gsi_count(kvm_context_t kvm)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	return kvm_check_extension(kvm, KVM_CAP_IRQ_ROUTING);
> +#else
> +	return -EINVAL;
> +#endif
> +}
> +
> +int kvm_clear_gsi_routes(kvm_context_t kvm)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	kvm->irq_routes->nr = 0;
> +	return 0;
> +#else
> +	return -EINVAL;
> +#endif
> +}
> +
> +int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	struct kvm_irq_routing *z;
> +	struct kvm_irq_routing_entry *e;
> +	int n, size;
> +
> +	if (kvm->irq_routes->nr == kvm->nr_allocated_irq_routes) {
> +		n = kvm->nr_allocated_irq_routes * 2;
> +		if (n < 64)
> +			n = 64;
> +		size = sizeof(struct kvm_irq_routing);
> +		size += n * sizeof(*e);
> +		z = realloc(kvm->irq_routes, size);
> +		if (!z)
> +			return -ENOMEM;
> +		kvm->nr_allocated_irq_routes = n;
> +		kvm->irq_routes = z;
> +	}
> +	n = kvm->irq_routes->nr++;
> +	e = &kvm->irq_routes->entries[n];
> +	memset(e, 0, sizeof(*e));
> +	e->gsi = gsi;
> +	e->type = KVM_IRQ_ROUTING_IRQCHIP;
> +	e->flags = 0;
> +	e->u.irqchip.irqchip = irqchip;
> +	e->u.irqchip.pin = pin;
> +	return 0;
> +#else
> +	return -ENOSYS;
> +#endif
> +}
> +
> +int kvm_del_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	struct kvm_irq_routing_entry *e, *p;
> +	int i;
> +
> +	for (i = 0; i < kvm->irq_routes->nr; ++i) {
> +		e = &kvm->irq_routes->entries[i];
> +		if (e->type == KVM_IRQ_ROUTING_IRQCHIP
> +		    && e->gsi == gsi
> +		    && e->u.irqchip.irqchip == irqchip
> +		    && e->u.irqchip.pin == pin) {
> +			p = &kvm->irq_routes->entries[--kvm->irq_routes->nr];
> +			*e = *p;
> +			return 0;
> +		}
> +	}
> +	return -ESRCH;
> +#else
> +	return -ENOSYS;
> +#endif
> +}
> +
> +int kvm_commit_irq_routes(kvm_context_t kvm)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +	int r;
> +
> +	kvm->irq_routes->flags = 0;
> +	r = ioctl(kvm->vm_fd, KVM_SET_GSI_ROUTING, kvm->irq_routes);
> +	if (r == -1)
> +		r = -errno;
> +#else
> +	return -ENOSYS;
> +#endif
> +}
> diff --git a/libkvm/libkvm.h b/libkvm/libkvm.h
> index ee1ba68..85012ff 100644
> --- a/libkvm/libkvm.h
> +++ b/libkvm/libkvm.h
> @@ -720,4 +720,66 @@ int kvm_assign_irq(kvm_context_t kvm,
>   */
>  int kvm_destroy_memory_region_works(kvm_context_t kvm);
>  #endif
> +
> +
> +/*!
> + * \brief Checks whether the generic irq routing capability is present
> + *
> + * Checks whether kvm can reroute interrupts among the various interrupt
> + * controllers.
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_has_gsi_routing(kvm_context_t kvm);
> +
> +/*!
> + * \brief Determines the number of gsis that can be routed
> + *
> + * Returns the number of distinct gsis that can be routed by kvm.  This is
> + * also the number of distinct routes (if a gsi has two routes, than
> another + * gsi cannot be used...)
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_get_gsi_count(kvm_context_t kvm);
> +
> +/*!
> + * \brief Clears the temporary irq routing table
> + *
> + * Clears the temporary irq routing table.  Nothing is committed to the
> + * running VM.
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_clear_gsi_routes(kvm_context_t kvm);
> +
> +/*!
> + * \brief Adds an irq route to the temporary irq routing table
> + *
> + * Adds an irq route to the temporary irq routing table.  Nothing is
> + * committed to the running VM.
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin);
> +
> +/*!
> + * \brief Removes an irq route from the temporary irq routing table
> + *
> + * Adds an irq route to the temporary irq routing table.  Nothing is
> + * committed to the running VM.
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_del_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin);
> +
> +/*!
> + * \brief Commit the temporary irq routing table
> + *
> + * Commit the temporary irq routing table to the running VM.
> + *
> + * \param kvm Pointer to the current kvm_context
> + */
> +int kvm_commit_irq_routes(kvm_context_t kvm);
> +
>  #endif

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Sheng Yang]

On Thursday 15 January 2009 14:17:16 Sheng Yang wrote:
> On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
> > Signed-off-by: Avi Kivity <avi@redhat.com>
>
> Do we need a lock for the table?

And kvm_add_irq_route/kvm_del_irq_route should be generic used, how about 
transfer a kvm_irq_routing_entry as parameter?

-- 
regards
Yang, Sheng

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Avi Kivity]

Sheng Yang wrote:
> On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
>   
>> Signed-off-by: Avi Kivity <avi@redhat.com>
>>     
>
> Do we need a lock for the table?
>   

No, that's up to the caller.  libkvm is just a silly wrapper for the ioctls.

In practice, the table will be protected by qemu_mutex.

-- 
error compiling committee.c: too many arguments to function

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Avi Kivity]

Sheng Yang wrote:
> On Thursday 15 January 2009 14:17:16 Sheng Yang wrote:
>   
>> On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
>>     
>>> Signed-off-by: Avi Kivity <avi@redhat.com>
>>>       
>> Do we need a lock for the table?
>>     
>
> And kvm_add_irq_route/kvm_del_irq_route should be generic used, how about 
> transfer a kvm_irq_routing_entry as parameter?
>   

These structures + selectors + unions are clumsy.  For libkvm, I'd 
prefer adding kvm_add_msi() and kvm_del_msi().


-- 
error compiling committee.c: too many arguments to function

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Sheng Yang]

On Thursday 15 January 2009 17:59:43 Avi Kivity wrote:
> Sheng Yang wrote:
> > On Thursday 15 January 2009 14:17:16 Sheng Yang wrote:
> >> On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
> >>> Signed-off-by: Avi Kivity <avi@redhat.com>
> >>
> >> Do we need a lock for the table?
> >
> > And kvm_add_irq_route/kvm_del_irq_route should be generic used, how about
> > transfer a kvm_irq_routing_entry as parameter?
>
> These structures + selectors + unions are clumsy.  For libkvm, I'd
> prefer adding kvm_add_msi() and kvm_del_msi().

But...
> +int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
> +{
> +#ifdef KVM_CAP_IRQ_ROUTING
> +       struct kvm_irq_routing *z;
> +       struct kvm_irq_routing_entry *e;
> +       int n, size;
> +
> +       if (kvm->irq_routes->nr == kvm->nr_allocated_irq_routes) {
> +               n = kvm->nr_allocated_irq_routes * 2;
> +               if (n < 64)
> +                       n = 64;
> +               size = sizeof(struct kvm_irq_routing);
> +               size += n * sizeof(*e);
> +               z = realloc(kvm->irq_routes, size);
> +               if (!z)
> +                       return -ENOMEM;
> +               kvm->nr_allocated_irq_routes = n;
> +               kvm->irq_routes = z;
> +       }
> +       n = kvm->irq_routes->nr++;
> +       e = &kvm->irq_routes->entries[n];
> +       memset(e, 0, sizeof(*e));
> +       e->gsi = gsi;
> +       e->type = KVM_IRQ_ROUTING_IRQCHIP;
> +       e->flags = 0;
> +       e->u.irqchip.irqchip = irqchip;
> +       e->u.irqchip.pin = pin;
> +       return 0;
> +#else
> +       return -ENOSYS;
> +#endif
> +}

Besides three lines, all can be reused... I don't see the reason for another 
function...

And the name here is irq_route, I suppose it should be generic used. Can be 
core function which can be wrapped.

-- 
regards
Yang, Sheng

Re: [PATCH 1/2] kvm: libkvm: support for irq routing

[Avi Kivity]

Sheng Yang wrote:
> On Thursday 15 January 2009 17:59:43 Avi Kivity wrote:
>   
>> Sheng Yang wrote:
>>     
>>> On Thursday 15 January 2009 14:17:16 Sheng Yang wrote:
>>>       
>>>> On Wednesday 14 January 2009 21:53:10 Avi Kivity wrote:
>>>>         
>>>>> Signed-off-by: Avi Kivity <avi@redhat.com>
>>>>>           
>>>> Do we need a lock for the table?
>>>>         
>>> And kvm_add_irq_route/kvm_del_irq_route should be generic used, how about
>>> transfer a kvm_irq_routing_entry as parameter?
>>>       
>> These structures + selectors + unions are clumsy.  For libkvm, I'd
>> prefer adding kvm_add_msi() and kvm_del_msi().
>>     
>
> But...
>   
>> +int kvm_add_irq_route(kvm_context_t kvm, int gsi, int irqchip, int pin)
>> +{
>> +#ifdef KVM_CAP_IRQ_ROUTING
>> +       struct kvm_irq_routing *z;
>> +       struct kvm_irq_routing_entry *e;
>> +       int n, size;
>> +
>> +       if (kvm->irq_routes->nr == kvm->nr_allocated_irq_routes) {
>> +               n = kvm->nr_allocated_irq_routes * 2;
>> +               if (n < 64)
>> +                       n = 64;
>> +               size = sizeof(struct kvm_irq_routing);
>> +               size += n * sizeof(*e);
>> +               z = realloc(kvm->irq_routes, size);
>> +               if (!z)
>> +                       return -ENOMEM;
>> +               kvm->nr_allocated_irq_routes = n;
>> +               kvm->irq_routes = z;
>> +       }
>> +       n = kvm->irq_routes->nr++;
>> +       e = &kvm->irq_routes->entries[n];
>> +       memset(e, 0, sizeof(*e));
>> +       e->gsi = gsi;
>> +       e->type = KVM_IRQ_ROUTING_IRQCHIP;
>> +       e->flags = 0;
>> +       e->u.irqchip.irqchip = irqchip;
>> +       e->u.irqchip.pin = pin;
>> +       return 0;
>> +#else
>> +       return -ENOSYS;
>> +#endif
>> +}
>>     
>
> Besides three lines, all can be reused... I don't see the reason for another 
> function...
>
> And the name here is irq_route, I suppose it should be generic used. Can be 
> core function which can be wrapped.
>   

Yes, I guess we can rename it irqchip_route.  When we add msis, both 
this function and the new msi function can share code.

-- 
error compiling committee.c: too many arguments to function