[PATCH] KVM: Split up MSI-X assigned device IRQ handler

[PATCH] KVM: Split up MSI-X assigned device IRQ handler

[Jan Kiszka]

The threaded IRQ handler for MSI-X has almost nothing in common with the
INTx/MSI handler. Move its code into a dedicated handler.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 virt/kvm/assigned-dev.c |   32 +++++++++++++++++++-------------
 1 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 84ead54..7debe8c 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -58,8 +58,6 @@ static int find_index_from_host_irq(struct kvm_assigned_dev_kernel
 static irqreturn_t kvm_assigned_dev_thread(int irq, void *dev_id)
 {
 	struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
-	u32 vector;
-	int index;
 
 	if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_INTX) {
 		spin_lock(&assigned_dev->intx_lock);
@@ -68,20 +66,28 @@ static irqreturn_t kvm_assigned_dev_thread(int irq, void *dev_id)
 		spin_unlock(&assigned_dev->intx_lock);
 	}
 
-	if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
-		index = find_index_from_host_irq(assigned_dev, irq);
-		if (index >= 0) {
-			vector = assigned_dev->
-					guest_msix_entries[index].vector;
-			kvm_set_irq(assigned_dev->kvm,
-				    assigned_dev->irq_source_id, vector, 1);
-		}
-	} else
+	kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
+		    assigned_dev->guest_irq, 1);
+
+	return IRQ_HANDLED;
+}
+
+#ifdef __KVM_HAVE_MSIX
+static irqreturn_t kvm_assigned_dev_thread_msix(int irq, void *dev_id)
+{
+	struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
+	int index = find_index_from_host_irq(assigned_dev, irq);
+	u32 vector;
+
+	if (index >= 0) {
+		vector = assigned_dev->guest_msix_entries[index].vector;
 		kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
-			    assigned_dev->guest_irq, 1);
+			    vector, 1);
+	}
 
 	return IRQ_HANDLED;
 }
+#endif
 
 /* Ack the irq line for an assigned device */
 static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
@@ -279,7 +285,7 @@ static int assigned_device_enable_host_msix(struct kvm *kvm,
 
 	for (i = 0; i < dev->entries_nr; i++) {
 		r = request_threaded_irq(dev->host_msix_entries[i].vector,
-					 NULL, kvm_assigned_dev_thread,
+					 NULL, kvm_assigned_dev_thread_msix,
 					 0, dev->irq_name, dev);
 		if (r)
 			goto err;
-- 
1.7.3.4

RE: [PATCH] KVM: Split up MSI-X assigned device IRQ handler

[Tian, Kevin]

> From: Jan Kiszka
> Sent: Tuesday, September 13, 2011 12:58 AM
> 
> The threaded IRQ handler for MSI-X has almost nothing in common with the
> INTx/MSI handler. Move its code into a dedicated handler.

if it's desired to further go down this cleanup path, there's also no need to
register ack notifier for MSI-X type device since all the logic there is simply
a nop:

static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
{
        struct kvm_assigned_dev_kernel *dev;

        if (kian->gsi == -1)
                return;

        dev = container_of(kian, struct kvm_assigned_dev_kernel,
                           ack_notifier);

        kvm_set_irq(dev->kvm, dev->irq_source_id, dev->guest_irq, 0);

        /* The guest irq may be shared so this ack may be
         * from another device.
         */
        spin_lock(&dev->intx_lock);
        if (dev->host_irq_disabled) {
                enable_irq(dev->host_irq);
                dev->host_irq_disabled = false;
        }
        spin_unlock(&dev->intx_lock);
}

Thanks
Kevin

> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  virt/kvm/assigned-dev.c |   32 +++++++++++++++++++-------------
>  1 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> index 84ead54..7debe8c 100644
> --- a/virt/kvm/assigned-dev.c
> +++ b/virt/kvm/assigned-dev.c
> @@ -58,8 +58,6 @@ static int find_index_from_host_irq(struct
> kvm_assigned_dev_kernel
>  static irqreturn_t kvm_assigned_dev_thread(int irq, void *dev_id)
>  {
>  	struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
> -	u32 vector;
> -	int index;
> 
>  	if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_INTX) {
>  		spin_lock(&assigned_dev->intx_lock);
> @@ -68,20 +66,28 @@ static irqreturn_t kvm_assigned_dev_thread(int irq,
> void *dev_id)
>  		spin_unlock(&assigned_dev->intx_lock);
>  	}
> 
> -	if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
> -		index = find_index_from_host_irq(assigned_dev, irq);
> -		if (index >= 0) {
> -			vector = assigned_dev->
> -					guest_msix_entries[index].vector;
> -			kvm_set_irq(assigned_dev->kvm,
> -				    assigned_dev->irq_source_id, vector, 1);
> -		}
> -	} else
> +	kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
> +		    assigned_dev->guest_irq, 1);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +#ifdef __KVM_HAVE_MSIX
> +static irqreturn_t kvm_assigned_dev_thread_msix(int irq, void *dev_id)
> +{
> +	struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
> +	int index = find_index_from_host_irq(assigned_dev, irq);
> +	u32 vector;
> +
> +	if (index >= 0) {
> +		vector = assigned_dev->guest_msix_entries[index].vector;
>  		kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
> -			    assigned_dev->guest_irq, 1);
> +			    vector, 1);
> +	}
> 
>  	return IRQ_HANDLED;
>  }
> +#endif
> 
>  /* Ack the irq line for an assigned device */
>  static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
> @@ -279,7 +285,7 @@ static int assigned_device_enable_host_msix(struct
> kvm *kvm,
> 
>  	for (i = 0; i < dev->entries_nr; i++) {
>  		r = request_threaded_irq(dev->host_msix_entries[i].vector,
> -					 NULL, kvm_assigned_dev_thread,
> +					 NULL, kvm_assigned_dev_thread_msix,
>  					 0, dev->irq_name, dev);
>  		if (r)
>  			goto err;
> --
> 1.7.3.4
> --
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Re: [PATCH] KVM: Split up MSI-X assigned device IRQ handler

[Jan Kiszka]

On 2011-09-13 08:40, Tian, Kevin wrote:
>> From: Jan Kiszka
>> Sent: Tuesday, September 13, 2011 12:58 AM
>>
>> The threaded IRQ handler for MSI-X has almost nothing in common with the
>> INTx/MSI handler. Move its code into a dedicated handler.
> 
> if it's desired to further go down this cleanup path, there's also no need to
> register ack notifier for MSI-X type device since all the logic there is simply
> a nop:

You mean http://thread.gmane.org/gmane.comp.emulators.kvm.devel/79075? :)

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

RE: [PATCH] KVM: Split up MSI-X assigned device IRQ handler

[Tian, Kevin]

> From: Jan Kiszka [mailto:jan.kiszka@siemens.com]
> Sent: Tuesday, September 13, 2011 3:30 PM
> 
> On 2011-09-13 08:40, Tian, Kevin wrote:
> >> From: Jan Kiszka
> >> Sent: Tuesday, September 13, 2011 12:58 AM
> >>
> >> The threaded IRQ handler for MSI-X has almost nothing in common with the
> >> INTx/MSI handler. Move its code into a dedicated handler.
> >
> > if it's desired to further go down this cleanup path, there's also no need to
> > register ack notifier for MSI-X type device since all the logic there is simply
> > a nop:
> 
> You mean
> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/79075? :)
> 

yes, and sorry that I didn't catch that thread. :-)

Thanks
Kevin

Re: [PATCH] KVM: Split up MSI-X assigned device IRQ handler

[Marcelo Tosatti]

On Mon, Sep 12, 2011 at 06:57:56PM +0200, Jan Kiszka wrote:
> The threaded IRQ handler for MSI-X has almost nothing in common with the
> INTx/MSI handler. Move its code into a dedicated handler.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  virt/kvm/assigned-dev.c |   32 +++++++++++++++++++-------------
>  1 files changed, 19 insertions(+), 13 deletions(-)

Applied, thanks.