[net-next RFC V4 PATCH 3/4] virtio: introduce a method to get the irq of a specific virtqueue

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Device specific irq optimizations such as irq affinity may be used by virtio
drivers. So this patch introduce a new method to get the irq of a specific
virtqueue.

After this patch, virtio device drivers could query the irq and do device
specific optimizations. First user would be virtio-net.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
 drivers/lguest/lguest_device.c |    8 ++++++++
 drivers/s390/kvm/kvm_virtio.c  |    6 ++++++
 drivers/virtio/virtio_mmio.c   |    8 ++++++++
 drivers/virtio/virtio_pci.c    |   12 ++++++++++++
 include/linux/virtio_config.h  |    4 ++++
 5 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 9e8388e..bcd080f 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -392,6 +392,13 @@ static const char *lg_bus_name(struct virtio_device *vdev)
 	return "";
 }
 
+static int lg_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	struct lguest_vq_info *lvq = vq->priv;
+
+	return lvq->config.irq;
+}
+
 /* The ops structure which hooks everything together. */
 static struct virtio_config_ops lguest_config_ops = {
 	.get_features = lg_get_features,
@@ -404,6 +411,7 @@ static struct virtio_config_ops lguest_config_ops = {
 	.find_vqs = lg_find_vqs,
 	.del_vqs = lg_del_vqs,
 	.bus_name = lg_bus_name,
+	.get_vq_irq = lg_get_vq_irq,
 };
 
 /*
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index d74e9ae..a897de2 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -268,6 +268,11 @@ static const char *kvm_bus_name(struct virtio_device *vdev)
 	return "";
 }
 
+static int kvm_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	return 0x2603;
+}
+
 /*
  * The config ops structure as defined by virtio config
  */
@@ -282,6 +287,7 @@ static struct virtio_config_ops kvm_vq_configspace_ops = {
 	.find_vqs = kvm_find_vqs,
 	.del_vqs = kvm_del_vqs,
 	.bus_name = kvm_bus_name,
+	.get_vq_irq = kvm_get_vq_irq,
 };
 
 /*
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index f5432b6..2ba37ed 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -411,6 +411,13 @@ static const char *vm_bus_name(struct virtio_device *vdev)
 	return vm_dev->pdev->name;
 }
 
+static int vm_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	return platform_get_irq(vm_dev->pdev, 0);
+}
+
 static struct virtio_config_ops virtio_mmio_config_ops = {
 	.get		= vm_get,
 	.set		= vm_set,
@@ -422,6 +429,7 @@ static struct virtio_config_ops virtio_mmio_config_ops = {
 	.get_features	= vm_get_features,
 	.finalize_features = vm_finalize_features,
 	.bus_name	= vm_bus_name,
+	.get_vq_irq     = vm_get_vq_irq,
 };
 
 
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index adb24f2..c062227 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -607,6 +607,17 @@ static const char *vp_bus_name(struct virtio_device *vdev)
 	return pci_name(vp_dev->pci_dev);
 }
 
+static int vp_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct virtio_pci_vq_info *info = vq->priv;
+
+	if (vp_dev->intx_enabled)
+		return vp_dev->pci_dev->irq;
+	else
+		return vp_dev->msix_entries[info->msix_vector].vector;
+}
+
 static struct virtio_config_ops virtio_pci_config_ops = {
 	.get		= vp_get,
 	.set		= vp_set,
@@ -618,6 +629,7 @@ static struct virtio_config_ops virtio_pci_config_ops = {
 	.get_features	= vp_get_features,
 	.finalize_features = vp_finalize_features,
 	.bus_name	= vp_bus_name,
+	.get_vq_irq     = vp_get_vq_irq,
 };
 
 static void virtio_pci_release_dev(struct device *_d)
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index fc457f4..acd6930 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -98,6 +98,9 @@
  *	vdev: the virtio_device
  *      This returns a pointer to the bus name a la pci_name from which
  *      the caller can then copy.
+ * @get_vq_irq: get the irq numer of the specific virt queue.
+ *      vdev: the virtio_device
+ *      vq: the virtqueue
  */
 typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops {
@@ -116,6 +119,7 @@ struct virtio_config_ops {
 	u32 (*get_features)(struct virtio_device *vdev);
 	void (*finalize_features)(struct virtio_device *vdev);
 	const char *(*bus_name)(struct virtio_device *vdev);
+	int (*get_vq_irq)(struct virtio_device *vdev, struct virtqueue *vq);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */
-- 
1.7.1

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