vduse: Signal vq trigger eventfd directly if possible

Now the vdpa callback will associate an trigger
eventfd in some cases. For performance reasons,
VDUSE can signal it directly during irq injection.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230323053043.35-10-xieyongji@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 77da3685568a182d5a32fd815c82cc168e722f93..8c06f6ab960b237fb4cfd553aa351d0a65f78f7b 100644 (file)
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -459,6 +459,7 @@ static void vduse_dev_reset(struct vduse_dev *dev)
                spin_lock(&vq->irq_lock);
                vq->cb.callback = NULL;
                vq->cb.private = NULL;
+               vq->cb.trigger = NULL;
                spin_unlock(&vq->irq_lock);
                flush_work(&vq->inject);
                flush_work(&vq->kick);
@@ -524,6 +525,7 @@ static void vduse_vdpa_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
        spin_lock(&vq->irq_lock);
        vq->cb.callback = cb->callback;
        vq->cb.private = cb->private;
+       vq->cb.trigger = cb->trigger;
        spin_unlock(&vq->irq_lock);
 }
 
@@ -941,6 +943,23 @@ static void vduse_vq_irq_inject(struct work_struct *work)
        spin_unlock_irq(&vq->irq_lock);
 }
 
+static bool vduse_vq_signal_irqfd(struct vduse_virtqueue *vq)
+{
+       bool signal = false;
+
+       if (!vq->cb.trigger)
+               return false;
+
+       spin_lock_irq(&vq->irq_lock);
+       if (vq->ready && vq->cb.trigger) {
+               eventfd_signal(vq->cb.trigger, 1);
+               signal = true;
+       }
+       spin_unlock_irq(&vq->irq_lock);
+
+       return signal;
+}
+
 static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
                                    struct work_struct *irq_work,
                                    int irq_effective_cpu)
@@ -1243,11 +1262,14 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                if (index >= dev->vq_num)
                        break;
 
+               ret = 0;
                index = array_index_nospec(index, dev->vq_num);
-
-               vduse_vq_update_effective_cpu(dev->vqs[index]);
-               ret = vduse_dev_queue_irq_work(dev, &dev->vqs[index]->inject,
-                                       dev->vqs[index]->irq_effective_cpu);
+               if (!vduse_vq_signal_irqfd(dev->vqs[index])) {
+                       vduse_vq_update_effective_cpu(dev->vqs[index]);
+                       ret = vduse_dev_queue_irq_work(dev,
+                                               &dev->vqs[index]->inject,
+                                               dev->vqs[index]->irq_effective_cpu);
+               }
                break;
        }
        case VDUSE_IOTLB_REG_UMEM: {