vduse: Support set_vq_affinity callback

Since virtio-vdpa bus driver already support interrupt
affinity spreading mechanism, let's implement the
set_vq_affinity callback to bring it to vduse device.
After we get the virtqueue's affinity, we can spread
IRQs between CPUs in the affinity mask, in a round-robin
manner, to run the irq callback.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20230323053043.35-6-xieyongji@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 98359d87a06f799e16c0c6632bbc7d13e9d05bb1..45aa8703c4b5e5161089ddedb7ec9d32ad17933b 100644 (file)
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -41,6 +41,8 @@
 #define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
 #define VDUSE_MSG_DEFAULT_TIMEOUT 30
 
+#define IRQ_UNBOUND -1
+
 struct vduse_virtqueue {
        u16 index;
        u16 num_max;
@@ -57,6 +59,8 @@ struct vduse_virtqueue {
        struct vdpa_callback cb;
        struct work_struct inject;
        struct work_struct kick;
+       int irq_effective_cpu;
+       struct cpumask irq_affinity;
 };
 
 struct vduse_dev;
@@ -128,6 +132,7 @@ static struct class *vduse_class;
 static struct cdev vduse_ctrl_cdev;
 static struct cdev vduse_cdev;
 static struct workqueue_struct *vduse_irq_wq;
+static struct workqueue_struct *vduse_irq_bound_wq;
 
 static u32 allowed_device_id[] = {
        VIRTIO_ID_BLOCK,
@@ -708,6 +713,15 @@ static u32 vduse_vdpa_get_generation(struct vdpa_device *vdpa)
        return dev->generation;
 }
 
+static int vduse_vdpa_set_vq_affinity(struct vdpa_device *vdpa, u16 idx,
+                                     const struct cpumask *cpu_mask)
+{
+       struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+       cpumask_copy(&dev->vqs[idx]->irq_affinity, cpu_mask);
+       return 0;
+}
+
 static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
                                unsigned int asid,
                                struct vhost_iotlb *iotlb)
@@ -758,6 +772,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
        .get_config             = vduse_vdpa_get_config,
        .set_config             = vduse_vdpa_set_config,
        .get_generation         = vduse_vdpa_get_generation,
+       .set_vq_affinity        = vduse_vdpa_set_vq_affinity,
        .reset                  = vduse_vdpa_reset,
        .set_map                = vduse_vdpa_set_map,
        .free                   = vduse_vdpa_free,
@@ -917,7 +932,8 @@ static void vduse_vq_irq_inject(struct work_struct *work)
 }
 
 static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
-                                   struct work_struct *irq_work)
+                                   struct work_struct *irq_work,
+                                   int irq_effective_cpu)
 {
        int ret = -EINVAL;
 
@@ -926,7 +942,11 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
                goto unlock;
 
        ret = 0;
-       queue_work(vduse_irq_wq, irq_work);
+       if (irq_effective_cpu == IRQ_UNBOUND)
+               queue_work(vduse_irq_wq, irq_work);
+       else
+               queue_work_on(irq_effective_cpu,
+                             vduse_irq_bound_wq, irq_work);
 unlock:
        up_read(&dev->rwsem);
 
@@ -1029,6 +1049,22 @@ unlock:
        return ret;
 }
 
+static void vduse_vq_update_effective_cpu(struct vduse_virtqueue *vq)
+{
+       int curr_cpu = vq->irq_effective_cpu;
+
+       while (true) {
+               curr_cpu = cpumask_next(curr_cpu, &vq->irq_affinity);
+               if (cpu_online(curr_cpu))
+                       break;
+
+               if (curr_cpu >= nr_cpu_ids)
+                       curr_cpu = IRQ_UNBOUND;
+       }
+
+       vq->irq_effective_cpu = curr_cpu;
+}
+
 static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
 {
@@ -1111,7 +1147,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                break;
        }
        case VDUSE_DEV_INJECT_CONFIG_IRQ:
-               ret = vduse_dev_queue_irq_work(dev, &dev->inject);
+               ret = vduse_dev_queue_irq_work(dev, &dev->inject, IRQ_UNBOUND);
                break;
        case VDUSE_VQ_SETUP: {
                struct vduse_vq_config config;
@@ -1198,7 +1234,10 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                        break;
 
                index = array_index_nospec(index, dev->vq_num);
-               ret = vduse_dev_queue_irq_work(dev, &dev->vqs[index]->inject);
+
+               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: {
@@ -1367,10 +1406,12 @@ static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
                        goto err;
 
                dev->vqs[i]->index = i;
+               dev->vqs[i]->irq_effective_cpu = IRQ_UNBOUND;
                INIT_WORK(&dev->vqs[i]->inject, vduse_vq_irq_inject);
                INIT_WORK(&dev->vqs[i]->kick, vduse_vq_kick_work);
                spin_lock_init(&dev->vqs[i]->kick_lock);
                spin_lock_init(&dev->vqs[i]->irq_lock);
+               cpumask_setall(&dev->vqs[i]->irq_affinity);
        }
 
        return 0;
@@ -1858,12 +1899,15 @@ static int vduse_init(void)
        if (ret)
                goto err_cdev;
 
+       ret = -ENOMEM;
        vduse_irq_wq = alloc_workqueue("vduse-irq",
                                WQ_HIGHPRI | WQ_SYSFS | WQ_UNBOUND, 0);
-       if (!vduse_irq_wq) {
-               ret = -ENOMEM;
+       if (!vduse_irq_wq)
                goto err_wq;
-       }
+
+       vduse_irq_bound_wq = alloc_workqueue("vduse-irq-bound", WQ_HIGHPRI, 0);
+       if (!vduse_irq_bound_wq)
+               goto err_bound_wq;
 
        ret = vduse_domain_init();
        if (ret)
@@ -1877,6 +1921,8 @@ static int vduse_init(void)
 err_mgmtdev:
        vduse_domain_exit();
 err_domain:
+       destroy_workqueue(vduse_irq_bound_wq);
+err_bound_wq:
        destroy_workqueue(vduse_irq_wq);
 err_wq:
        cdev_del(&vduse_cdev);
@@ -1896,6 +1942,7 @@ static void vduse_exit(void)
 {
        vduse_mgmtdev_exit();
        vduse_domain_exit();
+       destroy_workqueue(vduse_irq_bound_wq);
        destroy_workqueue(vduse_irq_wq);
        cdev_del(&vduse_cdev);
        device_destroy(vduse_class, vduse_major);