[PATCH v2 08/11] vduse: Add sysfs interface for irq callback affinity

[Xie Yongji]

Add sysfs interface for each vduse virtqueue to
show the affinity and effective affinity for irq
callback.

And we can also use this interface to change the
effective affinity which must be a subset of the
irq callback affinity mask for the virtqueue. This
might be useful for performance tuning when the irq
callback affinity mask contains more than one CPU.

Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 148 ++++++++++++++++++++++++++---
 1 file changed, 137 insertions(+), 11 deletions(-)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 6507a78abc9d..c65f84100e30 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -61,6 +61,7 @@ struct vduse_virtqueue {
 	int irq_effective_cpu;
 	struct cpumask irq_affinity;
 	spinlock_t irq_affinity_lock;
+	struct kobject kobj;
 };
 
 struct vduse_dev;
@@ -1419,6 +1420,120 @@ static const struct file_operations vduse_dev_fops = {
 	.llseek		= noop_llseek,
 };
 
+static ssize_t irq_cb_affinity_show(struct vduse_virtqueue *vq, char *buf)
+{
+	return sprintf(buf, "%*pb\n", cpumask_pr_args(&vq->irq_affinity));
+}
+
+static ssize_t irq_cb_effective_affinity_show(struct vduse_virtqueue *vq,
+					      char *buf)
+{
+	struct cpumask all_mask = CPU_MASK_ALL;
+	const struct cpumask *mask = &all_mask;
+
+	if (vq->irq_effective_cpu != -1)
+		mask = get_cpu_mask(vq->irq_effective_cpu);
+
+	return sprintf(buf, "%*pb\n", cpumask_pr_args(mask));
+}
+
+static ssize_t irq_cb_effective_affinity_store(struct vduse_virtqueue *vq,
+					       const char *buf, size_t count)
+{
+	cpumask_var_t new_value;
+	int ret;
+
+	if (!zalloc_cpumask_var(&new_value, GFP_KERNEL))
+		return -ENOMEM;
+
+	ret = cpumask_parse(buf, new_value);
+	if (ret)
+		goto free_mask;
+
+	ret = -EINVAL;
+	if (!cpumask_intersects(new_value, &vq->irq_affinity))
+		goto free_mask;
+
+	spin_lock(&vq->irq_affinity_lock);
+
+	if (vq->irq_effective_cpu != -1)
+		per_cpu(vduse_allocated_irq, vq->irq_effective_cpu) -= 1;
+
+	vq->irq_effective_cpu = cpumask_first(new_value);
+	per_cpu(vduse_allocated_irq, vq->irq_effective_cpu) += 1;
+
+	spin_unlock(&vq->irq_affinity_lock);
+	ret = count;
+
+free_mask:
+	free_cpumask_var(new_value);
+	return ret;
+}
+
+struct vq_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct vduse_virtqueue *vq, char *buf);
+	ssize_t (*store)(struct vduse_virtqueue *vq, const char *buf,
+			 size_t count);
+};
+
+static struct vq_sysfs_entry irq_cb_affinity_attr = __ATTR_RO(irq_cb_affinity);
+static struct vq_sysfs_entry irq_cb_effective_affinity_attr =
+					__ATTR_RW(irq_cb_effective_affinity);
+
+static struct attribute *vq_attrs[] = {
+	&irq_cb_affinity_attr.attr,
+	&irq_cb_effective_affinity_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(vq);
+
+static ssize_t vq_attr_show(struct kobject *kobj, struct attribute *attr,
+			    char *buf)
+{
+	struct vduse_virtqueue *vq = container_of(kobj,
+					struct vduse_virtqueue, kobj);
+	struct vq_sysfs_entry *entry = container_of(attr,
+					struct vq_sysfs_entry, attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(vq, buf);
+}
+
+static ssize_t vq_attr_store(struct kobject *kobj, struct attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct vduse_virtqueue *vq = container_of(kobj,
+					struct vduse_virtqueue, kobj);
+	struct vq_sysfs_entry *entry = container_of(attr,
+					struct vq_sysfs_entry, attr);
+
+	if (!entry->store)
+		return -EIO;
+
+	return entry->store(vq, buf, count);
+}
+
+static const struct sysfs_ops vq_sysfs_ops = {
+	.show = vq_attr_show,
+	.store = vq_attr_store,
+};
+
+static void vq_release(struct kobject *kobj)
+{
+	struct vduse_virtqueue *vq = container_of(kobj,
+					struct vduse_virtqueue, kobj);
+	kfree(vq);
+}
+
+static struct kobj_type vq_type = {
+	.release	= vq_release,
+	.sysfs_ops	= &vq_sysfs_ops,
+	.default_groups	= vq_groups,
+};
+
 static void vduse_dev_deinit_vqs(struct vduse_dev *dev)
 {
 	int i;
@@ -1427,13 +1542,13 @@ static void vduse_dev_deinit_vqs(struct vduse_dev *dev)
 		return;
 
 	for (i = 0; i < dev->vq_num; i++)
-		kfree(dev->vqs[i]);
+		kobject_put(&dev->vqs[i]->kobj);
 	kfree(dev->vqs);
 }
 
 static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
 {
-	int i;
+	int ret, i;
 
 	dev->vq_align = vq_align;
 	dev->vq_num = vq_num;
@@ -1443,8 +1558,10 @@ static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
 
 	for (i = 0; i < vq_num; i++) {
 		dev->vqs[i] = kzalloc(sizeof(*dev->vqs[i]), GFP_KERNEL);
-		if (!dev->vqs[i])
+		if (!dev->vqs[i]) {
+			ret = -ENOMEM;
 			goto err;
+		}
 
 		dev->vqs[i]->index = i;
 		dev->vqs[i]->irq_effective_cpu = -1;
@@ -1454,15 +1571,23 @@ static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
 		spin_lock_init(&dev->vqs[i]->irq_lock);
 		spin_lock_init(&dev->vqs[i]->irq_affinity_lock);
 		cpumask_setall(&dev->vqs[i]->irq_affinity);
+
+		kobject_init(&dev->vqs[i]->kobj, &vq_type);
+		ret = kobject_add(&dev->vqs[i]->kobj,
+				  &dev->dev->kobj, "vq%d", i);
+		if (ret) {
+			kfree(dev->vqs[i]);
+			goto err;
+		}
 	}
 
 	return 0;
 err:
 	while (i--)
-		kfree(dev->vqs[i]);
+		kobject_put(&dev->vqs[i]->kobj);
 	kfree(dev->vqs);
 	dev->vqs = NULL;
-	return -ENOMEM;
+	return ret;
 }
 
 static struct vduse_dev *vduse_dev_create(void)
@@ -1637,10 +1762,6 @@ static int vduse_create_dev(struct vduse_dev_config *config,
 	dev->config = config_buf;
 	dev->config_size = config->config_size;
 
-	ret = vduse_dev_init_vqs(dev, config->vq_align, config->vq_num);
-	if (ret)
-		goto err_vqs;
-
 	ret = idr_alloc(&vduse_idr, dev, 1, VDUSE_DEV_MAX, GFP_KERNEL);
 	if (ret < 0)
 		goto err_idr;
@@ -1654,14 +1775,19 @@ static int vduse_create_dev(struct vduse_dev_config *config,
 		ret = PTR_ERR(dev->dev);
 		goto err_dev;
 	}
+
+	ret = vduse_dev_init_vqs(dev, config->vq_align, config->vq_num);
+	if (ret)
+		goto err_vqs;
+
 	__module_get(THIS_MODULE);
 
 	return 0;
+err_vqs:
+	device_destroy(vduse_class, MKDEV(MAJOR(vduse_major), dev->minor));
 err_dev:
 	idr_remove(&vduse_idr, dev->minor);
 err_idr:
-	vduse_dev_deinit_vqs(dev);
-err_vqs:
 	vduse_domain_destroy(dev->domain);
 err_domain:
 	kfree(dev->name);
-- 
2.20.1