vhost test module

This adds a test module for vhost infrastructure.
Intentionally not tied to kbuild to prevent people
from installing and loading it accidentally.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 327 insertions, 0 deletions

diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
new file mode 100644
index 00000000000..099f30230d0
--- /dev/null
+++ b/drivers/vhost/test.c
@@ -0,0 +1,320 @@
+/* Copyright (C) 2009 Red Hat, Inc.
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * test virtio server in host kernel.
+ */
+
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/rcupdate.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+
+#include "test.h"
+#include "vhost.c"
+
+/* Max number of bytes transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others. */
+#define VHOST_TEST_WEIGHT 0x80000
+
+enum {
+        VHOST_TEST_VQ = 0,
+        VHOST_TEST_VQ_MAX = 1,
+};
+
+struct vhost_test {
+        struct vhost_dev dev;
+        struct vhost_virtqueue vqs[VHOST_TEST_VQ_MAX];
+};
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_vq(struct vhost_test *n)
+{
+        struct vhost_virtqueue *vq = &n->dev.vqs[VHOST_TEST_VQ];
+        unsigned out, in;
+        int head;
+        size_t len, total_len = 0;
+        void *private;
+
+        private = rcu_dereference_check(vq->private_data, 1);
+        if (!private)
+                return;
+
+        mutex_lock(&vq->mutex);
+        vhost_disable_notify(vq);
+
+        for (;;) {
+                head = vhost_get_vq_desc(&n->dev, vq, vq->iov,
+                                         ARRAY_SIZE(vq->iov),
+                                         &out, &in,
+                                         NULL, NULL);
+                /* On error, stop handling until the next kick. */
+                if (unlikely(head < 0))
+                        break;
+                /* Nothing new?  Wait for eventfd to tell us they refilled. */
+                if (head == vq->num) {
+                        if (unlikely(vhost_enable_notify(vq))) {
+                                vhost_disable_notify(vq);
+                                continue;
+                        }
+                        break;
+                }
+                if (in) {
+                        vq_err(vq, "Unexpected descriptor format for TX: "
+                               "out %d, int %d\n", out, in);
+                        break;
+                }
+                len = iov_length(vq->iov, out);
+                /* Sanity check */
+                if (!len) {
+                        vq_err(vq, "Unexpected 0 len for TX\n");
+                        break;
+                }
+                vhost_add_used_and_signal(&n->dev, vq, head, 0);
+                total_len += len;
+                if (unlikely(total_len >= VHOST_TEST_WEIGHT)) {
+                        vhost_poll_queue(&vq->poll);
+                        break;
+                }
+        }
+
+        mutex_unlock(&vq->mutex);
+}
+
+static void handle_vq_kick(struct vhost_work *work)
+{
+        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+                                                  poll.work);
+        struct vhost_test *n = container_of(vq->dev, struct vhost_test, dev);
+
+        handle_vq(n);
+}
+
+static int vhost_test_open(struct inode *inode, struct file *f)
+{
+        struct vhost_test *n = kmalloc(sizeof *n, GFP_KERNEL);
+        struct vhost_dev *dev;
+        int r;
+
+        if (!n)
+                return -ENOMEM;
+
+        dev = &n->dev;
+        n->vqs[VHOST_TEST_VQ].handle_kick = handle_vq_kick;
+        r = vhost_dev_init(dev, n->vqs, VHOST_TEST_VQ_MAX);
+        if (r < 0) {
+                kfree(n);
+                return r;
+        }
+
+        f->private_data = n;
+
+        return 0;
+}
+
+static void *vhost_test_stop_vq(struct vhost_test *n,
+                                struct vhost_virtqueue *vq)
+{
+        void *private;
+
+        mutex_lock(&vq->mutex);
+        private = rcu_dereference_protected(vq->private_data,
+                                         lockdep_is_held(&vq->mutex));
+        rcu_assign_pointer(vq->private_data, NULL);
+        mutex_unlock(&vq->mutex);
+        return private;
+}
+
+static void vhost_test_stop(struct vhost_test *n, void **privatep)
+{
+        *privatep = vhost_test_stop_vq(n, n->vqs + VHOST_TEST_VQ);
+}
+
+static void vhost_test_flush_vq(struct vhost_test *n, int index)
+{
+        vhost_poll_flush(&n->dev.vqs[index].poll);
+}
+
+static void vhost_test_flush(struct vhost_test *n)
+{
+        vhost_test_flush_vq(n, VHOST_TEST_VQ);
+}
+
+static int vhost_test_release(struct inode *inode, struct file *f)
+{
+        struct vhost_test *n = f->private_data;
+        void  *private;
+
+        vhost_test_stop(n, &private);
+        vhost_test_flush(n);
+        vhost_dev_cleanup(&n->dev);
+        /* We do an extra flush before freeing memory,
+         * since jobs can re-queue themselves. */
+        vhost_test_flush(n);
+        kfree(n);
+        return 0;
+}
+
+static long vhost_test_run(struct vhost_test *n, int test)
+{
+        void *priv, *oldpriv;
+        struct vhost_virtqueue *vq;
+        int r, index;
+
+        if (test < 0 || test > 1)
+                return -EINVAL;
+
+        mutex_lock(&n->dev.mutex);
+        r = vhost_dev_check_owner(&n->dev);
+        if (r)
+                goto err;
+
+        for (index = 0; index < n->dev.nvqs; ++index) {
+                /* Verify that ring has been setup correctly. */
+                if (!vhost_vq_access_ok(&n->vqs[index])) {
+                        r = -EFAULT;
+                        goto err;
+                }
+        }
+
+        for (index = 0; index < n->dev.nvqs; ++index) {
+                vq = n->vqs + index;
+                mutex_lock(&vq->mutex);
+                priv = test ? n : NULL;
+
+                /* start polling new socket */
+                oldpriv = rcu_dereference_protected(vq->private_data,
+                                                    lockdep_is_held(&vq->mutex));
+                rcu_assign_pointer(vq->private_data, priv);
+
+                mutex_unlock(&vq->mutex);
+
+                if (oldpriv) {
+                        vhost_test_flush_vq(n, index);
+                }
+        }
+
+        mutex_unlock(&n->dev.mutex);
+        return 0;
+
+err:
+        mutex_unlock(&n->dev.mutex);
+        return r;
+}
+
+static long vhost_test_reset_owner(struct vhost_test *n)
+{
+        void *priv = NULL;
+        long err;
+        mutex_lock(&n->dev.mutex);
+        err = vhost_dev_check_owner(&n->dev);
+        if (err)
+                goto done;
+        vhost_test_stop(n, &priv);
+        vhost_test_flush(n);
+        err = vhost_dev_reset_owner(&n->dev);
+done:
+        mutex_unlock(&n->dev.mutex);
+        return err;
+}
+
+static int vhost_test_set_features(struct vhost_test *n, u64 features)
+{
+        mutex_lock(&n->dev.mutex);
+        if ((features & (1 << VHOST_F_LOG_ALL)) &&
+            !vhost_log_access_ok(&n->dev)) {
+                mutex_unlock(&n->dev.mutex);
+                return -EFAULT;
+        }
+        n->dev.acked_features = features;
+        smp_wmb();
+        vhost_test_flush(n);
+        mutex_unlock(&n->dev.mutex);
+        return 0;
+}
+
+static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
+                             unsigned long arg)
+{
+        struct vhost_test *n = f->private_data;
+        void __user *argp = (void __user *)arg;
+        u64 __user *featurep = argp;
+        int test;
+        u64 features;
+        int r;
+        switch (ioctl) {
+        case VHOST_TEST_RUN:
+                if (copy_from_user(&test, argp, sizeof test))
+                        return -EFAULT;
+                return vhost_test_run(n, test);
+        case VHOST_GET_FEATURES:
+                features = VHOST_FEATURES;
+                if (copy_to_user(featurep, &features, sizeof features))
+                        return -EFAULT;
+                return 0;
+        case VHOST_SET_FEATURES:
+                if (copy_from_user(&features, featurep, sizeof features))
+                        return -EFAULT;
+                if (features & ~VHOST_FEATURES)
+                        return -EOPNOTSUPP;
+                return vhost_test_set_features(n, features);
+        case VHOST_RESET_OWNER:
+                return vhost_test_reset_owner(n);
+        default:
+                mutex_lock(&n->dev.mutex);
+                r = vhost_dev_ioctl(&n->dev, ioctl, arg);
+                vhost_test_flush(n);
+                mutex_unlock(&n->dev.mutex);
+                return r;
+        }
+}
+
+#ifdef CONFIG_COMPAT
+static long vhost_test_compat_ioctl(struct file *f, unsigned int ioctl,
+                                   unsigned long arg)
+{
+        return vhost_test_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static const struct file_operations vhost_test_fops = {
+        .owner          = THIS_MODULE,
+        .release        = vhost_test_release,
+        .unlocked_ioctl = vhost_test_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = vhost_test_compat_ioctl,
+#endif
+        .open           = vhost_test_open,
+        .llseek         = noop_llseek,
+};
+
+static struct miscdevice vhost_test_misc = {
+        MISC_DYNAMIC_MINOR,
+        "vhost-test",
+        &vhost_test_fops,
+};
+
+static int vhost_test_init(void)
+{
+        return misc_register(&vhost_test_misc);
+}
+module_init(vhost_test_init);
+
+static void vhost_test_exit(void)
+{
+        misc_deregister(&vhost_test_misc);
+}
+module_exit(vhost_test_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Michael S. Tsirkin");
+MODULE_DESCRIPTION("Host kernel side for virtio simulator");
diff --git a/drivers/vhost/test.h b/drivers/vhost/test.h
new file mode 100644
index 00000000000..1fef5df8215
--- /dev/null
+++ b/drivers/vhost/test.h
@@ -0,0 +1,7 @@
+#ifndef LINUX_VHOST_TEST_H
+#define LINUX_VHOST_TEST_H
+
+/* Start a given test on the virtio null device. 0 stops all tests. */
+#define VHOST_TEST_RUN _IOW(VHOST_VIRTIO, 0x31, int)
+
+#endif