[PATCH 2/2] tools/virtio: virtio_test tool

["Michael S. Tsirkin" <mst@redhat.com>]

This is the userspace part of the tool: it includes a bunch of stubs for
linux APIs, somewhat simular to linuxsched. This makes it possible to
recompile the ring code in userspace.

A small test example is implemented combining this with vhost_test
module.

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

---

diff --git a/tools/virtio/Makefile b/tools/virtio/Makefile
new file mode 100644
index 0000000..d1d442e
--- /dev/null
+++ b/tools/virtio/Makefile
@@ -0,0 +1,12 @@
+all: test mod
+test: virtio_test
+virtio_test: virtio_ring.o virtio_test.o
+CFLAGS += -g -O2 -Wall -I. -I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow  -MMD
+vpath %.c ../../drivers/virtio
+mod:
+	${MAKE} -C `pwd`/../.. M=`pwd`/vhost_test
+.PHONY: all test mod clean
+clean:
+	${RM} *.o vhost_test/*.o vhost_test/.*.cmd \
+              vhost_test/Module.symvers vhost_test/modules.order *.d
+-include *.d
diff --git a/tools/virtio/linux/device.h b/tools/virtio/linux/device.h
new file mode 100644
index 0000000..4ad7e1d
--- /dev/null
+++ b/tools/virtio/linux/device.h
@@ -0,0 +1,2 @@
+#ifndef LINUX_DEVICE_H
+#endif
diff --git a/tools/virtio/linux/slab.h b/tools/virtio/linux/slab.h
new file mode 100644
index 0000000..81baeac
--- /dev/null
+++ b/tools/virtio/linux/slab.h
@@ -0,0 +1,2 @@
+#ifndef LINUX_SLAB_H
+#endif
diff --git a/tools/virtio/linux/virtio.h b/tools/virtio/linux/virtio.h
new file mode 100644
index 0000000..669bcdd
--- /dev/null
+++ b/tools/virtio/linux/virtio.h
@@ -0,0 +1,223 @@
+#ifndef LINUX_VIRTIO_H
+#define LINUX_VIRTIO_H
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include <linux/types.h>
+#include <errno.h>
+
+typedef unsigned long long dma_addr_t;
+
+struct scatterlist {
+	unsigned long	page_link;
+	unsigned int	offset;
+	unsigned int	length;
+	dma_addr_t	dma_address;
+};
+
+struct page {
+	unsigned long long dummy;
+};
+
+#define BUG_ON(__BUG_ON_cond) assert(!(__BUG_ON_cond))
+
+/* Physical == Virtual */
+#define virt_to_phys(p) ((unsigned long)p)
+#define phys_to_virt(a) ((void *)(unsigned long)(a))
+/* Page address: Virtual / 4K */
+#define virt_to_page(p) ((struct page*)((virt_to_phys(p) / 4096) * \
+					sizeof(struct page)))
+#define offset_in_page(p) (((unsigned long)p) % 4096)
+#define sg_phys(sg) ((sg->page_link & ~0x3) / sizeof(struct page) * 4096 + \
+		     sg->offset)
+static inline void sg_mark_end(struct scatterlist *sg)
+{
+	/*
+	 * Set termination bit, clear potential chain bit
+	 */
+	sg->page_link |= 0x02;
+	sg->page_link &= ~0x01;
+}
+static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
+{
+	memset(sgl, 0, sizeof(*sgl) * nents);
+	sg_mark_end(&sgl[nents - 1]);
+}
+static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
+{
+	unsigned long page_link = sg->page_link & 0x3;
+
+	/*
+	 * In order for the low bit stealing approach to work, pages
+	 * must be aligned at a 32-bit boundary as a minimum.
+	 */
+	BUG_ON((unsigned long) page & 0x03);
+	sg->page_link = page_link | (unsigned long) page;
+}
+
+static inline void sg_set_page(struct scatterlist *sg, struct page *page,
+			       unsigned int len, unsigned int offset)
+{
+	sg_assign_page(sg, page);
+	sg->offset = offset;
+	sg->length = len;
+}
+
+static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
+			      unsigned int buflen)
+{
+	sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
+}
+
+static inline void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
+{
+	sg_init_table(sg, 1);
+	sg_set_buf(sg, buf, buflen);
+}
+
+typedef __u16 u16;
+
+typedef enum {
+	GFP_KERNEL,
+	GFP_ATOMIC,
+} gfp_t;
+typedef enum {
+	IRQ_NONE,
+	IRQ_HANDLED
+} irqreturn_t;
+
+static inline void *kmalloc(size_t s, gfp_t gfp)
+{
+	return malloc(s);
+}
+
+static inline void kfree(void *p)
+{
+	free(p);
+}
+
+#define container_of(ptr, type, member) ({			\
+	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+
+#define uninitialized_var(x) x = x
+
+# ifndef likely
+#  define likely(x)	(__builtin_expect(!!(x), 1))
+# endif
+# ifndef unlikely
+#  define unlikely(x)	(__builtin_expect(!!(x), 0))
+# endif
+
+#define pr_err(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
+#ifdef DEBUG
+#define pr_debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
+#else
+#define pr_debug(format, ...) do {} while (0)
+#endif
+#define dev_err(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)
+#define dev_warn(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)
+
+/* TODO: empty stubs for now. Broken but enough for virtio_ring.c */
+#define list_add_tail(a, b) do {} while (0)
+#define list_del(a) do {} while (0)
+
+#define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
+#define BITS_PER_BYTE		8
+#define BITS_PER_LONG (sizeof(long) * BITS_PER_BYTE)
+#define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
+/* TODO: Not atomic as it should be:
+ * we don't use this for anything important. */
+static inline void clear_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+	*p &= ~mask;
+}
+
+static inline int test_bit(int nr, const volatile unsigned long *addr)
+{
+        return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+}
+
+/* The only feature we care to support */
+#define virtio_has_feature(dev, feature) \
+	test_bit((feature), (dev)->features)
+/* end of stubs */
+
+struct virtio_device {
+	void *dev;
+	unsigned long features[1];
+};
+
+struct virtqueue {
+	/* TODO: commented as list macros are empty stubs for now.
+	 * Broken but enough for virtio_ring.c
+	 * struct list_head list; */
+	void (*callback)(struct virtqueue *vq);
+	const char *name;
+	struct virtio_device *vdev;
+	void *priv;
+};
+
+#define EXPORT_SYMBOL_GPL(__EXPORT_SYMBOL_GPL_name) \
+	void __EXPORT_SYMBOL_GPL##__EXPORT_SYMBOL_GPL_name() { \
+}
+#define MODULE_LICENSE(__MODULE_LICENSE_value) \
+	const char *__MODULE_LICENSE_name = __MODULE_LICENSE_value
+
+#define CONFIG_SMP
+
+#if defined(__i386__) || defined(__x86_64__)
+#define barrier() asm volatile("" ::: "memory")
+#define mb() __sync_synchronize()
+
+#define smp_mb()	mb()
+# define smp_rmb()	barrier()
+# define smp_wmb()	barrier()
+#else
+#error Please fill in barrier macros
+#endif
+
+/* Interfaces exported by virtio_ring. */
+int virtqueue_add_buf_gfp(struct virtqueue *vq,
+			  struct scatterlist sg[],
+			  unsigned int out_num,
+			  unsigned int in_num,
+			  void *data,
+			  gfp_t gfp);
+
+static inline int virtqueue_add_buf(struct virtqueue *vq,
+				    struct scatterlist sg[],
+				    unsigned int out_num,
+				    unsigned int in_num,
+				    void *data)
+{
+	return virtqueue_add_buf_gfp(vq, sg, out_num, in_num, data, GFP_ATOMIC);
+}
+
+void virtqueue_kick(struct virtqueue *vq);
+
+void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
+
+void virtqueue_disable_cb(struct virtqueue *vq);
+
+bool virtqueue_enable_cb(struct virtqueue *vq);
+
+void *virtqueue_detach_unused_buf(struct virtqueue *vq);
+struct virtqueue *vring_new_virtqueue(unsigned int num,
+				      unsigned int vring_align,
+				      struct virtio_device *vdev,
+				      void *pages,
+				      void (*notify)(struct virtqueue *vq),
+				      void (*callback)(struct virtqueue *vq),
+				      const char *name);
+void vring_del_virtqueue(struct virtqueue *vq);
+
+#endif
diff --git a/tools/virtio/vhost_test/Makefile b/tools/virtio/vhost_test/Makefile
new file mode 100644
index 0000000..a1d35b8
--- /dev/null
+++ b/tools/virtio/vhost_test/Makefile
@@ -0,0 +1,2 @@
+obj-m += vhost_test.o
+EXTRA_CFLAGS += -Idrivers/vhost
diff --git a/tools/virtio/vhost_test/vhost_test.c b/tools/virtio/vhost_test/vhost_test.c
new file mode 100644
index 0000000..1873518
--- /dev/null
+++ b/tools/virtio/vhost_test/vhost_test.c
@@ -0,0 +1 @@
+#include "test.c"
diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
new file mode 100644
index 0000000..808ae86
--- /dev/null
+++ b/tools/virtio/virtio_test.c
@@ -0,0 +1,248 @@
+#define _GNU_SOURCE
+#include <getopt.h>
+#include <string.h>
+#include <poll.h>
+#include <sys/eventfd.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <linux/vhost.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ring.h>
+#include "../../drivers/vhost/test.h"
+
+struct vq_info {
+	int kick;
+	int call;
+	int num;
+	int idx;
+	void *ring;
+	/* copy used for control */
+	struct vring vring;
+	struct virtqueue *vq;
+};
+
+struct vdev_info {
+	struct virtio_device vdev;
+	int control;
+	struct pollfd fds[1];
+	struct vq_info vqs[1];
+	int nvqs;
+	void *buf;
+	size_t buf_size;
+	struct vhost_memory *mem;
+};
+
+void vq_notify(struct virtqueue *vq)
+{
+	struct vq_info *info = vq->priv;
+	unsigned long long v = 1;
+	int r;
+	r = write(info->kick, &v, sizeof v);
+	assert(r == sizeof v);
+}
+
+void vq_callback(struct virtqueue *vq)
+{
+}
+
+
+void vhost_vq_setup(struct vdev_info *dev, struct vq_info *info)
+{
+	struct vhost_vring_state state = { .index = info->idx };
+	struct vhost_vring_file file = { .index = info->idx };
+	unsigned long long features = dev->vdev.features[0];
+	struct vhost_vring_addr addr = {
+		.index = info->idx,
+		.desc_user_addr = (uint64_t)(unsigned long)info->vring.desc,
+		.avail_user_addr = (uint64_t)(unsigned long)info->vring.avail,
+		.used_user_addr = (uint64_t)(unsigned long)info->vring.used,
+	};
+	int r;
+	r = ioctl(dev->control, VHOST_SET_FEATURES, &features);
+	assert(r >= 0);
+	state.num = info->vring.num;
+	r = ioctl(dev->control, VHOST_SET_VRING_NUM, &state);
+	assert(r >= 0);
+	state.num = 0;
+	r = ioctl(dev->control, VHOST_SET_VRING_BASE, &state);
+	assert(r >= 0);
+	r = ioctl(dev->control, VHOST_SET_VRING_ADDR, &addr);
+	assert(r >= 0);
+	file.fd = info->kick;
+	r = ioctl(dev->control, VHOST_SET_VRING_KICK, &file);
+	assert(r >= 0);
+	file.fd = info->call;
+	r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);
+	assert(r >= 0);
+}
+
+static void vq_info_add(struct vdev_info *dev, int num)
+{
+	struct vq_info *info = &dev->vqs[dev->nvqs];
+	int r;
+	info->idx = dev->nvqs;
+	info->kick = eventfd(0, EFD_NONBLOCK);
+	info->call = eventfd(0, EFD_NONBLOCK);
+	r = posix_memalign(&info->ring, 4096, vring_size(num, 4096));
+	assert(r >= 0);
+	memset(info->ring, 0, vring_size(num, 4096));
+	vring_init(&info->vring, num, info->ring, 4096);
+	info->vq = vring_new_virtqueue(info->vring.num, 4096, &dev->vdev, info->ring,
+				       vq_notify, vq_callback, "test");
+	assert(info->vq);
+	info->vq->priv = info;
+	vhost_vq_setup(dev, info);
+	dev->fds[info->idx].fd = info->call;
+	dev->fds[info->idx].events = POLLIN;
+	dev->nvqs++;
+}
+
+static void vdev_info_init(struct vdev_info* dev, unsigned long long features)
+{
+	int r;
+	memset(dev, 0, sizeof *dev);
+	dev->vdev.features[0] = features;
+	dev->vdev.features[1] = features >> 32;
+	dev->buf_size = 1024;
+	dev->buf = malloc(dev->buf_size);
+	assert(dev->buf);
+        dev->control = open("/dev/vhost-test", O_RDWR);
+	assert(dev->control >= 0);
+	r = ioctl(dev->control, VHOST_SET_OWNER, NULL);
+	assert(r >= 0);
+	dev->mem = malloc(offsetof(struct vhost_memory, regions) +
+			  sizeof dev->mem->regions[0]);
+	assert(dev->mem);
+	memset(dev->mem, 0, offsetof(struct vhost_memory, regions) +
+                          sizeof dev->mem->regions[0]);
+	dev->mem->nregions = 1;
+	dev->mem->regions[0].guest_phys_addr = (long)dev->buf;
+	dev->mem->regions[0].userspace_addr = (long)dev->buf;
+	dev->mem->regions[0].memory_size = dev->buf_size;
+	r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
+	assert(r >= 0);
+}
+
+/* TODO: this is pretty bad: we get a cache line bounce
+ * for the wait queue on poll and another one on read,
+ * plus the read which is there just to clear the
+ * current state. */
+static void wait_for_interrupt(struct vdev_info *dev)
+{
+	int i;
+	unsigned long long val;
+	poll(dev->fds, dev->nvqs, -1);
+	for (i = 0; i < dev->nvqs; ++i)
+		if (dev->fds[i].revents & POLLIN) {
+			read(dev->fds[i].fd, &val, sizeof val);
+		}
+}
+
+static void run_test(struct vdev_info *dev, struct vq_info *vq, int bufs)
+{
+	struct scatterlist sl;
+	long started = 0, completed = 0;
+	long completed_before;
+	int r, test = 1;
+	unsigned len;
+	long long spurious = 0;
+	r = ioctl(dev->control, VHOST_TEST_RUN, &test);
+	assert(r >= 0);
+	for (;;) {
+		virtqueue_disable_cb(vq->vq);
+		completed_before = completed;
+		do {
+			if (started < bufs) {
+				sg_init_one(&sl, dev->buf, dev->buf_size);
+				r = virtqueue_add_buf(vq->vq, &sl, 1, 0,
+						      dev->buf + started);
+				if (likely(r >= 0)) {
+					++started;
+					virtqueue_kick(vq->vq);
+				}
+			} else
+				r = -1;
+
+			/* Flush out completed bufs if any */
+			if (virtqueue_get_buf(vq->vq, &len)) {
+				++completed;
+				r = 0;
+			}
+			
+		} while (r >= 0);
+		if (completed == completed_before)
+			++spurious;
+		assert(completed <= bufs);
+		assert(started <= bufs);
+		if (completed == bufs)
+			break;
+		if (virtqueue_enable_cb(vq->vq)) {
+			wait_for_interrupt(dev);
+		}
+	}
+	test = 0;
+	r = ioctl(dev->control, VHOST_TEST_RUN, &test);
+	assert(r >= 0);
+	fprintf(stderr, "spurious wakeus: 0x%llx\n", spurious);
+}
+
+const char optstring[] = "h";
+const struct option longopts[] = {
+	{
+		.name = "help",
+		.val = 'h',
+	},
+	{
+		.name = "indirect",
+		.val = 'I',
+	},
+	{
+		.name = "no-indirect",
+		.val = 'i',
+	},
+	{
+	}
+};
+
+static void help()
+{
+	fprintf(stderr, "Usage: virtio_test [--help] [--no-indirect]\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct vdev_info dev;
+	unsigned long long features = 1ULL << VIRTIO_RING_F_INDIRECT_DESC;
+	int o;
+
+	for (;;) {
+		o = getopt_long(argc, argv, optstring, longopts, NULL);
+		switch (o) {
+		case -1:
+			goto done;
+		case '?':
+			help();
+			exit(2);
+		case 'h':
+			help();
+			goto done;
+		case 'i':
+			features &= ~(1ULL << VIRTIO_RING_F_INDIRECT_DESC);
+			break;
+		default:
+			assert(0);
+			break;
+		}
+	}
+
+done:
+	vdev_info_init(&dev, features);
+	vq_info_add(&dev, 256);
+	run_test(&dev, &dev.vqs[0], 0x100000);
+	return 0;
+}