vhost-user: introduce virtio API

Add virtio.c and virtio.h that define the functions needed
to manage virtqueues.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>

1 files changed, 121 insertions, 0 deletions

diff --git a/virtio.h b/virtio.h
new file mode 100644
index 0000000..e334355
--- /dev/null
+++ b/virtio.h
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+/* come parts copied from QEMU subprojects/libvhost-user/libvhost-user.h */
+
+#ifndef VIRTIO_H
+#define VIRTIO_H
+
+#include <stdbool.h>
+#include <linux/vhost_types.h>
+
+#define VIRTQUEUE_MAX_SIZE 1024
+
+#define vu_panic(vdev, ...)		\
+	do {				\
+		(vdev)->broken = true;	\
+		err( __VA_ARGS__ );	\
+	} while (0)
+
+typedef struct VuRing {
+	unsigned int num;
+	struct vring_desc *desc;
+	struct vring_avail *avail;
+	struct vring_used *used;
+	uint64_t log_guest_addr;
+	uint32_t flags;
+} VuRing;
+
+typedef struct VuVirtq {
+	VuRing vring;
+
+	/* Next head to pop */
+	uint16_t last_avail_idx;
+
+	/* Last avail_idx read from VQ. */
+	uint16_t shadow_avail_idx;
+
+	uint16_t used_idx;
+
+	/* Last used index value we have signalled on */
+	uint16_t signalled_used;
+
+	/* Last used index value we have signalled on */
+	bool signalled_used_valid;
+
+	bool notification;
+
+	unsigned int inuse;
+
+	int call_fd;
+	int kick_fd;
+	int err_fd;
+	unsigned int enable;
+	bool started;
+
+	/* Guest addresses of our ring */
+	struct vhost_vring_addr vra;
+} VuVirtq;
+
+typedef struct VuDevRegion {
+	uint64_t gpa;
+	uint64_t size;
+	uint64_t qva;
+	uint64_t mmap_offset;
+	uint64_t mmap_addr;
+} VuDevRegion;
+
+#define VHOST_USER_MAX_QUEUES 2
+
+/*
+ * Set a reasonable maximum number of ram slots, which will be supported by
+ * any architecture.
+ */
+#define VHOST_USER_MAX_RAM_SLOTS 32
+
+typedef struct VuDev {
+	uint32_t nregions;
+	VuDevRegion regions[VHOST_USER_MAX_RAM_SLOTS];
+	VuVirtq vq[VHOST_USER_MAX_QUEUES];
+	uint64_t features;
+	uint64_t protocol_features;
+	bool broken;
+	int hdrlen;
+} VuDev;
+
+typedef struct VuVirtqElement {
+	unsigned int index;
+	unsigned int out_num;
+	unsigned int in_num;
+	struct iovec *in_sg;
+	struct iovec *out_sg;
+} VuVirtqElement;
+
+static inline bool has_feature(uint64_t features, unsigned int fbit)
+{
+	return !!(features & (1ULL << fbit));
+}
+
+static inline bool vu_has_feature(VuDev *vdev, unsigned int fbit)
+{
+	return has_feature(vdev->features, fbit);
+}
+
+static inline bool vu_has_protocol_feature(VuDev *vdev, unsigned int fbit)
+{
+	return has_feature(vdev->protocol_features, fbit);
+}
+
+bool vu_queue_empty(VuDev *dev, VuVirtq *vq);
+void vu_queue_notify(VuDev *dev, VuVirtq *vq);
+void *vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz, unsigned char *buffer);
+void vu_queue_detach_element(VuDev *dev, VuVirtq *vq, unsigned int index, size_t len);
+void vu_queue_unpop(VuDev *dev, VuVirtq *vq, unsigned int index, size_t len);
+bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
+
+void vu_queue_fill_by_index(VuDev *dev, VuVirtq *vq, unsigned int index,
+			    unsigned int len, unsigned int idx);
+void vu_queue_fill(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem, unsigned int len,
+		   unsigned int idx);
+void vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int count);
+void vu_queue_push(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem, unsigned int len);
+#endif /* VIRTIO_H */