virtio: Import virtio_vring.h

This header has no further dependencies. It only has some stable data
types and primitive functions, so we can copy it to include/hw/virtio in
order to allow vring code (and its user virtio-blk dataplane) to be
built unconditionally, even for cross compiling.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1410329871-28885-2-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

2 files changed, 168 insertions, 1 deletions

diff --git a/include/hw/virtio/dataplane/vring.h b/include/hw/virtio/dataplane/vring.h
index af73ee2..d3e086a 100644
--- a/include/hw/virtio/dataplane/vring.h
+++ b/include/hw/virtio/dataplane/vring.h
@@ -17,8 +17,8 @@
 #ifndef VRING_H
 #define VRING_H
 
-#include <linux/virtio_ring.h>
 #include "qemu-common.h"
+#include "hw/virtio/virtio_ring.h"
 #include "hw/virtio/virtio.h"
 
 typedef struct {
diff --git a/include/hw/virtio/virtio_ring.h b/include/hw/virtio/virtio_ring.h
new file mode 100644
index 0000000..8f58bc9
--- /dev/null
+++ b/include/hw/virtio/virtio_ring.h
@@ -0,0 +1,167 @@
+#ifndef _LINUX_VIRTIO_RING_H
+#define _LINUX_VIRTIO_RING_H
+/*
+ * This file is copied from /usr/include/linux while converting __uNN types
+ * to uXX_t, __inline__ to inline, and tab to spaces.
+ * */
+
+/* An interface for efficient virtio implementation, currently for use by KVM
+ * and lguest, but hopefully others soon.  Do NOT change this since it will
+ * break existing servers and clients.
+ *
+ * This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of IBM nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * Copyright Rusty Russell IBM Corporation 2007. */
+
+/* This marks a buffer as continuing via the next field. */
+#define VRING_DESC_F_NEXT   1
+/* This marks a buffer as write-only (otherwise read-only). */
+#define VRING_DESC_F_WRITE  2
+/* This means the buffer contains a list of buffer descriptors. */
+#define VRING_DESC_F_INDIRECT   4
+
+/* The Host uses this in used->flags to advise the Guest: don't kick me when
+ * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
+ * will still kick if it's out of buffers. */
+#define VRING_USED_F_NO_NOTIFY  1
+/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
+ * when you consume a buffer.  It's unreliable, so it's simply an
+ * optimization.  */
+#define VRING_AVAIL_F_NO_INTERRUPT  1
+
+/* We support indirect buffer descriptors */
+#define VIRTIO_RING_F_INDIRECT_DESC 28
+
+/* The Guest publishes the used index for which it expects an interrupt
+ * at the end of the avail ring. Host should ignore the avail->flags field. */
+/* The Host publishes the avail index for which it expects a kick
+ * at the end of the used ring. Guest should ignore the used->flags field. */
+#define VIRTIO_RING_F_EVENT_IDX     29
+
+/* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
+struct vring_desc {
+    /* Address (guest-physical). */
+    uint64_t addr;
+    /* Length. */
+    uint32_t len;
+    /* The flags as indicated above. */
+    uint16_t flags;
+    /* We chain unused descriptors via this, too */
+    uint16_t next;
+};
+
+struct vring_avail {
+    uint16_t flags;
+    uint16_t idx;
+    uint16_t ring[];
+};
+
+/* u32 is used here for ids for padding reasons. */
+struct vring_used_elem {
+    /* Index of start of used descriptor chain. */
+    uint32_t id;
+    /* Total length of the descriptor chain which was used (written to) */
+    uint32_t len;
+};
+
+struct vring_used {
+    uint16_t flags;
+    uint16_t idx;
+    struct vring_used_elem ring[];
+};
+
+struct vring {
+    unsigned int num;
+
+    struct vring_desc *desc;
+
+    struct vring_avail *avail;
+
+    struct vring_used *used;
+};
+
+/* The standard layout for the ring is a continuous chunk of memory which looks
+ * like this.  We assume num is a power of 2.
+ *
+ * struct vring
+ * {
+ *  // The actual descriptors (16 bytes each)
+ *  struct vring_desc desc[num];
+ *
+ *  // A ring of available descriptor heads with free-running index.
+ *  uint16_t avail_flags;
+ *  uint16_t avail_idx;
+ *  uint16_t available[num];
+ *  uint16_t used_event_idx;
+ *
+ *  // Padding to the next align boundary.
+ *  char pad[];
+ *
+ *  // A ring of used descriptor heads with free-running index.
+ *  uint16_t used_flags;
+ *  uint16_t used_idx;
+ *  struct vring_used_elem used[num];
+ *  uint16_t avail_event_idx;
+ * };
+ */
+/* We publish the used event index at the end of the available ring, and vice
+ * versa. They are at the end for backwards compatibility. */
+#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
+#define vring_avail_event(vr) (*(uint16_t *)&(vr)->used->ring[(vr)->num])
+
+static inline void vring_init(struct vring *vr, unsigned int num, void *p,
+                  unsigned long align)
+{
+    vr->num = num;
+    vr->desc = p;
+    vr->avail = p + num*sizeof(struct vring_desc);
+    vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(uint16_t)
+        + align-1) & ~(align - 1));
+}
+
+static inline unsigned vring_size(unsigned int num, unsigned long align)
+{
+    return ((sizeof(struct vring_desc) * num + sizeof(uint16_t) * (3 + num)
+         + align - 1) & ~(align - 1))
+        + sizeof(uint16_t) * 3 + sizeof(struct vring_used_elem) * num;
+}
+
+/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
+/* Assuming a given event_idx value from the other size, if
+ * we have just incremented index from old to new_idx,
+ * should we trigger an event? */
+static inline int vring_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old)
+{
+    /* Note: Xen has similar logic for notification hold-off
+     * in include/xen/interface/io/ring.h with req_event and req_prod
+     * corresponding to event_idx + 1 and new_idx respectively.
+     * Note also that req_event and req_prod in Xen start at 1,
+     * event indexes in virtio start at 0. */
+    return (uint16_t)(new_idx - event_idx - 1) < (uint16_t)(new_idx - old);
+}
+
+#endif /* _LINUX_VIRTIO_RING_H */