virtio: Add codes for virtual queue/ring management
This adds support for managing virtual queue/ring, the channel
for high performance I/O between host and guest.
Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 23e7be7..17d264a 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -3,4 +3,4 @@
# Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
-obj-y += virtio-uclass.o
+obj-y += virtio-uclass.o virtio_ring.o
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
new file mode 100644
index 0000000..0eeb350
--- /dev/null
+++ b/drivers/virtio/virtio_ring.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * virtio ring implementation
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <malloc.h>
+#include <virtio_types.h>
+#include <virtio.h>
+#include <virtio_ring.h>
+
+int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
+ unsigned int out_sgs, unsigned int in_sgs)
+{
+ struct vring_desc *desc;
+ unsigned int total_sg = out_sgs + in_sgs;
+ unsigned int i, n, avail, descs_used, uninitialized_var(prev);
+ int head;
+
+ WARN_ON(total_sg == 0);
+
+ head = vq->free_head;
+
+ desc = vq->vring.desc;
+ i = head;
+ descs_used = total_sg;
+
+ if (vq->num_free < descs_used) {
+ debug("Can't add buf len %i - avail = %i\n",
+ descs_used, vq->num_free);
+ /*
+ * FIXME: for historical reasons, we force a notify here if
+ * there are outgoing parts to the buffer. Presumably the
+ * host should service the ring ASAP.
+ */
+ if (out_sgs)
+ virtio_notify(vq->vdev, vq);
+ return -ENOSPC;
+ }
+
+ for (n = 0; n < out_sgs; n++) {
+ struct virtio_sg *sg = sgs[n];
+
+ desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
+ desc[i].addr = cpu_to_virtio64(vq->vdev, (u64)(size_t)sg->addr);
+ desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
+
+ prev = i;
+ i = virtio16_to_cpu(vq->vdev, desc[i].next);
+ }
+ for (; n < (out_sgs + in_sgs); n++) {
+ struct virtio_sg *sg = sgs[n];
+
+ desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
+ VRING_DESC_F_WRITE);
+ desc[i].addr = cpu_to_virtio64(vq->vdev,
+ (u64)(uintptr_t)sg->addr);
+ desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
+
+ prev = i;
+ i = virtio16_to_cpu(vq->vdev, desc[i].next);
+ }
+ /* Last one doesn't continue */
+ desc[prev].flags &= cpu_to_virtio16(vq->vdev, ~VRING_DESC_F_NEXT);
+
+ /* We're using some buffers from the free list. */
+ vq->num_free -= descs_used;
+
+ /* Update free pointer */
+ vq->free_head = i;
+
+ /*
+ * Put entry in available array (but don't update avail->idx
+ * until they do sync).
+ */
+ avail = vq->avail_idx_shadow & (vq->vring.num - 1);
+ vq->vring.avail->ring[avail] = cpu_to_virtio16(vq->vdev, head);
+
+ /*
+ * Descriptors and available array need to be set before we expose the
+ * new available array entries.
+ */
+ virtio_wmb();
+ vq->avail_idx_shadow++;
+ vq->vring.avail->idx = cpu_to_virtio16(vq->vdev, vq->avail_idx_shadow);
+ vq->num_added++;
+
+ /*
+ * This is very unlikely, but theoretically possible.
+ * Kick just in case.
+ */
+ if (unlikely(vq->num_added == (1 << 16) - 1))
+ virtqueue_kick(vq);
+
+ return 0;
+}
+
+static bool virtqueue_kick_prepare(struct virtqueue *vq)
+{
+ u16 new, old;
+ bool needs_kick;
+
+ /*
+ * We need to expose available array entries before checking
+ * avail event.
+ */
+ virtio_mb();
+
+ old = vq->avail_idx_shadow - vq->num_added;
+ new = vq->avail_idx_shadow;
+ vq->num_added = 0;
+
+ if (vq->event) {
+ needs_kick = vring_need_event(virtio16_to_cpu(vq->vdev,
+ vring_avail_event(&vq->vring)), new, old);
+ } else {
+ needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(vq->vdev,
+ VRING_USED_F_NO_NOTIFY));
+ }
+
+ return needs_kick;
+}
+
+void virtqueue_kick(struct virtqueue *vq)
+{
+ if (virtqueue_kick_prepare(vq))
+ virtio_notify(vq->vdev, vq);
+}
+
+static void detach_buf(struct virtqueue *vq, unsigned int head)
+{
+ unsigned int i;
+ __virtio16 nextflag = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
+
+ /* Put back on free list: unmap first-level descriptors and find end */
+ i = head;
+
+ while (vq->vring.desc[i].flags & nextflag) {
+ i = virtio16_to_cpu(vq->vdev, vq->vring.desc[i].next);
+ vq->num_free++;
+ }
+
+ vq->vring.desc[i].next = cpu_to_virtio16(vq->vdev, vq->free_head);
+ vq->free_head = head;
+
+ /* Plus final descriptor */
+ vq->num_free++;
+}
+
+static inline bool more_used(const struct virtqueue *vq)
+{
+ return vq->last_used_idx != virtio16_to_cpu(vq->vdev,
+ vq->vring.used->idx);
+}
+
+void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
+{
+ unsigned int i;
+ u16 last_used;
+
+ if (!more_used(vq)) {
+ debug("(%s.%d): No more buffers in queue\n",
+ vq->vdev->name, vq->index);
+ return NULL;
+ }
+
+ /* Only get used array entries after they have been exposed by host */
+ virtio_rmb();
+
+ last_used = (vq->last_used_idx & (vq->vring.num - 1));
+ i = virtio32_to_cpu(vq->vdev, vq->vring.used->ring[last_used].id);
+ if (len) {
+ *len = virtio32_to_cpu(vq->vdev,
+ vq->vring.used->ring[last_used].len);
+ debug("(%s.%d): last used idx %u with len %u\n",
+ vq->vdev->name, vq->index, i, *len);
+ }
+
+ if (unlikely(i >= vq->vring.num)) {
+ printf("(%s.%d): id %u out of range\n",
+ vq->vdev->name, vq->index, i);
+ return NULL;
+ }
+
+ detach_buf(vq, i);
+ vq->last_used_idx++;
+ /*
+ * If we expect an interrupt for the next entry, tell host
+ * by writing event index and flush out the write before
+ * the read in the next get_buf call.
+ */
+ if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+ virtio_store_mb(&vring_used_event(&vq->vring),
+ cpu_to_virtio16(vq->vdev, vq->last_used_idx));
+
+ return (void *)(uintptr_t)virtio64_to_cpu(vq->vdev,
+ vq->vring.desc[i].addr);
+}
+
+static struct virtqueue *__vring_new_virtqueue(unsigned int index,
+ struct vring vring,
+ struct udevice *udev)
+{
+ unsigned int i;
+ struct virtqueue *vq;
+ struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+ struct udevice *vdev = uc_priv->vdev;
+
+ vq = malloc(sizeof(*vq));
+ if (!vq)
+ return NULL;
+
+ vq->vdev = vdev;
+ vq->index = index;
+ vq->num_free = vring.num;
+ vq->vring = vring;
+ vq->last_used_idx = 0;
+ vq->avail_flags_shadow = 0;
+ vq->avail_idx_shadow = 0;
+ vq->num_added = 0;
+ list_add_tail(&vq->list, &uc_priv->vqs);
+
+ vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
+ /* Tell other side not to bother us */
+ vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+ if (!vq->event)
+ vq->vring.avail->flags = cpu_to_virtio16(vdev,
+ vq->avail_flags_shadow);
+
+ /* Put everything in free lists */
+ vq->free_head = 0;
+ for (i = 0; i < vring.num - 1; i++)
+ vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
+
+ return vq;
+}
+
+struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
+ unsigned int vring_align,
+ struct udevice *udev)
+{
+ struct virtqueue *vq;
+ void *queue = NULL;
+ struct vring vring;
+
+ /* We assume num is a power of 2 */
+ if (num & (num - 1)) {
+ printf("Bad virtqueue length %u\n", num);
+ return NULL;
+ }
+
+ /* TODO: allocate each queue chunk individually */
+ for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
+ queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
+ if (queue)
+ break;
+ }
+
+ if (!num)
+ return NULL;
+
+ if (!queue) {
+ /* Try to get a single page. You are my only hope! */
+ queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
+ }
+ if (!queue)
+ return NULL;
+
+ memset(queue, 0, vring_size(num, vring_align));
+ vring_init(&vring, num, queue, vring_align);
+
+ vq = __vring_new_virtqueue(index, vring, udev);
+ if (!vq) {
+ free(queue);
+ return NULL;
+ }
+ debug("(%s): created vring @ %p for vq @ %p with num %u\n", udev->name,
+ queue, vq, num);
+
+ return vq;
+}
+
+void vring_del_virtqueue(struct virtqueue *vq)
+{
+ free(vq->vring.desc);
+ list_del(&vq->list);
+ free(vq);
+}
+
+unsigned int virtqueue_get_vring_size(struct virtqueue *vq)
+{
+ return vq->vring.num;
+}
+
+ulong virtqueue_get_desc_addr(struct virtqueue *vq)
+{
+ return (ulong)vq->vring.desc;
+}
+
+ulong virtqueue_get_avail_addr(struct virtqueue *vq)
+{
+ return (ulong)vq->vring.desc +
+ ((char *)vq->vring.avail - (char *)vq->vring.desc);
+}
+
+ulong virtqueue_get_used_addr(struct virtqueue *vq)
+{
+ return (ulong)vq->vring.desc +
+ ((char *)vq->vring.used - (char *)vq->vring.desc);
+}
+
+bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx)
+{
+ virtio_mb();
+
+ return last_used_idx != virtio16_to_cpu(vq->vdev, vq->vring.used->idx);
+}
+
+void virtqueue_dump(struct virtqueue *vq)
+{
+ unsigned int i;
+
+ printf("virtqueue %p for dev %s:\n", vq, vq->vdev->name);
+ printf("\tindex %u, phys addr %p num %u\n",
+ vq->index, vq->vring.desc, vq->vring.num);
+ printf("\tfree_head %u, num_added %u, num_free %u\n",
+ vq->free_head, vq->num_added, vq->num_free);
+ printf("\tlast_used_idx %u, avail_flags_shadow %u, avail_idx_shadow %u\n",
+ vq->last_used_idx, vq->avail_flags_shadow, vq->avail_idx_shadow);
+
+ printf("Descriptor dump:\n");
+ for (i = 0; i < vq->vring.num; i++) {
+ printf("\tdesc[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
+ i, vq->vring.desc[i].addr, vq->vring.desc[i].len,
+ vq->vring.desc[i].flags, vq->vring.desc[i].next);
+ }
+
+ printf("Avail ring dump:\n");
+ printf("\tflags %u, idx %u\n",
+ vq->vring.avail->flags, vq->vring.avail->idx);
+ for (i = 0; i < vq->vring.num; i++) {
+ printf("\tavail[%u] = %u\n",
+ i, vq->vring.avail->ring[i]);
+ }
+
+ printf("Used ring dump:\n");
+ printf("\tflags %u, idx %u\n",
+ vq->vring.used->flags, vq->vring.used->idx);
+ for (i = 0; i < vq->vring.num; i++) {
+ printf("\tused[%u] = { %u, %u }\n", i,
+ vq->vring.used->ring[i].id, vq->vring.used->ring[i].len);
+ }
+}