1 files changed, 437 insertions, 0 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
new file mode 100644
index 0000000000..0efe1e0025
--- /dev/null
+++ b/drivers/virtio/virtio_ring.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * virtio ring implementation
+ */
+
+#define pr_fmt(fmt) "virtio_ring: " fmt
+
+#include <common.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_types.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ring.h>
+#include <linux/bug.h>
+#include <dma.h>
+
+#define vq_debug(vq, fmt, ...) \
+	dev_dbg(&vq->vdev->dev, fmt, ##__VA_ARGS__)
+
+#define vq_info(vq, fmt, ...) \
+	dev_info(&vq->vdev->dev, fmt, ##__VA_ARGS__)
+
+static inline struct device *vring_dma_dev(const struct virtqueue *vq)
+{
+	return vq->vdev->dev.parent;
+}
+
+/* Map one sg entry. */
+static dma_addr_t vring_map_one_sg(struct virtqueue *vq,
+				   struct virtio_sg *sg,
+				   enum dma_data_direction direction)
+{
+	return dma_map_single(vring_dma_dev(vq), sg->addr, sg->length, direction);
+}
+
+static int vring_mapping_error(struct virtqueue *vq,
+			       dma_addr_t addr)
+{
+	return dma_mapping_error(vring_dma_dev(vq), addr);
+}
+
+static void vring_unmap_one(struct virtqueue *vq,
+			    struct vring_desc *desc)
+{
+	u16 flags;
+
+	flags = virtio16_to_cpu(vq->vdev, desc->flags);
+
+	dma_unmap_single(vring_dma_dev(vq),
+		       virtio64_to_cpu(vq->vdev, desc->addr),
+		       virtio32_to_cpu(vq->vdev, desc->len),
+		       (flags & VRING_DESC_F_WRITE) ?
+		       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+}
+
+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, err_idx, 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) {
+		vq_debug(vq, "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];
+		dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
+		if (vring_mapping_error(vq, addr))
+			goto unmap_release;
+
+
+		desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
+		desc[i].addr = cpu_to_virtio64(vq->vdev, 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];
+		dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
+		if (vring_mapping_error(vq, addr))
+			goto unmap_release;
+
+		desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
+						VRING_DESC_F_WRITE);
+		desc[i].addr = cpu_to_virtio64(vq->vdev, 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;
+
+unmap_release:
+	err_idx = i;
+
+	for (n = 0; n < total_sg; n++) {
+		if (i == err_idx)
+			break;
+		vring_unmap_one(vq, &desc[i]);
+		i = virtio16_to_cpu(vq->vdev, desc[i].next);
+	}
+
+	return -ENOMEM;
+
+}
+
+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) {
+		vring_unmap_one(vq, &vq->vring.desc[i]);
+		i = virtio16_to_cpu(vq->vdev, vq->vring.desc[i].next);
+		vq->num_free++;
+	}
+
+	vring_unmap_one(vq, &vq->vring.desc[i]);
+	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 virtqueue_poll(vq, vq->last_used_idx);
+}
+
+void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
+{
+	unsigned int i;
+	u16 last_used;
+
+	if (!more_used(vq)) {
+		vq_debug(vq, "No more buffers in queue\n");
+		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);
+		vq_debug(vq, "last used idx %u with len %u\n", i, *len);
+	}
+
+	if (unlikely(i >= vq->vring.num)) {
+		vq_info(vq, "id %u out of range\n", 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 IOMEM((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 virtio_device *vdev)
+{
+	unsigned int i;
+	struct virtqueue *vq;
+
+	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;
+	vq->queue_dma_addr = 0;
+	vq->queue_size_in_bytes = 0;
+	list_add_tail(&vq->list, &vdev->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;
+}
+
+static void *vring_alloc_queue(size_t size, dma_addr_t *dma_handle)
+{
+	return dma_alloc_coherent(size, dma_handle);
+}
+
+static void vring_free_queue(size_t size, void *queue, dma_addr_t dma_handle)
+{
+	dma_free_coherent(queue, dma_handle, size);
+}
+
+struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
+					 unsigned int vring_align,
+					 struct virtio_device *vdev)
+{
+	struct virtqueue *vq;
+	void *queue = NULL;
+	dma_addr_t dma_addr;
+	size_t queue_size_in_bytes;
+	struct vring vring;
+
+	/* We assume num is a power of 2 */
+	if (num & (num - 1)) {
+		pr_err("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 = vring_alloc_queue(vring_size(num, vring_align), &dma_addr);
+		if (queue)
+			break;
+	}
+
+	if (!num)
+		return NULL;
+
+	if (!queue) {
+		/* Try to get a single page. You are my only hope! */
+		queue = vring_alloc_queue(vring_size(num, vring_align), &dma_addr);
+	}
+	if (!queue)
+		return NULL;
+
+	queue_size_in_bytes = vring_size(num, vring_align);
+	vring_init(&vring, num, queue, vring_align);
+
+	vq = __vring_new_virtqueue(index, vring, vdev);
+	if (!vq) {
+		vring_free_queue(queue_size_in_bytes, queue, dma_addr);
+		return NULL;
+	}
+	vq_debug(vq, "created vring @ (virt=%p, phys=%pad) for vq with num %u\n",
+		 queue, &dma_addr, num);
+
+	vq->queue_dma_addr = dma_addr;
+	vq->queue_size_in_bytes = queue_size_in_bytes;
+
+	return vq;
+}
+
+void vring_del_virtqueue(struct virtqueue *vq)
+{
+	vring_free_queue(vq->queue_size_in_bytes, vq->vring.desc, vq->queue_dma_addr);
+	list_del(&vq->list);
+	free(vq);
+}
+
+unsigned int virtqueue_get_vring_size(struct virtqueue *vq)
+{
+	return vq->vring.num;
+}
+
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq)
+{
+	return vq->queue_dma_addr;
+}
+
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq)
+{
+	return vq->queue_dma_addr +
+	       ((char *)vq->vring.avail - (char *)vq->vring.desc);
+}
+
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq)
+{
+	return vq->queue_dma_addr +
+	       ((char *)vq->vring.used - (char *)vq->vring.desc);
+}
+
+bool virtqueue_poll(const 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->dev.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);
+	}
+}
+
+int virtio_notify(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	return vdev->config->notify(vdev, vq);
+}