u-boot/drivers/virtio/virtio_ring.c

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// 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 <log.h>
#include <malloc.h>
#include <virtio_types.h>
#include <virtio.h>
#include <virtio_ring.h>
#include <linux/bug.h>
#include <linux/compat.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);
}
}