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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>
This commit is contained in:
Tuomas Tynkkynen
committed by
Simon Glass
Simon Glass
parent
8fb49b4c7a
commit
c011641ec4
358
drivers/virtio/virtio_ring.c
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358
drivers/virtio/virtio_ring.c
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// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
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* Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
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*
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* virtio ring implementation
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*/
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#include <common.h>
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#include <dm.h>
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#include <malloc.h>
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#include <virtio_types.h>
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#include <virtio.h>
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#include <virtio_ring.h>
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int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
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unsigned int out_sgs, unsigned int in_sgs)
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{
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struct vring_desc *desc;
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unsigned int total_sg = out_sgs + in_sgs;
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unsigned int i, n, avail, descs_used, uninitialized_var(prev);
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int head;
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WARN_ON(total_sg == 0);
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head = vq->free_head;
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desc = vq->vring.desc;
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i = head;
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descs_used = total_sg;
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if (vq->num_free < descs_used) {
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debug("Can't add buf len %i - avail = %i\n",
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descs_used, vq->num_free);
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/*
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* FIXME: for historical reasons, we force a notify here if
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* there are outgoing parts to the buffer. Presumably the
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* host should service the ring ASAP.
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*/
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if (out_sgs)
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virtio_notify(vq->vdev, vq);
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return -ENOSPC;
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}
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for (n = 0; n < out_sgs; n++) {
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struct virtio_sg *sg = sgs[n];
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desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
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desc[i].addr = cpu_to_virtio64(vq->vdev, (u64)(size_t)sg->addr);
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desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
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prev = i;
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i = virtio16_to_cpu(vq->vdev, desc[i].next);
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}
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for (; n < (out_sgs + in_sgs); n++) {
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struct virtio_sg *sg = sgs[n];
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desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
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VRING_DESC_F_WRITE);
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desc[i].addr = cpu_to_virtio64(vq->vdev,
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(u64)(uintptr_t)sg->addr);
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desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
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prev = i;
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i = virtio16_to_cpu(vq->vdev, desc[i].next);
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}
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/* Last one doesn't continue */
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desc[prev].flags &= cpu_to_virtio16(vq->vdev, ~VRING_DESC_F_NEXT);
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/* We're using some buffers from the free list. */
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vq->num_free -= descs_used;
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/* Update free pointer */
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vq->free_head = i;
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/*
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* Put entry in available array (but don't update avail->idx
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* until they do sync).
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*/
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avail = vq->avail_idx_shadow & (vq->vring.num - 1);
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vq->vring.avail->ring[avail] = cpu_to_virtio16(vq->vdev, head);
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/*
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* Descriptors and available array need to be set before we expose the
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* new available array entries.
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*/
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virtio_wmb();
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vq->avail_idx_shadow++;
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vq->vring.avail->idx = cpu_to_virtio16(vq->vdev, vq->avail_idx_shadow);
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vq->num_added++;
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/*
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* This is very unlikely, but theoretically possible.
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* Kick just in case.
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*/
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if (unlikely(vq->num_added == (1 << 16) - 1))
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virtqueue_kick(vq);
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return 0;
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}
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static bool virtqueue_kick_prepare(struct virtqueue *vq)
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{
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u16 new, old;
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bool needs_kick;
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/*
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* We need to expose available array entries before checking
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* avail event.
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*/
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virtio_mb();
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old = vq->avail_idx_shadow - vq->num_added;
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new = vq->avail_idx_shadow;
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vq->num_added = 0;
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if (vq->event) {
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needs_kick = vring_need_event(virtio16_to_cpu(vq->vdev,
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vring_avail_event(&vq->vring)), new, old);
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} else {
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needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(vq->vdev,
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VRING_USED_F_NO_NOTIFY));
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}
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return needs_kick;
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}
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void virtqueue_kick(struct virtqueue *vq)
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{
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if (virtqueue_kick_prepare(vq))
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virtio_notify(vq->vdev, vq);
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}
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static void detach_buf(struct virtqueue *vq, unsigned int head)
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{
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unsigned int i;
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__virtio16 nextflag = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
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/* Put back on free list: unmap first-level descriptors and find end */
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i = head;
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while (vq->vring.desc[i].flags & nextflag) {
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i = virtio16_to_cpu(vq->vdev, vq->vring.desc[i].next);
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vq->num_free++;
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}
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vq->vring.desc[i].next = cpu_to_virtio16(vq->vdev, vq->free_head);
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vq->free_head = head;
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/* Plus final descriptor */
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vq->num_free++;
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}
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static inline bool more_used(const struct virtqueue *vq)
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{
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return vq->last_used_idx != virtio16_to_cpu(vq->vdev,
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vq->vring.used->idx);
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}
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void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
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{
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unsigned int i;
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u16 last_used;
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if (!more_used(vq)) {
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debug("(%s.%d): No more buffers in queue\n",
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vq->vdev->name, vq->index);
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return NULL;
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}
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/* Only get used array entries after they have been exposed by host */
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virtio_rmb();
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last_used = (vq->last_used_idx & (vq->vring.num - 1));
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i = virtio32_to_cpu(vq->vdev, vq->vring.used->ring[last_used].id);
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if (len) {
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*len = virtio32_to_cpu(vq->vdev,
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vq->vring.used->ring[last_used].len);
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debug("(%s.%d): last used idx %u with len %u\n",
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vq->vdev->name, vq->index, i, *len);
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}
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if (unlikely(i >= vq->vring.num)) {
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printf("(%s.%d): id %u out of range\n",
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vq->vdev->name, vq->index, i);
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return NULL;
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}
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detach_buf(vq, i);
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vq->last_used_idx++;
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/*
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* If we expect an interrupt for the next entry, tell host
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* by writing event index and flush out the write before
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* the read in the next get_buf call.
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*/
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if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
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virtio_store_mb(&vring_used_event(&vq->vring),
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cpu_to_virtio16(vq->vdev, vq->last_used_idx));
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return (void *)(uintptr_t)virtio64_to_cpu(vq->vdev,
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vq->vring.desc[i].addr);
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}
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static struct virtqueue *__vring_new_virtqueue(unsigned int index,
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struct vring vring,
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struct udevice *udev)
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{
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unsigned int i;
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struct virtqueue *vq;
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struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
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struct udevice *vdev = uc_priv->vdev;
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vq = malloc(sizeof(*vq));
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if (!vq)
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return NULL;
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vq->vdev = vdev;
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vq->index = index;
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vq->num_free = vring.num;
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vq->vring = vring;
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vq->last_used_idx = 0;
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vq->avail_flags_shadow = 0;
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vq->avail_idx_shadow = 0;
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vq->num_added = 0;
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list_add_tail(&vq->list, &uc_priv->vqs);
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vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
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/* Tell other side not to bother us */
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vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
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if (!vq->event)
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vq->vring.avail->flags = cpu_to_virtio16(vdev,
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vq->avail_flags_shadow);
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/* Put everything in free lists */
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vq->free_head = 0;
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for (i = 0; i < vring.num - 1; i++)
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vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
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return vq;
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}
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struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
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unsigned int vring_align,
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struct udevice *udev)
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{
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struct virtqueue *vq;
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void *queue = NULL;
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struct vring vring;
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/* We assume num is a power of 2 */
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if (num & (num - 1)) {
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printf("Bad virtqueue length %u\n", num);
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return NULL;
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}
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/* TODO: allocate each queue chunk individually */
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for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
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queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
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if (queue)
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break;
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}
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if (!num)
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return NULL;
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if (!queue) {
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/* Try to get a single page. You are my only hope! */
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queue = memalign(PAGE_SIZE, vring_size(num, vring_align));
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}
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if (!queue)
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return NULL;
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memset(queue, 0, vring_size(num, vring_align));
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vring_init(&vring, num, queue, vring_align);
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vq = __vring_new_virtqueue(index, vring, udev);
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if (!vq) {
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free(queue);
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return NULL;
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}
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debug("(%s): created vring @ %p for vq @ %p with num %u\n", udev->name,
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queue, vq, num);
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return vq;
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}
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void vring_del_virtqueue(struct virtqueue *vq)
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{
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free(vq->vring.desc);
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list_del(&vq->list);
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free(vq);
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}
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unsigned int virtqueue_get_vring_size(struct virtqueue *vq)
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{
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return vq->vring.num;
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}
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ulong virtqueue_get_desc_addr(struct virtqueue *vq)
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{
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return (ulong)vq->vring.desc;
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}
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ulong virtqueue_get_avail_addr(struct virtqueue *vq)
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{
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return (ulong)vq->vring.desc +
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((char *)vq->vring.avail - (char *)vq->vring.desc);
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}
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ulong virtqueue_get_used_addr(struct virtqueue *vq)
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{
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return (ulong)vq->vring.desc +
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((char *)vq->vring.used - (char *)vq->vring.desc);
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}
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bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx)
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{
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virtio_mb();
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return last_used_idx != virtio16_to_cpu(vq->vdev, vq->vring.used->idx);
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}
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void virtqueue_dump(struct virtqueue *vq)
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{
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unsigned int i;
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printf("virtqueue %p for dev %s:\n", vq, vq->vdev->name);
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printf("\tindex %u, phys addr %p num %u\n",
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vq->index, vq->vring.desc, vq->vring.num);
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printf("\tfree_head %u, num_added %u, num_free %u\n",
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vq->free_head, vq->num_added, vq->num_free);
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printf("\tlast_used_idx %u, avail_flags_shadow %u, avail_idx_shadow %u\n",
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vq->last_used_idx, vq->avail_flags_shadow, vq->avail_idx_shadow);
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printf("Descriptor dump:\n");
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for (i = 0; i < vq->vring.num; i++) {
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printf("\tdesc[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
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i, vq->vring.desc[i].addr, vq->vring.desc[i].len,
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vq->vring.desc[i].flags, vq->vring.desc[i].next);
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}
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printf("Avail ring dump:\n");
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printf("\tflags %u, idx %u\n",
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vq->vring.avail->flags, vq->vring.avail->idx);
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for (i = 0; i < vq->vring.num; i++) {
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printf("\tavail[%u] = %u\n",
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i, vq->vring.avail->ring[i]);
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}
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printf("Used ring dump:\n");
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printf("\tflags %u, idx %u\n",
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vq->vring.used->flags, vq->vring.used->idx);
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for (i = 0; i < vq->vring.num; i++) {
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printf("\tused[%u] = { %u, %u }\n", i,
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vq->vring.used->ring[i].id, vq->vring.used->ring[i].len);
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}
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}
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