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
Simon Glass
parent
8fb49b4c7a
commit
c011641ec4
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@ -3,4 +3,4 @@
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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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obj-y += virtio-uclass.o
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obj-y += virtio-uclass.o virtio_ring.o
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@ -0,0 +1,358 @@
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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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@ -0,0 +1,320 @@
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/* SPDX-License-Identifier: BSD-3-Clause */
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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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* From Linux kernel include/uapi/linux/virtio_ring.h
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*/
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#ifndef _LINUX_VIRTIO_RING_H
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#define _LINUX_VIRTIO_RING_H
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#include <virtio_types.h>
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/* This marks a buffer as continuing via the next field */
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#define VRING_DESC_F_NEXT 1
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/* This marks a buffer as write-only (otherwise read-only) */
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#define VRING_DESC_F_WRITE 2
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/* This means the buffer contains a list of buffer descriptors */
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#define VRING_DESC_F_INDIRECT 4
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/*
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* The Host uses this in used->flags to advise the Guest: don't kick me when
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* you add a buffer. It's unreliable, so it's simply an optimization. Guest
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* will still kick if it's out of buffers.
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*/
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#define VRING_USED_F_NO_NOTIFY 1
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/*
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* The Guest uses this in avail->flags to advise the Host: don't interrupt me
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* when you consume a buffer. It's unreliable, so it's simply an optimization.
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*/
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#define VRING_AVAIL_F_NO_INTERRUPT 1
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/* We support indirect buffer descriptors */
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#define VIRTIO_RING_F_INDIRECT_DESC 28
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/*
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* The Guest publishes the used index for which it expects an interrupt
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* at the end of the avail ring. Host should ignore the avail->flags field.
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*
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* The Host publishes the avail index for which it expects a kick
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* at the end of the used ring. Guest should ignore the used->flags field.
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*/
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#define VIRTIO_RING_F_EVENT_IDX 29
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/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
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struct vring_desc {
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/* Address (guest-physical) */
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__virtio64 addr;
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/* Length */
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__virtio32 len;
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/* The flags as indicated above */
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__virtio16 flags;
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/* We chain unused descriptors via this, too */
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__virtio16 next;
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};
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struct vring_avail {
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__virtio16 flags;
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__virtio16 idx;
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__virtio16 ring[];
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};
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struct vring_used_elem {
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/* Index of start of used descriptor chain */
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__virtio32 id;
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/* Total length of the descriptor chain which was used (written to) */
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__virtio32 len;
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};
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struct vring_used {
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__virtio16 flags;
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__virtio16 idx;
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struct vring_used_elem ring[];
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};
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struct vring {
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unsigned int num;
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struct vring_desc *desc;
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struct vring_avail *avail;
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struct vring_used *used;
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};
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/**
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* virtqueue - a queue to register buffers for sending or receiving.
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*
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* @list: the chain of virtqueues for this device
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* @vdev: the virtio device this queue was created for
|
||||
* @index: the zero-based ordinal number for this queue
|
||||
* @num_free: number of elements we expect to be able to fit
|
||||
* @vring: actual memory layout for this queue
|
||||
* @event: host publishes avail event idx
|
||||
* @free_head: head of free buffer list
|
||||
* @num_added: number we've added since last sync
|
||||
* @last_used_idx: last used index we've seen
|
||||
* @avail_flags_shadow: last written value to avail->flags
|
||||
* @avail_idx_shadow: last written value to avail->idx in guest byte order
|
||||
*/
|
||||
struct virtqueue {
|
||||
struct list_head list;
|
||||
struct udevice *vdev;
|
||||
unsigned int index;
|
||||
unsigned int num_free;
|
||||
struct vring vring;
|
||||
bool event;
|
||||
unsigned int free_head;
|
||||
unsigned int num_added;
|
||||
u16 last_used_idx;
|
||||
u16 avail_flags_shadow;
|
||||
u16 avail_idx_shadow;
|
||||
};
|
||||
|
||||
/*
|
||||
* Alignment requirements for vring elements.
|
||||
* When using pre-virtio 1.0 layout, these fall out naturally.
|
||||
*/
|
||||
#define VRING_AVAIL_ALIGN_SIZE 2
|
||||
#define VRING_USED_ALIGN_SIZE 4
|
||||
#define VRING_DESC_ALIGN_SIZE 16
|
||||
|
||||
/*
|
||||
* 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) (*(__virtio16 *)&(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 *)(((uintptr_t)&vr->avail->ring[num] +
|
||||
sizeof(__virtio16) + align - 1) & ~(align - 1));
|
||||
}
|
||||
|
||||
static inline unsigned int vring_size(unsigned int num, unsigned long align)
|
||||
{
|
||||
return ((sizeof(struct vring_desc) * num +
|
||||
sizeof(__virtio16) * (3 + num) + align - 1) & ~(align - 1)) +
|
||||
sizeof(__virtio16) * 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 side, if we have just
|
||||
* incremented index from old to new_idx, should we trigger an event?
|
||||
*/
|
||||
static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 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 (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
|
||||
}
|
||||
|
||||
struct virtio_sg;
|
||||
|
||||
/**
|
||||
* virtqueue_add - expose buffers to other end
|
||||
*
|
||||
* @vq: the struct virtqueue we're talking about
|
||||
* @sgs: array of terminated scatterlists
|
||||
* @out_sgs: the number of scatterlists readable by other side
|
||||
* @in_sgs: the number of scatterlists which are writable
|
||||
* (after readable ones)
|
||||
*
|
||||
* Caller must ensure we don't call this with other virtqueue operations
|
||||
* at the same time (except where noted).
|
||||
*
|
||||
* Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
|
||||
*/
|
||||
int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
|
||||
unsigned int out_sgs, unsigned int in_sgs);
|
||||
|
||||
/**
|
||||
* virtqueue_kick - update after add_buf
|
||||
*
|
||||
* @vq: the struct virtqueue
|
||||
*
|
||||
* After one or more virtqueue_add() calls, invoke this to kick
|
||||
* the other side.
|
||||
*
|
||||
* Caller must ensure we don't call this with other virtqueue
|
||||
* operations at the same time (except where noted).
|
||||
*/
|
||||
void virtqueue_kick(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_get_buf - get the next used buffer
|
||||
*
|
||||
* @vq: the struct virtqueue we're talking about
|
||||
* @len: the length written into the buffer
|
||||
*
|
||||
* If the device wrote data into the buffer, @len will be set to the
|
||||
* amount written. This means you don't need to clear the buffer
|
||||
* beforehand to ensure there's no data leakage in the case of short
|
||||
* writes.
|
||||
*
|
||||
* Caller must ensure we don't call this with other virtqueue
|
||||
* operations at the same time (except where noted).
|
||||
*
|
||||
* Returns NULL if there are no used buffers, or the memory buffer
|
||||
* handed to virtqueue_add_*().
|
||||
*/
|
||||
void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
|
||||
|
||||
/**
|
||||
* vring_create_virtqueue - create a virtqueue for a virtio device
|
||||
*
|
||||
* @index: the index of the queue
|
||||
* @num: number of elements of the queue
|
||||
* @vring_align:the alignment requirement of the descriptor ring
|
||||
* @udev: the virtio transport udevice
|
||||
* @return: the virtqueue pointer or NULL if failed
|
||||
*
|
||||
* This creates a virtqueue and allocates the descriptor ring for a virtio
|
||||
* device. The caller should query virtqueue_get_ring_size() to learn the
|
||||
* actual size of the ring.
|
||||
*
|
||||
* This API is supposed to be called by the virtio transport driver in the
|
||||
* virtio find_vqs() uclass method.
|
||||
*/
|
||||
struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
|
||||
unsigned int vring_align,
|
||||
struct udevice *udev);
|
||||
|
||||
/**
|
||||
* vring_del_virtqueue - destroy a virtqueue
|
||||
*
|
||||
* @vq: the struct virtqueue we're talking about
|
||||
*
|
||||
* This destroys a virtqueue. If created with vring_create_virtqueue(),
|
||||
* this also frees the descriptor ring.
|
||||
*
|
||||
* This API is supposed to be called by the virtio transport driver in the
|
||||
* virtio del_vqs() uclass method.
|
||||
*/
|
||||
void vring_del_virtqueue(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_get_vring_size - get the size of the virtqueue's vring
|
||||
*
|
||||
* @vq: the struct virtqueue containing the vring of interest
|
||||
* @return: the size of the vring in a virtqueue.
|
||||
*/
|
||||
unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_get_desc_addr - get the vring descriptor table address
|
||||
*
|
||||
* @vq: the struct virtqueue containing the vring of interest
|
||||
* @return: the descriptor table address of the vring in a virtqueue.
|
||||
*/
|
||||
ulong virtqueue_get_desc_addr(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_get_avail_addr - get the vring available ring address
|
||||
*
|
||||
* @vq: the struct virtqueue containing the vring of interest
|
||||
* @return: the available ring address of the vring in a virtqueue.
|
||||
*/
|
||||
ulong virtqueue_get_avail_addr(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_get_used_addr - get the vring used ring address
|
||||
*
|
||||
* @vq: the struct virtqueue containing the vring of interest
|
||||
* @return: the used ring address of the vring in a virtqueue.
|
||||
*/
|
||||
ulong virtqueue_get_used_addr(struct virtqueue *vq);
|
||||
|
||||
/**
|
||||
* virtqueue_poll - query pending used buffers
|
||||
*
|
||||
* @vq: the struct virtqueue we're talking about
|
||||
* @last_used_idx: virtqueue last used index
|
||||
*
|
||||
* Returns "true" if there are pending used buffers in the queue.
|
||||
*/
|
||||
bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx);
|
||||
|
||||
/**
|
||||
* virtqueue_dump - dump the virtqueue for debugging
|
||||
*
|
||||
* @vq: the struct virtqueue we're talking about
|
||||
*
|
||||
* Caller must ensure we don't call this with other virtqueue operations
|
||||
* at the same time (except where noted).
|
||||
*/
|
||||
void virtqueue_dump(struct virtqueue *vq);
|
||||
|
||||
/*
|
||||
* Barriers in virtio are tricky. Since we are not in a hyperviosr/guest
|
||||
* scenario, having these as nops is enough to work as expected.
|
||||
*/
|
||||
|
||||
static inline void virtio_mb(void)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void virtio_rmb(void)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void virtio_wmb(void)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void virtio_store_mb(__virtio16 *p, __virtio16 v)
|
||||
{
|
||||
WRITE_ONCE(*p, v);
|
||||
}
|
||||
|
||||
#endif /* _LINUX_VIRTIO_RING_H */
|
||||
Loading…
Reference in New Issue