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/* virtio-pci.c - virtio ring management
*
* (c) Copyright 2008 Bull S.A.S.
*
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
* some parts from Linux Virtio Ring
*
* Copyright Rusty Russell IBM Corporation 2007
*
* Adopted for Seabios: Gleb Natapov <gleb@redhat.com>
*
* This work is licensed under the terms of the GNU LGPLv3
* See the COPYING file in the top-level directory.
*
*
*/
#include "output.h" // panic
#include "virtio-ring.h"
#include "virtio-pci.h"
#define BUG() do { \
panic("BUG: failure at %d/%s()!\n", __LINE__, __func__); \
} while (0)
#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
/*
* vring_more_used
*
* is there some used buffers ?
*
*/
int vring_more_used(struct vring_virtqueue *vq)
{
struct vring_used *used = vq->vring.used;
int more = vq->last_used_idx != used->idx;
/* Make sure ring reads are done after idx read above. */
smp_rmb();
return more;
}
/*
* vring_free
*
* put at the begin of the free list the current desc[head]
*/
void vring_detach(struct vring_virtqueue *vq, unsigned int head)
{
struct vring *vr = &vq->vring;
struct vring_desc *desc = GET_LOWFLAT(vr->desc);
unsigned int i;
/* find end of given descriptor */
i = head;
while (desc[i].flags & VRING_DESC_F_NEXT)
i = desc[i].next;
/* link it with free list and point to it */
desc[i].next = vq->free_head;
vq->free_head = head;
}
/*
* vring_get_buf
*
* get a buffer from the used list
*
*/
int vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
{
struct vring *vr = &vq->vring;
struct vring_used_elem *elem;
struct vring_used *used = vq->vring.used;
u32 id;
int ret;
// BUG_ON(!vring_more_used(vq));
elem = &used->ring[vq->last_used_idx % vr->num];
id = elem->id;
if (len != NULL)
*len = elem->len;
ret = vq->vdata[id];
vring_detach(vq, id);
vq->last_used_idx = vq->last_used_idx + 1;
return ret;
}
void vring_add_buf(struct vring_virtqueue *vq,
struct vring_list list[],
unsigned int out, unsigned int in,
int index, int num_added)
{
struct vring *vr = &vq->vring;
int i, av, head, prev;
struct vring_desc *desc = vr->desc;
struct vring_avail *avail = vr->avail;
BUG_ON(out + in == 0);
prev = 0;
head = vq->free_head;
for (i = head; out; i = desc[i].next, out--) {
desc[i].flags = VRING_DESC_F_NEXT;
desc[i].addr = (u64)virt_to_phys(list->addr);
desc[i].len = list->length;
prev = i;
list++;
}
for ( ; in; i = desc[i].next, in--) {
desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
desc[i].addr = (u64)virt_to_phys(list->addr);
desc[i].len = list->length;
prev = i;
list++;
}
desc[prev].flags = desc[prev].flags & ~VRING_DESC_F_NEXT;
vq->free_head = i;
vq->vdata[head] = index;
av = (avail->idx + num_added) % vr->num;
avail->ring[av] = head;
}
void vring_kick(struct vp_device *vp, struct vring_virtqueue *vq, int num_added)
{
struct vring *vr = &vq->vring;
struct vring_avail *avail = vr->avail;
/* Make sure idx update is done after ring write. */
smp_wmb();
avail->idx = avail->idx + num_added;
vp_notify(vp, vq);
}
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