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virtio.c
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virtio.c
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/*
* VIRTIO
*/
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include "virtio.h"
#include "address_space.h"
static inline uint16_t
vring_avail_idx(vqueue_t *vq)
{
vring_t *vring = (vring_t *)vq;
uint64_t pa = vring->avail + offsetof(vring_avail_t, idx);
return (uint16_t)as_read_nommu(NULL, pa, 2, 0);
}
static bool
virtio_queue_empty(vqueue_t *vq)
{
return vring_avail_idx(vq) == vq->last_avail_idx;
}
static inline uint16_t
vring_avail_ring(vqueue_t *vq, int i)
{
vring_t *vring = (vring_t *)vq;
uint64_t pa = vring->avail + offsetof(vring_avail_t, ring[i]);
return (uint16_t)as_read_nommu(NULL, pa, 2, 0);
}
static int
vqueue_get_head(vqueue_t *vq, uint32_t idx, uint32_t *head)
{
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
*head = vring_avail_ring(vq, (int)(idx % vq->vring.num));
/* If their number is silly, that's a fatal mistake. */
if (*head >= vq->vring.num)
panic("bad index %u\n", *head);
return 0;
}
static void
vring_desc_read(vqueue_t *vq, uint32_t idx, vring_desc_t *desc)
{
vring_t *vring = (vring_t *)vq;
uint64_t pa = vring->desc + idx * sizeof(vring_desc_t);
as_read_blob(pa, sizeof(vring_desc_t), (uint8_t *)desc);
}
vq_request_t *
vring_desc_read_indirect(uint32_t head, uint64_t addr, uint32_t len)
{
uint64_t offset = 0;
uint32_t iov_num = 0;
uint32_t in_len = 0;
iovec_t iov[VIRTQUEUE_MAX_SIZE];
vring_desc_t desc;
vq_request_t *req;
if ((len == 0) || (len % sizeof(vring_desc_t)))
panic("bad size %u for indirect table\n", len);
while (1) {
as_read_blob(addr + offset, sizeof(vring_desc_t), (uint8_t *)&desc);
iov[iov_num].base = desc.addr;
iov[iov_num].len = desc.len;
if (desc.flags & VRING_DESC_F_WRITE) {
iov[iov_num].flags = IO_VEC_F_WRITE;
in_len += desc.len;
} else {
iov[iov_num].flags = IO_VEC_F_READ;
}
iov_num++;
if (!(desc.flags & VRING_DESC_F_NEXT))
break;
offset = desc.next * sizeof(vring_desc_t);
}
req = malloc(sizeof(vq_request_t));
req->index = head;
req->in_len = in_len;
req->num = iov_num;
req->iov = malloc(iov_num * sizeof(iovec_t));
memcpy(req->iov, iov, iov_num * sizeof(iovec_t));
return req;
}
static inline bool
virtio_has_feature(uint64_t features, uint32_t fbit)
{
return !!(features & fbit);
}
static inline bool
virtio_dev_has_feature(virtio_dev_t *vdev, uint32_t fbit)
{
return virtio_has_feature(vdev->guest_features, fbit);
}
static inline void
vring_set_avail_event(vqueue_t *vq, uint16_t val)
{
vring_t *vring = (vring_t *)vq;
uint64_t pa = vring->used + offsetof(vring_used_t, ring[vq->vring.num]);
as_write_nommu(NULL, pa, 2, val, 0);
}
vq_request_t *
vqueue_pop(virtio_dev_t *vdev, vqueue_t *vq)
{
uint32_t head;
vring_desc_t desc;
if (virtio_queue_empty(vq))
return NULL;
if (vqueue_get_head(vq, vq->last_avail_idx++, &head) < 0)
return NULL;
if (virtio_dev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX))
vring_set_avail_event(vq, vq->last_avail_idx);
vring_desc_read(vq, head, &desc);
if (desc.flags & VRING_DESC_F_INDIRECT) {
return vring_desc_read_indirect(head, desc.addr, desc.len);
} else {
panic("%s: now only support indirect desc table!\n", __func__);
}
printf("%s: desc addr(0x%lx) len(%u) flags(0x%x) next(%u)\n",
__func__, desc.addr, desc.len, desc.flags, desc.next);
return NULL;
}
void
vring_init(vring_t *vring, uint64_t pfn, uint32_t page_shift)
{
vring->desc = pfn << page_shift;
if (!vring->num || !vring->desc || !vring->align) {
panic("%s: not yet setup\n", __func__);
}
vring->avail = vring->desc + vring->num * sizeof(vring_desc_t);
vring->used = vring_align(vring->avail +
offsetof(vring_avail_t, ring[vring->num]),
vring->align);
}
static void
vring_used_idx_set(vqueue_t *vq, uint16_t val)
{
vring_t *vring = (vring_t *)vq;
uint64_t pa = vring->used + offsetof(vring_used_t, idx);
as_write_nommu(NULL, pa, 2, val, 0);
}
void
vring_used_write(vqueue_t *vq, vq_request_t *req)
{
vring_t *vring = (vring_t *)vq;
uint32_t idx = vq->used_idx % vring->num;
uint64_t pa = vring->used + offsetof(vring_used_t, ring[idx]);
as_write_nommu(NULL, pa, 4, req->index, 0);
as_write_nommu(NULL, pa + 4, 4, req->in_len, 0);
vq->used_idx++;
vring_used_idx_set(vq, vq->used_idx);
}