xref: /kvmtool/virtio/core.c (revision 39d6af073da0205a2714988fb1ba709a77bbc976)
1*39d6af07SAsias He #include <linux/virtio_ring.h>
2*39d6af07SAsias He #include <stdint.h>
3*39d6af07SAsias He #include <sys/uio.h>
4*39d6af07SAsias He #include "kvm/kvm.h"
5*39d6af07SAsias He #include "kvm/virtio.h"
6*39d6af07SAsias He 
7*39d6af07SAsias He struct vring_used_elem *virt_queue__set_used_elem(struct virt_queue *queue, uint32_t head, uint32_t len)
8*39d6af07SAsias He {
9*39d6af07SAsias He 	struct vring_used_elem *used_elem;
10*39d6af07SAsias He 	used_elem	= &queue->vring.used->ring[queue->vring.used->idx++ % queue->vring.num];
11*39d6af07SAsias He 	used_elem->id	= head;
12*39d6af07SAsias He 	used_elem->len	= len;
13*39d6af07SAsias He 	return used_elem;
14*39d6af07SAsias He }
15*39d6af07SAsias He 
16*39d6af07SAsias He uint16_t virt_queue__get_iov(struct virt_queue *queue, struct iovec iov[], uint16_t *out, uint16_t *in, struct kvm *kvm)
17*39d6af07SAsias He {
18*39d6af07SAsias He 	struct vring_desc *desc;
19*39d6af07SAsias He 	uint16_t head, idx;
20*39d6af07SAsias He 
21*39d6af07SAsias He 	idx = head = virt_queue__pop(queue);
22*39d6af07SAsias He 	*out = *in = 0;
23*39d6af07SAsias He 
24*39d6af07SAsias He 	do {
25*39d6af07SAsias He 		desc				= virt_queue__get_desc(queue, idx);
26*39d6af07SAsias He 		iov[*out + *in].iov_base	= guest_flat_to_host(kvm, desc->addr);
27*39d6af07SAsias He 		iov[*out + *in].iov_len		= desc->len;
28*39d6af07SAsias He 		if (desc->flags & VRING_DESC_F_WRITE)
29*39d6af07SAsias He 			(*in)++;
30*39d6af07SAsias He 		else
31*39d6af07SAsias He 			(*out)++;
32*39d6af07SAsias He 		if (desc->flags & VRING_DESC_F_NEXT)
33*39d6af07SAsias He 			idx = desc->next;
34*39d6af07SAsias He 		else
35*39d6af07SAsias He 			break;
36*39d6af07SAsias He 	} while (1);
37*39d6af07SAsias He 
38*39d6af07SAsias He 	return head;
39*39d6af07SAsias He }
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