1 #include <linux/virtio_ring.h> 2 #include <linux/types.h> 3 #include <sys/uio.h> 4 5 #include "kvm/barrier.h" 6 7 #include "kvm/kvm.h" 8 #include "kvm/virtio.h" 9 10 struct vring_used_elem *virt_queue__set_used_elem(struct virt_queue *queue, u32 head, u32 len) 11 { 12 struct vring_used_elem *used_elem; 13 14 used_elem = &queue->vring.used->ring[queue->vring.used->idx % queue->vring.num]; 15 used_elem->id = head; 16 used_elem->len = len; 17 18 /* 19 * Use wmb to assure that used elem was updated with head and len. 20 * We need a wmb here since we can't advance idx unless we're ready 21 * to pass the used element to the guest. 22 */ 23 wmb(); 24 queue->vring.used->idx++; 25 26 /* 27 * Use wmb to assure used idx has been increased before we signal the guest. 28 * Without a wmb here the guest may ignore the queue since it won't see 29 * an updated idx. 30 */ 31 wmb(); 32 33 return used_elem; 34 } 35 36 u16 virt_queue__get_head_iov(struct virt_queue *vq, struct iovec iov[], u16 *out, u16 *in, u16 head, struct kvm *kvm) 37 { 38 struct vring_desc *desc; 39 u16 idx; 40 41 idx = head; 42 *out = *in = 0; 43 44 do { 45 desc = virt_queue__get_desc(vq, idx); 46 iov[*out + *in].iov_base = guest_flat_to_host(kvm, desc->addr); 47 iov[*out + *in].iov_len = desc->len; 48 if (desc->flags & VRING_DESC_F_WRITE) 49 (*in)++; 50 else 51 (*out)++; 52 if (desc->flags & VRING_DESC_F_NEXT) 53 idx = desc->next; 54 else 55 break; 56 } while (1); 57 58 return head; 59 } 60 61 u16 virt_queue__get_iov(struct virt_queue *vq, struct iovec iov[], u16 *out, u16 *in, struct kvm *kvm) 62 { 63 u16 head; 64 65 head = virt_queue__pop(vq); 66 67 return virt_queue__get_head_iov(vq, iov, out, in, head, kvm); 68 } 69 70 /* in and out are relative to guest */ 71 u16 virt_queue__get_inout_iov(struct kvm *kvm, struct virt_queue *queue, 72 struct iovec in_iov[], struct iovec out_iov[], 73 u16 *in, u16 *out) 74 { 75 struct vring_desc *desc; 76 u16 head, idx; 77 78 idx = head = virt_queue__pop(queue); 79 *out = *in = 0; 80 do { 81 desc = virt_queue__get_desc(queue, idx); 82 if (desc->flags & VRING_DESC_F_WRITE) { 83 in_iov[*in].iov_base = guest_flat_to_host(kvm, 84 desc->addr); 85 in_iov[*in].iov_len = desc->len; 86 (*in)++; 87 } else { 88 out_iov[*out].iov_base = guest_flat_to_host(kvm, 89 desc->addr); 90 out_iov[*out].iov_len = desc->len; 91 (*out)++; 92 } 93 if (desc->flags & VRING_DESC_F_NEXT) 94 idx = desc->next; 95 else 96 break; 97 } while (1); 98 99 return head; 100 } 101 102 int virtio__get_dev_specific_field(int offset, bool msix, bool features_hi, u32 *config_off) 103 { 104 if (msix) { 105 if (offset < 4) 106 return VIRTIO_PCI_O_MSIX; 107 else 108 offset -= 4; 109 } 110 111 if (features_hi) { 112 if (offset < 4) 113 return VIRTIO_PCI_O_FEATURES; 114 else 115 offset -= 4; 116 } 117 118 *config_off = offset; 119 120 return VIRTIO_PCI_O_CONFIG; 121 } 122 123 bool virtio_queue__should_signal(struct virt_queue *vq) 124 { 125 u16 old_idx, new_idx, event_idx; 126 127 old_idx = vq->last_used_signalled; 128 new_idx = vq->vring.used->idx; 129 event_idx = vring_used_event(&vq->vring); 130 131 if (vring_need_event(event_idx, new_idx, old_idx)) { 132 vq->last_used_signalled = new_idx; 133 return true; 134 } 135 136 return false; 137 } 138