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_iov(struct virt_queue *queue, struct iovec iov[], u16 *out, u16 *in, struct kvm *kvm) 37 { 38 struct vring_desc *desc; 39 u16 head, idx; 40 41 idx = head = virt_queue__pop(queue); 42 *out = *in = 0; 43 44 do { 45 desc = virt_queue__get_desc(queue, 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 /* in and out are relative to guest */ 62 u16 virt_queue__get_inout_iov(struct kvm *kvm, struct virt_queue *queue, 63 struct iovec in_iov[], struct iovec out_iov[], 64 u16 *in, u16 *out) 65 { 66 u16 head, idx; 67 struct vring_desc *desc; 68 69 idx = head = virt_queue__pop(queue); 70 *out = *in = 0; 71 do { 72 desc = virt_queue__get_desc(queue, idx); 73 if (desc->flags & VRING_DESC_F_WRITE) { 74 in_iov[*in].iov_base = guest_flat_to_host(kvm, 75 desc->addr); 76 in_iov[*in].iov_len = desc->len; 77 (*in)++; 78 } else { 79 out_iov[*out].iov_base = guest_flat_to_host(kvm, 80 desc->addr); 81 out_iov[*out].iov_len = desc->len; 82 (*out)++; 83 } 84 if (desc->flags & VRING_DESC_F_NEXT) 85 idx = desc->next; 86 else 87 break; 88 } while (1); 89 return head; 90 } 91 92 int virtio__get_dev_specific_field(int offset, bool msix, bool features_hi, u32 *config_off) 93 { 94 if (msix) { 95 if (offset < 4) 96 return VIRTIO_PCI_O_MSIX; 97 else 98 offset -= 4; 99 } 100 101 if (features_hi) { 102 if (offset < 4) 103 return VIRTIO_PCI_O_FEATURES; 104 else 105 offset -= 4; 106 } 107 108 *config_off = offset; 109 110 return VIRTIO_PCI_O_CONFIG; 111 } 112