tools/kvm/virtio/core.c

   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
  93 void virt_queue__trigger_irq(struct virt_queue *vq, int irq, u8 *isr, struct kvm *kvm)
  94 {
  95         if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
  96                 return;
  97
  98         if (*isr == VIRTIO_IRQ_LOW) {
  99                 *isr = VIRTIO_IRQ_HIGH;
 100                 kvm__irq_line(kvm, irq, VIRTIO_IRQ_HIGH);
 101         }
 102 }
 103
 104 int virtio__get_dev_specific_field(int offset, bool msix, bool features_hi, u32 *config_off)
 105 {
 106         if (msix) {
 107                 if (offset < 4)
 108                         return VIRTIO_PCI_O_MSIX;
 109                 else
 110                         offset -= 4;
 111         }
 112
 113         if (features_hi) {
 114                 if (offset < 4)
 115                         return VIRTIO_PCI_O_FEATURES;
 116                 else
 117                         offset -= 4;
 118         }
 119
 120         *config_off = offset;
 121
 122         return VIRTIO_PCI_O_CONFIG;
 123 }