/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ struct vring_desc { /* Address (guest-physical). */ __virtio64 addr; /* Length. */ __virtio32 len; /* The flags as indicated above. */ __virtio16 flags; /* We chain unused descriptors via this, too */ __virtio16 next; }; struct vring_avail { __virtio16 flags; __virtio16 idx; __virtio16 ring[]; }; /* uint32_t is used here for ids for padding reasons. */ struct vring_used_elem { /* Index of start of used descriptor chain. */ __virtio32 id; /* Total length of the descriptor chain which was used (written to) */ __virtio32 len; }; typedef struct vring_used_elem __attribute__((aligned(VRING_USED_ALIGN_SIZE))) vring_used_elem_t; struct vring_used { __virtio16 flags; __virtio16 idx; vring_used_elem_t ring[]; }; /* * The ring element addresses are passed between components with different * alignments assumptions. Thus, we might need to decrease the compiler-selected * alignment, and so must use a typedef to make sure the aligned attribute * actually takes hold: * * https://gcc.gnu.org/onlinedocs//gcc/Common-Type-Attributes.html#Common-Type-Attributes * * When used on a struct, or struct member, the aligned attribute can only * increase the alignment; in order to decrease it, the packed attribute must * be specified as well. When used as part of a typedef, the aligned attribute * can both increase and decrease alignment, and specifying the packed * attribute generates a warning. */ typedef struct vring_desc __attribute__((aligned(VRING_DESC_ALIGN_SIZE))) vring_desc_t; typedef struct vring_avail __attribute__((aligned(VRING_AVAIL_ALIGN_SIZE))) vring_avail_t; typedef struct vring_used __attribute__((aligned(VRING_USED_ALIGN_SIZE))) vring_used_t; struct vring { unsigned int num; vring_desc_t *desc; vring_avail_t *avail; vring_used_t *used; };
vhost_net_start ├─virtio_pci_set_guest_notifiers | └─virtio_pci_set_guest_notifier ├─vhost_net_start_one | ├─vhost_net_start_one | | └─vhost_dev_enable_notifiers | | └─virtio_bus_set_host_notifier | | ├─event_notifier_init | | └─virtio_pci_ioeventfd_assign | └─vhost_dev_start | └─vhost_virtqueue_start | ├─vhost_kernel_set_vring_num | ├─vhost_kernel_set_vring_base把内核vring的三个地址设置和用户态一样 | ├─vhost_kernel_set_vring_endian | ├─vhost_virtqueue_set_addr | | └─vhost_kernel_set_vring_addr | ├─vhost_kernel_set_vring_kick | └─vhost_kernel_set_vring_call └─vhost_set_vring_enable
static inline void vring_init(struct vring *vr, unsigned int num, void *p, unsigned long align) { vr->num = num; vr->desc = p; vr->avail = (struct vring_avail *)((char *)p + num * sizeof(struct vring_desc)); vr->used = (void *)(((uintptr_t)&vr->avail->ring[num] + sizeof(__virtio16) + align-1) & ~(align - 1)); }