| /*- |
| * Copyright Rusty Russell IBM Corporation 2007. |
| * Copyright 2019 NXP |
| * This header is BSD licensed so anyone can use the definitions to implement |
| * compatible drivers/servers. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of IBM nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * $FreeBSD$ |
| */ |
| |
| #ifndef VIRTIO_RING_H |
| #define VIRTIO_RING_H |
| |
| /* This marks a buffer as continuing via the next field. */ |
| #define VRING_DESC_F_NEXT 1U |
| /* This marks a buffer as write-only (otherwise read-only). */ |
| #define VRING_DESC_F_WRITE 2U |
| /* This means the buffer contains a list of buffer descriptors. */ |
| #define VRING_DESC_F_INDIRECT 4U |
| |
| /* The Host uses this in used->flags to advise the Guest: don't kick me |
| * when you add a buffer. It's unreliable, so it's simply an |
| * optimization. Guest will still kick if it's out of buffers. */ |
| #define VRING_USED_F_NO_NOTIFY 1U |
| /* The Guest uses this in avail->flags to advise the Host: don't |
| * interrupt me when you consume a buffer. It's unreliable, so it's |
| * simply an optimization. */ |
| #define VRING_AVAIL_F_NO_INTERRUPT 1U |
| |
| /* VirtIO ring descriptors: 16 bytes. |
| * These can chain together via "next". */ |
| struct vring_desc |
| { |
| /* Address (guest-physical). */ |
| uint64_t addr; |
| /* Length. */ |
| uint32_t len; |
| /* The flags as indicated above. */ |
| uint16_t flags; |
| /* We chain unused descriptors via this, too. */ |
| uint16_t next; |
| }; |
| |
| struct vring_avail |
| { |
| uint16_t flags; |
| uint16_t idx; |
| uint16_t ring[1]; |
| }; |
| |
| /* uint32_t is used here for ids for padding reasons. */ |
| struct vring_used_elem |
| { |
| /* Index of start of used descriptor chain. */ |
| uint32_t id; |
| /* Total length of the descriptor chain which was written to. */ |
| uint32_t len; |
| }; |
| |
| struct vring_used |
| { |
| uint16_t flags; |
| uint16_t idx; |
| struct vring_used_elem ring[1]; |
| }; |
| |
| struct vring |
| { |
| uint32_t num; |
| |
| struct vring_desc *desc; |
| struct vring_avail *avail; |
| struct vring_used *used; |
| }; |
| |
| /* The standard layout for the ring is a continuous chunk of memory which |
| * looks like this. We assume num is a power of 2. |
| * |
| * struct vring { |
| * # The actual descriptors (16 bytes each) |
| * struct vring_desc desc[num]; |
| * |
| * # A ring of available descriptor heads with free-running index. |
| * __u16 avail_flags; |
| * __u16 avail_idx; |
| * __u16 available[num]; |
| * __u16 used_event_idx; |
| * |
| * # Padding to the next align boundary. |
| * char pad[]; |
| * |
| * # A ring of used descriptor heads with free-running index. |
| * __u16 used_flags; |
| * __u16 used_idx; |
| * struct vring_used_elem used[num]; |
| * __u16 avail_event_idx; |
| * }; |
| * |
| * NOTE: for VirtIO PCI, align is 4096. |
| */ |
| |
| /* |
| * We publish the used event index at the end of the available ring, and vice |
| * versa. They are at the end for backwards compatibility. |
| */ |
| #define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) |
| #define vring_avail_event(vr) ((vr)->used->ring[(vr)->num].id) |
| |
| static inline int32_t vring_size(uint32_t num, uint32_t align) |
| { |
| uint32_t size; |
| |
| size = num * sizeof(struct vring_desc); |
| size += sizeof(struct vring_avail) + (num * sizeof(uint16_t)) + sizeof(uint16_t); |
| size = (size + align - 1UL) & ~(align - 1UL); |
| size += sizeof(struct vring_used) + (num * sizeof(struct vring_used_elem)) + sizeof(uint16_t); |
| return ((int32_t)size); |
| } |
| |
| static inline void vring_init(struct vring *vr, uint32_t num, uint8_t *p, uint32_t align) |
| { |
| vr->num = num; |
| vr->desc = (struct vring_desc *)(void *)p; |
| vr->avail = (struct vring_avail *)(void *)(p + num * sizeof(struct vring_desc)); |
| vr->used = (struct vring_used *)(((uint32_t)&vr->avail->ring[num] + align - 1UL) & ~(align - 1UL)); |
| } |
| |
| /* |
| * The following is used with VIRTIO_RING_F_EVENT_IDX. |
| * |
| * Assuming a given event_idx value from the other size, if we have |
| * just incremented index from old to new_idx, should we trigger an |
| * event? |
| */ |
| static inline int32_t vring_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old) |
| { |
| if ((uint16_t)(new_idx - event_idx - 1U) < (uint16_t)(new_idx - old)) |
| { |
| return 1; |
| } |
| else |
| { |
| return 0; |
| } |
| } |
| #endif /* VIRTIO_RING_H */ |