mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 20:02:17 +00:00
![Ricardo Cañuelo](/assets/img/avatar_default.png)
Fix variable names in some kerneldocs, naming in others. Add kerneldocs for struct vring_desc and vring_interrupt. Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com> Message-Id: <20220810094004.1250-2-ricardo.canuelo@collabora.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
250 lines
8.5 KiB
C
250 lines
8.5 KiB
C
#ifndef _UAPI_LINUX_VIRTIO_RING_H
|
|
#define _UAPI_LINUX_VIRTIO_RING_H
|
|
/* An interface for efficient virtio implementation, currently for use by KVM,
|
|
* but hopefully others soon. Do NOT change this since it will
|
|
* break existing servers and clients.
|
|
*
|
|
* 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.
|
|
*
|
|
* Copyright Rusty Russell IBM Corporation 2007. */
|
|
#ifndef __KERNEL__
|
|
#include <stdint.h>
|
|
#endif
|
|
#include <linux/types.h>
|
|
#include <linux/virtio_types.h>
|
|
|
|
/* This marks a buffer as continuing via the next field. */
|
|
#define VRING_DESC_F_NEXT 1
|
|
/* This marks a buffer as write-only (otherwise read-only). */
|
|
#define VRING_DESC_F_WRITE 2
|
|
/* This means the buffer contains a list of buffer descriptors. */
|
|
#define VRING_DESC_F_INDIRECT 4
|
|
|
|
/*
|
|
* Mark a descriptor as available or used in packed ring.
|
|
* Notice: they are defined as shifts instead of shifted values.
|
|
*/
|
|
#define VRING_PACKED_DESC_F_AVAIL 7
|
|
#define VRING_PACKED_DESC_F_USED 15
|
|
|
|
/* 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 1
|
|
/* 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 1
|
|
|
|
/* Enable events in packed ring. */
|
|
#define VRING_PACKED_EVENT_FLAG_ENABLE 0x0
|
|
/* Disable events in packed ring. */
|
|
#define VRING_PACKED_EVENT_FLAG_DISABLE 0x1
|
|
/*
|
|
* Enable events for a specific descriptor in packed ring.
|
|
* (as specified by Descriptor Ring Change Event Offset/Wrap Counter).
|
|
* Only valid if VIRTIO_RING_F_EVENT_IDX has been negotiated.
|
|
*/
|
|
#define VRING_PACKED_EVENT_FLAG_DESC 0x2
|
|
|
|
/*
|
|
* Wrap counter bit shift in event suppression structure
|
|
* of packed ring.
|
|
*/
|
|
#define VRING_PACKED_EVENT_F_WRAP_CTR 15
|
|
|
|
/* We support indirect buffer descriptors */
|
|
#define VIRTIO_RING_F_INDIRECT_DESC 28
|
|
|
|
/* The Guest publishes the used index for which it expects an interrupt
|
|
* at the end of the avail ring. Host should ignore the avail->flags field. */
|
|
/* The Host publishes the avail index for which it expects a kick
|
|
* at the end of the used ring. Guest should ignore the used->flags field. */
|
|
#define VIRTIO_RING_F_EVENT_IDX 29
|
|
|
|
/* Alignment requirements for vring elements.
|
|
* When using pre-virtio 1.0 layout, these fall out naturally.
|
|
*/
|
|
#define VRING_AVAIL_ALIGN_SIZE 2
|
|
#define VRING_USED_ALIGN_SIZE 4
|
|
#define VRING_DESC_ALIGN_SIZE 16
|
|
|
|
/**
|
|
* struct vring_desc - Virtio ring descriptors,
|
|
* 16 bytes long. These can chain together via @next.
|
|
*
|
|
* @addr: buffer address (guest-physical)
|
|
* @len: buffer length
|
|
* @flags: descriptor flags
|
|
* @next: index of the next descriptor in the chain,
|
|
* if the VRING_DESC_F_NEXT flag is set. We chain unused
|
|
* descriptors via this, too.
|
|
*/
|
|
struct vring_desc {
|
|
__virtio64 addr;
|
|
__virtio32 len;
|
|
__virtio16 flags;
|
|
__virtio16 next;
|
|
};
|
|
|
|
struct vring_avail {
|
|
__virtio16 flags;
|
|
__virtio16 idx;
|
|
__virtio16 ring[];
|
|
};
|
|
|
|
/* u32 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;
|
|
};
|
|
|
|
#ifndef VIRTIO_RING_NO_LEGACY
|
|
|
|
/* 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.
|
|
* __virtio16 avail_flags;
|
|
* __virtio16 avail_idx;
|
|
* __virtio16 available[num];
|
|
* __virtio16 used_event_idx;
|
|
*
|
|
* // Padding to the next align boundary.
|
|
* char pad[];
|
|
*
|
|
* // A ring of used descriptor heads with free-running index.
|
|
* __virtio16 used_flags;
|
|
* __virtio16 used_idx;
|
|
* struct vring_used_elem used[num];
|
|
* __virtio16 avail_event_idx;
|
|
* };
|
|
*/
|
|
/* 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) (*(__virtio16 *)&(vr)->used->ring[(vr)->num])
|
|
|
|
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));
|
|
}
|
|
|
|
static inline unsigned vring_size(unsigned int num, unsigned long align)
|
|
{
|
|
return ((sizeof(struct vring_desc) * num + sizeof(__virtio16) * (3 + num)
|
|
+ align - 1) & ~(align - 1))
|
|
+ sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num;
|
|
}
|
|
|
|
#endif /* VIRTIO_RING_NO_LEGACY */
|
|
|
|
/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
|
|
/* Assuming a given event_idx value from the other side, if
|
|
* we have just incremented index from old to new_idx,
|
|
* should we trigger an event? */
|
|
static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
|
|
{
|
|
/* Note: Xen has similar logic for notification hold-off
|
|
* in include/xen/interface/io/ring.h with req_event and req_prod
|
|
* corresponding to event_idx + 1 and new_idx respectively.
|
|
* Note also that req_event and req_prod in Xen start at 1,
|
|
* event indexes in virtio start at 0. */
|
|
return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
|
|
}
|
|
|
|
struct vring_packed_desc_event {
|
|
/* Descriptor Ring Change Event Offset/Wrap Counter. */
|
|
__le16 off_wrap;
|
|
/* Descriptor Ring Change Event Flags. */
|
|
__le16 flags;
|
|
};
|
|
|
|
struct vring_packed_desc {
|
|
/* Buffer Address. */
|
|
__le64 addr;
|
|
/* Buffer Length. */
|
|
__le32 len;
|
|
/* Buffer ID. */
|
|
__le16 id;
|
|
/* The flags depending on descriptor type. */
|
|
__le16 flags;
|
|
};
|
|
|
|
#endif /* _UAPI_LINUX_VIRTIO_RING_H */
|