drivers/vhost/iotlb.c

Source file repositories/reference/linux-study-clean/drivers/vhost/iotlb.c

File Facts

System
Linux kernel
Corpus path
drivers/vhost/iotlb.c
Extension
.c
Size
5384 bytes
Lines
218
Domain
Driver Families
Bucket
drivers/vhost
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2020 Red Hat, Inc.
 * Author: Jason Wang <jasowang@redhat.com>
 *
 * IOTLB implementation for vhost.
 */
#include <linux/slab.h>
#include <linux/vhost_iotlb.h>
#include <linux/module.h>

#define MOD_VERSION  "0.1"
#define MOD_DESC     "VHOST IOTLB"
#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"
#define MOD_LICENSE  "GPL v2"

#define START(map) ((map)->start)
#define LAST(map) ((map)->last)

INTERVAL_TREE_DEFINE(struct vhost_iotlb_map,
		     rb, __u64, __subtree_last,
		     START, LAST, static inline, vhost_iotlb_itree);

/**
 * vhost_iotlb_map_free - remove a map node and free it
 * @iotlb: the IOTLB
 * @map: the map that want to be remove and freed
 */
void vhost_iotlb_map_free(struct vhost_iotlb *iotlb,
			  struct vhost_iotlb_map *map)
{
	vhost_iotlb_itree_remove(map, &iotlb->root);
	list_del(&map->link);
	kfree(map);
	iotlb->nmaps--;
}
EXPORT_SYMBOL_GPL(vhost_iotlb_map_free);

/**
 * vhost_iotlb_add_range_ctx - add a new range to vhost IOTLB
 * @iotlb: the IOTLB
 * @start: start of the IOVA range
 * @last: last of IOVA range
 * @addr: the address that is mapped to @start
 * @perm: access permission of this range
 * @opaque: the opaque pointer for the new mapping
 *
 * Returns an error last is smaller than start or memory allocation
 * fails
 */
int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb,
			      u64 start, u64 last,
			      u64 addr, unsigned int perm,
			      void *opaque)
{
	struct vhost_iotlb_map *map;

	if (last < start)
		return -EFAULT;

	/* If the range being mapped is [0, ULONG_MAX], split it into two entries
	 * otherwise its size would overflow u64.
	 */
	if (start == 0 && last == ULONG_MAX) {
		u64 mid = last / 2;
		int err = vhost_iotlb_add_range_ctx(iotlb, start, mid, addr,
				perm, opaque);

		if (err)
			return err;

		addr += mid + 1;
		start = mid + 1;
	}

	if (iotlb->limit &&
	    iotlb->nmaps == iotlb->limit &&
	    iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) {
		map = list_first_entry(&iotlb->list, typeof(*map), link);
		vhost_iotlb_map_free(iotlb, map);
	}

	map = kmalloc_obj(*map, GFP_ATOMIC);
	if (!map)
		return -ENOMEM;

	map->start = start;
	map->size = last - start + 1;
	map->last = last;
	map->addr = addr;
	map->perm = perm;

Annotation

Implementation Notes