[PATCH V2 1/5] vhost: factor out IOTLB

From: Jason Wang
Date: Sun Feb 09 2020 - 22:58:39 EST

This patch factors out IOTLB into a dedicated module in order to be
reused by other modules like vringh. User may choose to enable the
automatic retiring by specifying VHOST_IOTLB_FLAG_RETIRE flag to fit
for the case of vhost device IOTLB implementation.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/vhost/Kconfig | 7 ++
drivers/vhost/Makefile | 2 +
drivers/vhost/net.c | 2 +-
drivers/vhost/vhost.c | 221 +++++++++++-------------------------
drivers/vhost/vhost.h | 36 ++----
drivers/vhost/vhost_iotlb.c | 171 ++++++++++++++++++++++++++++
include/linux/vhost_iotlb.h | 45 ++++++++
8 files changed, 304 insertions(+), 181 deletions(-)
create mode 100644 drivers/vhost/vhost_iotlb.c
create mode 100644 include/linux/vhost_iotlb.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 2549f10eb0b1..d4bda9c900fa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17607,6 +17607,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
S: Maintained
F: drivers/vhost/
F: include/uapi/linux/vhost.h
+F: include/linux/vhost_iotlb.h

VIRTIO INPUT DRIVER
M: Gerd Hoffmann <kraxel@xxxxxxxxxx>
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index 3d03ccbd1adc..eef634ff9a6e 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -36,6 +36,7 @@ config VHOST_VSOCK

config VHOST
tristate
+ select VHOST_IOTLB
---help---
This option is selected by any driver which needs to access
the core of vhost.
@@ -54,3 +55,9 @@ config VHOST_CROSS_ENDIAN_LEGACY
adds some overhead, it is disabled by default.

If unsure, say "N".
+
+config VHOST_IOTLB
+ tristate
+ default m
+ help
+ Generic IOTLB implementation for vhost and vringh.
diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
index 6c6df24f770c..df99756fbb26 100644
--- a/drivers/vhost/Makefile
+++ b/drivers/vhost/Makefile
@@ -11,3 +11,5 @@ vhost_vsock-y := vsock.o
obj-$(CONFIG_VHOST_RING) += vringh.o

obj-$(CONFIG_VHOST) += vhost.o
+
+obj-$(CONFIG_VHOST_IOTLB) += vhost_iotlb.o
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index e158159671fa..e4a20d7a2921 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1594,7 +1594,7 @@ static long vhost_net_reset_owner(struct vhost_net *n)
struct socket *tx_sock = NULL;
struct socket *rx_sock = NULL;
long err;
- struct vhost_umem *umem;
+ struct vhost_iotlb *umem;

mutex_lock(&n->dev.mutex);
err = vhost_dev_check_owner(&n->dev);
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f44340b41494..9059b95cac83 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -50,10 +50,6 @@ enum {
#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])

-INTERVAL_TREE_DEFINE(struct vhost_umem_node,
- rb, __u64, __subtree_last,
- START, LAST, static inline, vhost_umem_interval_tree);
-
#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
{
@@ -581,21 +577,25 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_dev_set_owner);

-struct vhost_umem *vhost_dev_reset_owner_prepare(void)
+static struct vhost_iotlb *iotlb_alloc(void)
+{
+ return vhost_iotlb_alloc(max_iotlb_entries,
+ VHOST_IOTLB_FLAG_RETIRE);
+}
+
+struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
{
- return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
+ return iotlb_alloc();
}
EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);

/* Caller should have device mutex */
-void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
+void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
{
int i;

vhost_dev_cleanup(dev);

- /* Restore memory to default empty mapping. */
- INIT_LIST_HEAD(&umem->umem_list);
dev->umem = umem;
/* We don't need VQ locks below since vhost_dev_cleanup makes sure
* VQs aren't running.
@@ -618,28 +618,6 @@ void vhost_dev_stop(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_dev_stop);

-static void vhost_umem_free(struct vhost_umem *umem,
- struct vhost_umem_node *node)
-{
- vhost_umem_interval_tree_remove(node, &umem->umem_tree);
- list_del(&node->link);
- kfree(node);
- umem->numem--;
-}
-
-static void vhost_umem_clean(struct vhost_umem *umem)
-{
- struct vhost_umem_node *node, *tmp;
-
- if (!umem)
- return;
-
- list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
- vhost_umem_free(umem, node);
-
- kvfree(umem);
-}
-
static void vhost_clear_msg(struct vhost_dev *dev)
{
struct vhost_msg_node *node, *n;
@@ -677,9 +655,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
eventfd_ctx_put(dev->log_ctx);
dev->log_ctx = NULL;
/* No one will access memory at this point */
- vhost_umem_clean(dev->umem);
+ vhost_iotlb_free(dev->umem);
dev->umem = NULL;
- vhost_umem_clean(dev->iotlb);
+ vhost_iotlb_free(dev->iotlb);
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
@@ -715,27 +693,26 @@ static bool vhost_overflow(u64 uaddr, u64 size)
}

/* Caller should have vq mutex and device mutex. */
-static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
+static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
int log_all)
{
- struct vhost_umem_node *node;
+ struct vhost_iotlb_map *map;

if (!umem)
return false;

- list_for_each_entry(node, &umem->umem_list, link) {
- unsigned long a = node->userspace_addr;
+ list_for_each_entry(map, &umem->list, link) {
+ unsigned long a = map->addr;

- if (vhost_overflow(node->userspace_addr, node->size))
+ if (vhost_overflow(map->addr, map->size))
return false;


- if (!access_ok((void __user *)a,
- node->size))
+ if (!access_ok((void __user *)a, map->size))
return false;
else if (log_all && !log_access_ok(log_base,
- node->start,
- node->size))
+ map->start,
+ map->size))
return false;
}
return true;
@@ -745,17 +722,17 @@ static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
u64 addr, unsigned int size,
int type)
{
- const struct vhost_umem_node *node = vq->meta_iotlb[type];
+ const struct vhost_iotlb_map *map = vq->meta_iotlb[type];

- if (!node)
+ if (!map)
return NULL;

- return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
+ return (void *)(uintptr_t)(map->addr + addr - map->start);
}

/* Can we switch to this memory table? */
/* Caller should have device mutex but not vq mutex */
-static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
+static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
int log_all)
{
int i;
@@ -1020,47 +997,6 @@ static inline int vhost_get_desc(struct vhost_virtqueue *vq,
return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
}

-static int vhost_new_umem_range(struct vhost_umem *umem,
- u64 start, u64 size, u64 end,
- u64 userspace_addr, int perm)
-{
- struct vhost_umem_node *tmp, *node;
-
- if (!size)
- return -EFAULT;
-
- node = kmalloc(sizeof(*node), GFP_ATOMIC);
- if (!node)
- return -ENOMEM;
-
- if (umem->numem == max_iotlb_entries) {
- tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
- vhost_umem_free(umem, tmp);
- }
-
- node->start = start;
- node->size = size;
- node->last = end;
- node->userspace_addr = userspace_addr;
- node->perm = perm;
- INIT_LIST_HEAD(&node->link);
- list_add_tail(&node->link, &umem->umem_list);
- vhost_umem_interval_tree_insert(node, &umem->umem_tree);
- umem->numem++;
-
- return 0;
-}
-
-static void vhost_del_umem_range(struct vhost_umem *umem,
- u64 start, u64 end)
-{
- struct vhost_umem_node *node;
-
- while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
- start, end)))
- vhost_umem_free(umem, node);
-}
-
static void vhost_iotlb_notify_vq(struct vhost_dev *d,
struct vhost_iotlb_msg *msg)
{
@@ -1117,9 +1053,9 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
break;
}
vhost_vq_meta_reset(dev);
- if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
- msg->iova + msg->size - 1,
- msg->uaddr, msg->perm)) {
+ if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
+ msg->iova + msg->size - 1,
+ msg->uaddr, msg->perm)) {
ret = -ENOMEM;
break;
}
@@ -1131,8 +1067,8 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
break;
}
vhost_vq_meta_reset(dev);
- vhost_del_umem_range(dev->iotlb, msg->iova,
- msg->iova + msg->size - 1);
+ vhost_iotlb_del_range(dev->iotlb, msg->iova,
+ msg->iova + msg->size - 1);
break;
default:
ret = -EINVAL;
@@ -1311,44 +1247,42 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
}

static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
- const struct vhost_umem_node *node,
+ const struct vhost_iotlb_map *map,
int type)
{
int access = (type == VHOST_ADDR_USED) ?
VHOST_ACCESS_WO : VHOST_ACCESS_RO;

- if (likely(node->perm & access))
- vq->meta_iotlb[type] = node;
+ if (likely(map->perm & access))
+ vq->meta_iotlb[type] = map;
}

static bool iotlb_access_ok(struct vhost_virtqueue *vq,
int access, u64 addr, u64 len, int type)
{
- const struct vhost_umem_node *node;
- struct vhost_umem *umem = vq->iotlb;
+ const struct vhost_iotlb_map *map;
+ struct vhost_iotlb *umem = vq->iotlb;
u64 s = 0, size, orig_addr = addr, last = addr + len - 1;

if (vhost_vq_meta_fetch(vq, addr, len, type))
return true;

while (len > s) {
- node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
- addr,
- last);
- if (node == NULL || node->start > addr) {
+ map = vhost_iotlb_itree_first(umem, addr, last);
+ if (map == NULL || map->start > addr) {
vhost_iotlb_miss(vq, addr, access);
return false;
- } else if (!(node->perm & access)) {
+ } else if (!(map->perm & access)) {
/* Report the possible access violation by
* request another translation from userspace.
*/
return false;
}

- size = node->size - addr + node->start;
+ size = map->size - addr + map->start;

if (orig_addr == addr && size >= len)
- vhost_vq_meta_update(vq, node, type);
+ vhost_vq_meta_update(vq, map, type);

s += size;
addr += size;
@@ -1364,12 +1298,12 @@ int vq_meta_prefetch(struct vhost_virtqueue *vq)
if (!vq->iotlb)
return 1;

- return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
+ return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
- iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
+ iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
vhost_get_avail_size(vq, num),
VHOST_ADDR_AVAIL) &&
- iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
+ iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
vhost_get_used_size(vq, num), VHOST_ADDR_USED);
}
EXPORT_SYMBOL_GPL(vq_meta_prefetch);
@@ -1408,25 +1342,11 @@ bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
}
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);

-static struct vhost_umem *vhost_umem_alloc(void)
-{
- struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
-
- if (!umem)
- return NULL;
-
- umem->umem_tree = RB_ROOT_CACHED;
- umem->numem = 0;
- INIT_LIST_HEAD(&umem->umem_list);
-
- return umem;
-}
-
static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
{
struct vhost_memory mem, *newmem;
struct vhost_memory_region *region;
- struct vhost_umem *newumem, *oldumem;
+ struct vhost_iotlb *newumem, *oldumem;
unsigned long size = offsetof(struct vhost_memory, regions);
int i;

@@ -1448,7 +1368,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
return -EFAULT;
}

- newumem = vhost_umem_alloc();
+ newumem = iotlb_alloc();
if (!newumem) {
kvfree(newmem);
return -ENOMEM;
@@ -1457,13 +1377,12 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
for (region = newmem->regions;
region < newmem->regions + mem.nregions;
region++) {
- if (vhost_new_umem_range(newumem,
- region->guest_phys_addr,
- region->memory_size,
- region->guest_phys_addr +
- region->memory_size - 1,
- region->userspace_addr,
- VHOST_ACCESS_RW))
+ if (vhost_iotlb_add_range(newumem,
+ region->guest_phys_addr,
+ region->guest_phys_addr +
+ region->memory_size - 1,
+ region->userspace_addr,
+ VHOST_MAP_RW))
goto err;
}

@@ -1481,11 +1400,11 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
}

kvfree(newmem);
- vhost_umem_clean(oldumem);
+ vhost_iotlb_free(oldumem);
return 0;

err:
- vhost_umem_clean(newumem);
+ vhost_iotlb_free(newumem);
kvfree(newmem);
return -EFAULT;
}
@@ -1726,10 +1645,10 @@ EXPORT_SYMBOL_GPL(vhost_vring_ioctl);

int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
{
- struct vhost_umem *niotlb, *oiotlb;
+ struct vhost_iotlb *niotlb, *oiotlb;
int i;

- niotlb = vhost_umem_alloc();
+ niotlb = iotlb_alloc();
if (!niotlb)
return -ENOMEM;

@@ -1745,7 +1664,7 @@ int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
mutex_unlock(&vq->mutex);
}

- vhost_umem_clean(oiotlb);
+ vhost_iotlb_free(oiotlb);

return 0;
}
@@ -1875,8 +1794,8 @@ static int log_write(void __user *log_base,

static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
{
- struct vhost_umem *umem = vq->umem;
- struct vhost_umem_node *u;
+ struct vhost_iotlb *umem = vq->umem;
+ struct vhost_iotlb_map *u;
u64 start, end, l, min;
int r;
bool hit = false;
@@ -1886,16 +1805,15 @@ static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
/* More than one GPAs can be mapped into a single HVA. So
* iterate all possible umems here to be safe.
*/
- list_for_each_entry(u, &umem->umem_list, link) {
- if (u->userspace_addr > hva - 1 + len ||
- u->userspace_addr - 1 + u->size < hva)
+ list_for_each_entry(u, &umem->list, link) {
+ if (u->addr > hva - 1 + len ||
+ u->addr - 1 + u->size < hva)
continue;
- start = max(u->userspace_addr, hva);
- end = min(u->userspace_addr - 1 + u->size,
- hva - 1 + len);
+ start = max(u->addr, hva);
+ end = min(u->addr - 1 + u->size, hva - 1 + len);
l = end - start + 1;
r = log_write(vq->log_base,
- u->start + start - u->userspace_addr,
+ u->start + start - u->addr,
l);
if (r < 0)
return r;
@@ -2046,9 +1964,9 @@ EXPORT_SYMBOL_GPL(vhost_vq_init_access);
static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
struct iovec iov[], int iov_size, int access)
{
- const struct vhost_umem_node *node;
+ const struct vhost_iotlb_map *map;
struct vhost_dev *dev = vq->dev;
- struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
+ struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
struct iovec *_iov;
u64 s = 0;
int ret = 0;
@@ -2060,25 +1978,24 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
break;
}

- node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
- addr, addr + len - 1);
- if (node == NULL || node->start > addr) {
+ map = vhost_iotlb_itree_first(umem, addr, addr + len - 1);
+ if (map == NULL || map->start > addr) {
if (umem != dev->iotlb) {
ret = -EFAULT;
break;
}
ret = -EAGAIN;
break;
- } else if (!(node->perm & access)) {
+ } else if (!(map->perm & access)) {
ret = -EPERM;
break;
}

_iov = iov + ret;
- size = node->size - addr + node->start;
+ size = map->size - addr + map->start;
_iov->iov_len = min((u64)len - s, size);
_iov->iov_base = (void __user *)(unsigned long)
- (node->userspace_addr + addr - node->start);
+ (map->addr + addr - map->start);
s += size;
addr += size;
++ret;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index a123fd70847e..b99c6ffb6be1 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -12,6 +12,7 @@
#include <linux/virtio_config.h>
#include <linux/virtio_ring.h>
#include <linux/atomic.h>
+#include <linux/vhost_iotlb.h>

struct vhost_work;
typedef void (*vhost_work_fn_t)(struct vhost_work *work);
@@ -52,27 +53,6 @@ struct vhost_log {
u64 len;
};

-#define START(node) ((node)->start)
-#define LAST(node) ((node)->last)
-
-struct vhost_umem_node {
- struct rb_node rb;
- struct list_head link;
- __u64 start;
- __u64 last;
- __u64 size;
- __u64 userspace_addr;
- __u32 perm;
- __u32 flags_padding;
- __u64 __subtree_last;
-};
-
-struct vhost_umem {
- struct rb_root_cached umem_tree;
- struct list_head umem_list;
- int numem;
-};
-
enum vhost_uaddr_type {
VHOST_ADDR_DESC = 0,
VHOST_ADDR_AVAIL = 1,
@@ -90,7 +70,7 @@ struct vhost_virtqueue {
struct vring_desc __user *desc;
struct vring_avail __user *avail;
struct vring_used __user *used;
- const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS];
+ const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS];
struct file *kick;
struct eventfd_ctx *call_ctx;
struct eventfd_ctx *error_ctx;
@@ -128,8 +108,8 @@ struct vhost_virtqueue {
struct iovec *indirect;
struct vring_used_elem *heads;
/* Protected by virtqueue mutex. */
- struct vhost_umem *umem;
- struct vhost_umem *iotlb;
+ struct vhost_iotlb *umem;
+ struct vhost_iotlb *iotlb;
void *private_data;
u64 acked_features;
u64 acked_backend_features;
@@ -164,8 +144,8 @@ struct vhost_dev {
struct eventfd_ctx *log_ctx;
struct llist_head work_list;
struct task_struct *worker;
- struct vhost_umem *umem;
- struct vhost_umem *iotlb;
+ struct vhost_iotlb *umem;
+ struct vhost_iotlb *iotlb;
spinlock_t iotlb_lock;
struct list_head read_list;
struct list_head pending_list;
@@ -182,8 +162,8 @@ void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
long vhost_dev_set_owner(struct vhost_dev *dev);
bool vhost_dev_has_owner(struct vhost_dev *dev);
long vhost_dev_check_owner(struct vhost_dev *);
-struct vhost_umem *vhost_dev_reset_owner_prepare(void);
-void vhost_dev_reset_owner(struct vhost_dev *, struct vhost_umem *);
+struct vhost_iotlb *vhost_dev_reset_owner_prepare(void);
+void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *iotlb);
void vhost_dev_cleanup(struct vhost_dev *);
void vhost_dev_stop(struct vhost_dev *);
long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
diff --git a/drivers/vhost/vhost_iotlb.c b/drivers/vhost/vhost_iotlb.c
new file mode 100644
index 000000000000..e08710f1690c
--- /dev/null
+++ b/drivers/vhost/vhost_iotlb.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2020 Red Hat, Inc.
+ * Author: Jason Wang <jasowang@xxxxxxxxxx>
+ *
+ * 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@xxxxxxxxxx>"
+#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);
+
+static void 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--;
+}
+
+/**
+ * vhost_iotlb_add_range - 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
+ *
+ * Returns an error last is smaller than start or memory allocation
+ * fails
+ */
+int vhost_iotlb_add_range(struct vhost_iotlb *iotlb,
+ u64 start, u64 last,
+ u64 addr, unsigned int perm)
+{
+ struct vhost_iotlb_map *map;
+
+ if (last < start)
+ return -EFAULT;
+
+ if (iotlb->limit &&
+ iotlb->nmaps == iotlb->limit &&
+ iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) {
+ map = list_first_entry(&iotlb->list, typeof(*map), link);
+ iotlb_map_free(iotlb, map);
+ }
+
+ map = kmalloc(sizeof(*map), GFP_ATOMIC);
+ if (!map)
+ return -ENOMEM;
+
+ map->start = start;
+ map->size = last - start + 1;
+ map->last = last;
+ map->addr = addr;
+ map->perm = perm;
+
+ iotlb->nmaps++;
+ vhost_iotlb_itree_insert(map, &iotlb->root);
+
+ INIT_LIST_HEAD(&map->link);
+ list_add_tail(&map->link, &iotlb->list);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_add_range);
+
+/**
+ * vring_iotlb_del_range - delete overlapped ranges from vhost IOTLB
+ * @iotlb: the IOTLB
+ * @start: start of the IOVA range
+ * @last: last of IOVA range
+ */
+void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last)
+{
+ struct vhost_iotlb_map *map;
+
+ while ((map = vhost_iotlb_itree_iter_first(&iotlb->root,
+ start, last)))
+ iotlb_map_free(iotlb, map);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_del_range);
+
+/**
+ * vhost_iotlb_alloc - add a new vhost IOTLB
+ * @limit: maximum number of IOTLB entries
+ * @flags: VHOST_IOTLB_FLAG_XXX
+ *
+ * Returns an error is memory allocation fails
+ */
+struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags)
+{
+ struct vhost_iotlb *iotlb = kzalloc(sizeof(*iotlb), GFP_KERNEL);
+
+ if (!iotlb)
+ return NULL;
+
+ iotlb->root = RB_ROOT_CACHED;
+ iotlb->limit = limit;
+ iotlb->nmaps = 0;
+ iotlb->flags = flags;
+ INIT_LIST_HEAD(&iotlb->list);
+
+ return iotlb;
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_alloc);
+
+/**
+ * vhost_iotlb_reset - reset vhost IOTLB (free all IOTLB entries)
+ * @iotlb: the IOTLB to be reset
+ */
+void vhost_iotlb_reset(struct vhost_iotlb *iotlb)
+{
+ vhost_iotlb_del_range(iotlb, 0ULL, 0ULL - 1);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_reset);
+
+/**
+ * vhost_iotlb_free - reset and free vhost IOTLB
+ * @iotlb: the IOTLB to be freed
+ */
+void vhost_iotlb_free(struct vhost_iotlb *iotlb)
+{
+ if (iotlb) {
+ vhost_iotlb_reset(iotlb);
+ kfree(iotlb);
+ }
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_free);
+
+/**
+ * vhost_iotlb_itree_first - return the first overlapped range
+ * @iotlb: the IOTLB
+ * @start: start of IOVA range
+ * @end: end of IOVA range
+ */
+struct vhost_iotlb_map *
+vhost_iotlb_itree_first(struct vhost_iotlb *iotlb, u64 start, u64 last)
+{
+ return vhost_iotlb_itree_iter_first(&iotlb->root, start, last);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_itree_first);
+
+/**
+ * vhost_iotlb_itree_first - return the next overlapped range
+ * @iotlb: the IOTLB
+ * @start: start of IOVA range
+ * @end: end of IOVA range
+ */
+struct vhost_iotlb_map *
+vhost_iotlb_itree_next(struct vhost_iotlb_map *map, u64 start, u64 last)
+{
+ return vhost_iotlb_itree_iter_next(map, start, last);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_itree_next);
+
+MODULE_VERSION(MOD_VERSION);
+MODULE_DESCRIPTION(MOD_DESC);
+MODULE_AUTHOR(MOD_AUTHOR);
+MODULE_LICENSE(MOD_LICENSE);
diff --git a/include/linux/vhost_iotlb.h b/include/linux/vhost_iotlb.h
new file mode 100644
index 000000000000..a44c61f5627b
--- /dev/null
+++ b/include/linux/vhost_iotlb.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_VHOST_IOTLB_H
+#define _LINUX_VHOST_IOTLB_H
+
+#include <linux/interval_tree_generic.h>
+
+struct vhost_iotlb_map {
+ struct rb_node rb;
+ struct list_head link;
+ u64 start;
+ u64 last;
+ u64 size;
+ u64 addr;
+#define VHOST_MAP_RO 0x1
+#define VHOST_MAP_WO 0x2
+#define VHOST_MAP_RW 0x3
+ u32 perm;
+ u32 flags_padding;
+ u64 __subtree_last;
+};
+
+#define VHOST_IOTLB_FLAG_RETIRE 0x1
+
+struct vhost_iotlb {
+ struct rb_root_cached root;
+ struct list_head list;
+ unsigned int limit;
+ unsigned int nmaps;
+ unsigned int flags;
+};
+
+int vhost_iotlb_add_range(struct vhost_iotlb *iotlb, u64 start, u64 last,
+ u64 addr, unsigned int perm);
+void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last);
+
+struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags);
+void vhost_iotlb_free(struct vhost_iotlb *iotlb);
+void vhost_iotlb_reset(struct vhost_iotlb *iotlb);
+
+struct vhost_iotlb_map *
+vhost_iotlb_itree_first(struct vhost_iotlb *iotlb, u64 start, u64 last);
+struct vhost_iotlb_map *
+vhost_iotlb_itree_next(struct vhost_iotlb_map *map, u64 start, u64 last);
+
+#endif
--
2.19.1