Add support for assigning Address Space Identifiers (ASIDs) to each VQ
group. This enables mapping each group into a distinct memory space.
Now that the driver can change ASID in the middle of operation, the
domain that each vq address point is also protected by domain_lock.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
v8:
* Revert the mutex to rwlock change, it needs proper profiling to
justify it.
v7:
* Take write lock in the error path (Jason).
v6:
* Make vdpa_dev_add use gotos for error handling (MST).
* s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
(MST).
* Fix struct name not matching in the doc.
v5:
* Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
ioctl (Jason).
* Properly set domain bounce size to divide equally between nas (Jason).
* Exclude "padding" member from the only >V1 members in
vduse_dev_request.
v4:
* Divide each domain bounce size between the device bounce size (Jason).
* revert unneeded addr = NULL assignment (Jason)
* Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
return; } (Jason)
* Change a bad multiline comment, using @ caracter instead of * (Jason).
* Consider config->nas == 0 as a fail (Jason).
v3:
* Get the vduse domain through the vduse_as in the map functions
(Jason).
* Squash with the patch creating the vduse_as struct (Jason).
* Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
(Jason)
v2:
* Convert the use of mutex to rwlock.
RFC v3:
* Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
value to reduce memory consumption, but vqs are already limited to
that value and userspace VDUSE is able to allocate that many vqs.
* Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
VDUSE_IOTLB_GET_INFO.
* Use of array_index_nospec in VDUSE device ioctls.
* Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
* Move the umem mutex to asid struct so there is no contention between
ASIDs.
RFC v2:
* Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
part of the struct is the same.
---
drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
include/uapi/linux/vduse.h | 53 ++++-
2 files changed, 292 insertions(+), 109 deletions(-)
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 97be04f73fbf..c6909d73d06d 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -41,6 +41,7 @@
#define VDUSE_DEV_MAX (1U << MINORBITS)
#define VDUSE_DEV_MAX_GROUPS 0xffff
+#define VDUSE_DEV_MAX_AS 0xffff
#define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
#define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
#define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
@@ -86,7 +87,14 @@ struct vduse_umem {
struct mm_struct *mm;
};
+struct vduse_as {
+ struct vduse_iova_domain *domain;
+ struct vduse_umem *umem;
+ struct mutex mem_lock;
+};
+
struct vduse_vq_group {
+ struct vduse_as *as;
struct vduse_dev *dev;
};
@@ -94,7 +102,7 @@ struct vduse_dev {
struct vduse_vdpa *vdev;
struct device *dev;
struct vduse_virtqueue **vqs;
- struct vduse_iova_domain *domain;
+ struct vduse_as *as;
char *name;
struct mutex lock;
spinlock_t msg_lock;
@@ -122,9 +130,8 @@ struct vduse_dev {
u32 vq_num;
u32 vq_align;
u32 ngroups;
- struct vduse_umem *umem;
+ u32 nas;
struct vduse_vq_group *groups;
- struct mutex mem_lock;
unsigned int bounce_size;
struct mutex domain_lock;
};
@@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
return vduse_dev_msg_sync(dev, &msg);
}
-static int vduse_dev_update_iotlb(struct vduse_dev *dev,
+static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
u64 start, u64 last)
{
struct vduse_dev_msg msg = { 0 };
@@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
return -EINVAL;
msg.req.type = VDUSE_UPDATE_IOTLB;
- msg.req.iova.start = start;
- msg.req.iova.last = last;
+ if (dev->api_version < VDUSE_API_VERSION_1) {
+ msg.req.iova.start = start;
+ msg.req.iova.last = last;
+ } else {
+ msg.req.iova_v2.start = start;
+ msg.req.iova_v2.last = last;
+ msg.req.iova_v2.asid = asid;
+ }
return vduse_dev_msg_sync(dev, &msg);
}
@@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
return mask;
}
+/* Force set the asid to a vq group without a message to the VDUSE device */
+static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
+ unsigned int group, unsigned int asid)
+{
+ mutex_lock(&dev->domain_lock);
+ dev->groups[group].as = &dev->as[asid];
+ mutex_unlock(&dev->domain_lock);
+}
+
static void vduse_dev_reset(struct vduse_dev *dev)
{
int i;
- struct vduse_iova_domain *domain = dev->domain;
/* The coherent mappings are handled in vduse_dev_free_coherent() */
- if (domain && domain->bounce_map)
- vduse_domain_reset_bounce_map(domain);
+ for (i = 0; i < dev->nas; i++) {
+ struct vduse_iova_domain *domain = dev->as[i].domain;
+
+ if (domain && domain->bounce_map)
+ vduse_domain_reset_bounce_map(domain);
+ }
+
+ for (i = 0; i < dev->ngroups; i++)
+ vduse_set_group_asid_nomsg(dev, i, 0);
down_write(&dev->rwsem);
@@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
return ret;
}
+static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
+ unsigned int asid)
+{
+ struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+ struct vduse_dev_msg msg = { 0 };
+ int r;
+
+ if (dev->api_version < VDUSE_API_VERSION_1 ||
+ group >= dev->ngroups || asid >= dev->nas)
+ return -EINVAL;
+
+ msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
+ msg.req.vq_group_asid.group = group;
+ msg.req.vq_group_asid.asid = asid;
+
+ r = vduse_dev_msg_sync(dev, &msg);
+ if (r < 0)
+ return r;
+
+ vduse_set_group_asid_nomsg(dev, group, asid);
+ return 0;
+}
+
static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
struct vdpa_vq_state *state)
{
@@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
struct vduse_dev *dev = vdpa_to_vduse(vdpa);
int ret;
- ret = vduse_domain_set_map(dev->domain, iotlb);
+ ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
if (ret)
return ret;
- ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
+ ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
if (ret) {
- vduse_domain_clear_map(dev->domain, iotlb);
+ vduse_domain_clear_map(dev->as[asid].domain, iotlb);
return ret;
}
@@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
.get_vq_affinity = vduse_vdpa_get_vq_affinity,
.reset = vduse_vdpa_reset,
.set_map = vduse_vdpa_set_map,
+ .set_group_asid = vduse_set_group_asid,
.get_vq_map = vduse_get_vq_map,
.free = vduse_vdpa_free,
};
@@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
return;
vdev = token.group->dev;
- domain = vdev->domain;
-
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
+ mutex_unlock(&vdev->domain_lock);
}
static void vduse_dev_sync_single_for_cpu(union virtio_map token,
@@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
return;
vdev = token.group->dev;
- domain = vdev->domain;
-
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
+ mutex_unlock(&vdev->domain_lock);
}
static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
@@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
{
struct vduse_dev *vdev;
struct vduse_iova_domain *domain;
+ dma_addr_t r;
if (!token.group)
return DMA_MAPPING_ERROR;
vdev = token.group->dev;
- domain = vdev->domain;
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
+ r = vduse_domain_map_page(domain, page, offset, size, dir, attrs);
+ mutex_unlock(&vdev->domain_lock);
- return vduse_domain_map_page(domain, page, offset, size, dir, attrs);
+ return r;
}
static void vduse_dev_unmap_page(union virtio_map token, dma_addr_t dma_addr,
@@ -907,9 +965,10 @@ static void vduse_dev_unmap_page(union virtio_map token, dma_addr_t dma_addr,
return;
vdev = token.group->dev;
- domain = vdev->domain;
-
- return vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
+ vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
+ mutex_unlock(&vdev->domain_lock);
}
static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
@@ -925,14 +984,14 @@ static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
return NULL;
vdev = token.group->dev;
- domain = vdev->domain;
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
addr = vduse_domain_alloc_coherent(domain, size,
(dma_addr_t *)&iova, flag);
- if (!addr)
- return NULL;
-
- *dma_addr = (dma_addr_t)iova;
+ if (addr)
+ *dma_addr = (dma_addr_t)iova;
+ mutex_unlock(&vdev->domain_lock);
return addr;
}
@@ -947,23 +1006,28 @@ static void vduse_dev_free_coherent(union virtio_map token, size_t size,
return;
vdev = token.group->dev;
- domain = vdev->domain;
-
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
+ mutex_unlock(&vdev->domain_lock);
}
static bool vduse_dev_need_sync(union virtio_map token, dma_addr_t dma_addr)
{
struct vduse_dev *vdev;
struct vduse_iova_domain *domain;
+ size_t bounce_size;
if (!token.group)
return false;
vdev = token.group->dev;
- domain = vdev->domain;
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
+ bounce_size = domain->bounce_size;
+ mutex_unlock(&vdev->domain_lock);
- return dma_addr < domain->bounce_size;
+ return dma_addr < bounce_size;
}
static int vduse_dev_mapping_error(union virtio_map token, dma_addr_t dma_addr)
@@ -977,14 +1041,18 @@ static size_t vduse_dev_max_mapping_size(union virtio_map token)
{
struct vduse_dev *vdev;
struct vduse_iova_domain *domain;
+ size_t bounce_size;
if (!token.group)
return 0;
vdev = token.group->dev;
- domain = vdev->domain;
+ mutex_lock(&vdev->domain_lock);
+ domain = token.group->as->domain;
+ bounce_size = domain->bounce_size;
+ mutex_unlock(&vdev->domain_lock);
- return domain->bounce_size;
+ return bounce_size;
}
static const struct virtio_map_ops vduse_map_ops = {
@@ -1124,39 +1192,40 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
return ret;
}
-static int vduse_dev_dereg_umem(struct vduse_dev *dev,
+static int vduse_dev_dereg_umem(struct vduse_dev *dev, u32 asid,
u64 iova, u64 size)
{
int ret;
- mutex_lock(&dev->mem_lock);
+ mutex_lock(&dev->as[asid].mem_lock);
ret = -ENOENT;
- if (!dev->umem)
+ if (!dev->as[asid].umem)
goto unlock;
ret = -EINVAL;
- if (!dev->domain)
+ if (!dev->as[asid].domain)
goto unlock;
- if (dev->umem->iova != iova || size != dev->domain->bounce_size)
+ if (dev->as[asid].umem->iova != iova ||
+ size != dev->as[asid].domain->bounce_size)
goto unlock;
- vduse_domain_remove_user_bounce_pages(dev->domain);
- unpin_user_pages_dirty_lock(dev->umem->pages,
- dev->umem->npages, true);
- atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
- mmdrop(dev->umem->mm);
- vfree(dev->umem->pages);
- kfree(dev->umem);
- dev->umem = NULL;
+ vduse_domain_remove_user_bounce_pages(dev->as[asid].domain);
+ unpin_user_pages_dirty_lock(dev->as[asid].umem->pages,
+ dev->as[asid].umem->npages, true);
+ atomic64_sub(dev->as[asid].umem->npages, &dev->as[asid].umem->mm->pinned_vm);
+ mmdrop(dev->as[asid].umem->mm);
+ vfree(dev->as[asid].umem->pages);
+ kfree(dev->as[asid].umem);
+ dev->as[asid].umem = NULL;
ret = 0;
unlock:
- mutex_unlock(&dev->mem_lock);
+ mutex_unlock(&dev->as[asid].mem_lock);
return ret;
}
static int vduse_dev_reg_umem(struct vduse_dev *dev,
- u64 iova, u64 uaddr, u64 size)
+ u32 asid, u64 iova, u64 uaddr, u64 size)
{
struct page **page_list = NULL;
struct vduse_umem *umem = NULL;
@@ -1164,14 +1233,14 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
unsigned long npages, lock_limit;
int ret;
- if (!dev->domain || !dev->domain->bounce_map ||
- size != dev->domain->bounce_size ||
+ if (!dev->as[asid].domain || !dev->as[asid].domain->bounce_map ||
+ size != dev->as[asid].domain->bounce_size ||
iova != 0 || uaddr & ~PAGE_MASK)
return -EINVAL;
- mutex_lock(&dev->mem_lock);
+ mutex_lock(&dev->as[asid].mem_lock);
ret = -EEXIST;
- if (dev->umem)
+ if (dev->as[asid].umem)
goto unlock;
ret = -ENOMEM;
@@ -1195,7 +1264,7 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
goto out;
}
- ret = vduse_domain_add_user_bounce_pages(dev->domain,
+ ret = vduse_domain_add_user_bounce_pages(dev->as[asid].domain,
page_list, pinned);
if (ret)
goto out;
@@ -1208,7 +1277,7 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
umem->mm = current->mm;
mmgrab(current->mm);
- dev->umem = umem;
+ dev->as[asid].umem = umem;
out:
if (ret && pinned > 0)
unpin_user_pages(page_list, pinned);
@@ -1219,7 +1288,7 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
vfree(page_list);
kfree(umem);
}
- mutex_unlock(&dev->mem_lock);
+ mutex_unlock(&dev->as[asid].mem_lock);
return ret;
}
@@ -1251,47 +1320,66 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
switch (cmd) {
case VDUSE_IOTLB_GET_FD: {
- struct vduse_iotlb_entry entry;
+ struct vduse_iotlb_entry_v2 entry;
struct vhost_iotlb_map *map;
struct vdpa_map_file *map_file;
struct file *f = NULL;
+ u32 asid;
ret = -EFAULT;
- if (copy_from_user(&entry, argp, sizeof(entry)))
- break;
+ if (dev->api_version >= VDUSE_API_VERSION_1) {
+ if (copy_from_user(&entry, argp, sizeof(entry)))
+ break;
+ } else {
+ entry.asid = 0;
+ if (copy_from_user(&entry.v1, argp,
+ sizeof(entry.v1)))
+ break;
+ }
ret = -EINVAL;
- if (entry.start > entry.last)
+ if (entry.v1.start > entry.v1.last)
+ break;
+
+ if (entry.asid >= dev->nas)
break;
mutex_lock(&dev->domain_lock);
- if (!dev->domain) {
+ asid = array_index_nospec(entry.asid, dev->nas);
+ if (!dev->as[asid].domain) {
mutex_unlock(&dev->domain_lock);
break;
}
- spin_lock(&dev->domain->iotlb_lock);
- map = vhost_iotlb_itree_first(dev->domain->iotlb,
- entry.start, entry.last);
+ spin_lock(&dev->as[asid].domain->iotlb_lock);
+ map = vhost_iotlb_itree_first(dev->as[asid].domain->iotlb,
+ entry.v1.start, entry.v1.last);
if (map) {
map_file = (struct vdpa_map_file *)map->opaque;
f = get_file(map_file->file);
- entry.offset = map_file->offset;
- entry.start = map->start;
- entry.last = map->last;
- entry.perm = map->perm;
+ entry.v1.offset = map_file->offset;
+ entry.v1.start = map->start;
+ entry.v1.last = map->last;
+ entry.v1.perm = map->perm;
}
- spin_unlock(&dev->domain->iotlb_lock);
+ spin_unlock(&dev->as[asid].domain->iotlb_lock);
mutex_unlock(&dev->domain_lock);
ret = -EINVAL;
if (!f)
break;
- ret = -EFAULT;
- if (copy_to_user(argp, &entry, sizeof(entry))) {
+ if (dev->api_version >= VDUSE_API_VERSION_1)
+ ret = copy_to_user(argp, &entry,
+ sizeof(entry));
+ else
+ ret = copy_to_user(argp, &entry.v1,
+ sizeof(entry.v1));
+
+ if (ret) {
+ ret = -EFAULT;
fput(f);
break;
}
- ret = receive_fd(f, NULL, perm_to_file_flags(entry.perm));
+ ret = receive_fd(f, NULL, perm_to_file_flags(entry.v1.perm));
fput(f);
break;
}
@@ -1436,6 +1524,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
}
case VDUSE_IOTLB_REG_UMEM: {
struct vduse_iova_umem umem;
+ u32 asid;
ret = -EFAULT;
if (copy_from_user(&umem, argp, sizeof(umem)))
@@ -1443,17 +1532,21 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
ret = -EINVAL;
if (!is_mem_zero((const char *)umem.reserved,
- sizeof(umem.reserved)))
+ sizeof(umem.reserved)) ||
+ (dev->api_version < VDUSE_API_VERSION_1 &&
+ umem.asid != 0) || umem.asid >= dev->nas)
break;
mutex_lock(&dev->domain_lock);
- ret = vduse_dev_reg_umem(dev, umem.iova,
+ asid = array_index_nospec(umem.asid, dev->nas);
+ ret = vduse_dev_reg_umem(dev, asid, umem.iova,
umem.uaddr, umem.size);
mutex_unlock(&dev->domain_lock);
break;
}
case VDUSE_IOTLB_DEREG_UMEM: {
struct vduse_iova_umem umem;
+ u32 asid;
ret = -EFAULT;
if (copy_from_user(&umem, argp, sizeof(umem)))
@@ -1461,10 +1554,15 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
ret = -EINVAL;
if (!is_mem_zero((const char *)umem.reserved,
- sizeof(umem.reserved)))
+ sizeof(umem.reserved)) ||
+ (dev->api_version < VDUSE_API_VERSION_1 &&
+ umem.asid != 0) ||
+ umem.asid >= dev->nas)
break;
+
mutex_lock(&dev->domain_lock);
- ret = vduse_dev_dereg_umem(dev, umem.iova,
+ asid = array_index_nospec(umem.asid, dev->nas);
+ ret = vduse_dev_dereg_umem(dev, asid, umem.iova,
umem.size);
mutex_unlock(&dev->domain_lock);
break;
@@ -1472,6 +1570,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
case VDUSE_IOTLB_GET_INFO: {
struct vduse_iova_info info;
struct vhost_iotlb_map *map;
+ u32 asid;
ret = -EFAULT;
if (copy_from_user(&info, argp, sizeof(info)))
@@ -1485,23 +1584,31 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
sizeof(info.reserved)))
break;
+ if (dev->api_version < VDUSE_API_VERSION_1) {
+ if (info.asid)
+ break;
+ } else if (info.asid >= dev->nas)
+ break;
+
mutex_lock(&dev->domain_lock);
- if (!dev->domain) {
+ asid = array_index_nospec(info.asid, dev->nas);
+ if (!dev->as[asid].domain) {
mutex_unlock(&dev->domain_lock);
break;
}
- spin_lock(&dev->domain->iotlb_lock);
- map = vhost_iotlb_itree_first(dev->domain->iotlb,
+ spin_lock(&dev->as[asid].domain->iotlb_lock);
+ map = vhost_iotlb_itree_first(dev->as[asid].domain->iotlb,
info.start, info.last);
if (map) {
info.start = map->start;
info.last = map->last;
info.capability = 0;
- if (dev->domain->bounce_map && map->start == 0 &&
- map->last == dev->domain->bounce_size - 1)
+ if (dev->as[asid].domain->bounce_map &&
+ map->start == 0 &&
+ map->last == dev->as[asid].domain->bounce_size - 1)
info.capability |= VDUSE_IOVA_CAP_UMEM;
}
- spin_unlock(&dev->domain->iotlb_lock);
+ spin_unlock(&dev->as[asid].domain->iotlb_lock);
mutex_unlock(&dev->domain_lock);
if (!map)
break;
@@ -1526,8 +1633,10 @@ static int vduse_dev_release(struct inode *inode, struct file *file)
struct vduse_dev *dev = file->private_data;
mutex_lock(&dev->domain_lock);
- if (dev->domain)
- vduse_dev_dereg_umem(dev, 0, dev->domain->bounce_size);
+ for (int i = 0; i < dev->nas; i++)
+ if (dev->as[i].domain)
+ vduse_dev_dereg_umem(dev, i, 0,
+ dev->as[i].domain->bounce_size);
mutex_unlock(&dev->domain_lock);
spin_lock(&dev->msg_lock);
/* Make sure the inflight messages can processed after reconncection */
@@ -1746,7 +1855,6 @@ static struct vduse_dev *vduse_dev_create(void)
return NULL;
mutex_init(&dev->lock);
- mutex_init(&dev->mem_lock);
mutex_init(&dev->domain_lock);
spin_lock_init(&dev->msg_lock);
INIT_LIST_HEAD(&dev->send_list);
@@ -1797,8 +1905,11 @@ static int vduse_destroy_dev(char *name)
idr_remove(&vduse_idr, dev->minor);
kvfree(dev->config);
vduse_dev_deinit_vqs(dev);
- if (dev->domain)
- vduse_domain_destroy(dev->domain);
+ for (int i = 0; i < dev->nas; i++) {
+ if (dev->as[i].domain)
+ vduse_domain_destroy(dev->as[i].domain);
+ }
+ kfree(dev->as);
kfree(dev->name);
kfree(dev->groups);
vduse_dev_destroy(dev);
@@ -1845,12 +1956,17 @@ static bool vduse_validate_config(struct vduse_dev_config *config,
sizeof(config->reserved)))
return false;
- if (api_version < VDUSE_API_VERSION_1 && config->ngroups)
+ if (api_version < VDUSE_API_VERSION_1 &&
+ (config->ngroups || config->nas))
return false;
- if (api_version >= VDUSE_API_VERSION_1 &&
- (!config->ngroups || config->ngroups > VDUSE_DEV_MAX_GROUPS))
- return false;
+ if (api_version >= VDUSE_API_VERSION_1) {
+ if (!config->ngroups || config->ngroups > VDUSE_DEV_MAX_GROUPS)
+ return false;
+
+ if (!config->nas || config->nas > VDUSE_DEV_MAX_AS)
+ return false;
+ }
if (config->vq_align > PAGE_SIZE)
return false;
@@ -1915,7 +2031,8 @@ static ssize_t bounce_size_store(struct device *device,
ret = -EPERM;
mutex_lock(&dev->domain_lock);
- if (dev->domain)
+ /* Assuming that if the first domain is allocated, all are allocated */
+ if (dev->as[0].domain)
goto unlock;
ret = kstrtouint(buf, 10, &bounce_size);
@@ -1977,6 +2094,13 @@ static int vduse_create_dev(struct vduse_dev_config *config,
for (u32 i = 0; i < dev->ngroups; ++i)
dev->groups[i].dev = dev;
+ dev->nas = (dev->api_version < VDUSE_API_VERSION_1) ? 1 : config->nas;
+ dev->as = kcalloc(dev->nas, sizeof(dev->as[0]), GFP_KERNEL);
+ if (!dev->as)
+ goto err_as;
+ for (int i = 0; i < dev->nas; i++)
+ mutex_init(&dev->as[i].mem_lock);
+
dev->name = kstrdup(config->name, GFP_KERNEL);
if (!dev->name)
goto err_str;
@@ -2013,6 +2137,8 @@ static int vduse_create_dev(struct vduse_dev_config *config,
err_idr:
kfree(dev->name);
err_str:
+ kfree(dev->as);
+err_as:
kfree(dev->groups);
err_vq_groups:
vduse_dev_destroy(dev);
@@ -2138,7 +2264,7 @@ static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev,
&vduse_vdpa_config_ops, &vduse_map_ops,
- dev->ngroups, 1, name, true);
+ dev->ngroups, dev->nas, name, true);
if (IS_ERR(vdev))
return PTR_ERR(vdev);
@@ -2153,7 +2279,8 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
const struct vdpa_dev_set_config *config)
{
struct vduse_dev *dev;
- int ret;
+ size_t domain_bounce_size;
+ int ret, i;
mutex_lock(&vduse_lock);
dev = vduse_find_dev(name);
@@ -2167,29 +2294,38 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
return ret;
mutex_lock(&dev->domain_lock);
- if (!dev->domain)
- dev->domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
- dev->bounce_size);
- mutex_unlock(&dev->domain_lock);
- if (!dev->domain) {
- ret = -ENOMEM;
- goto domain_err;
+ ret = 0;
+
+ domain_bounce_size = dev->bounce_size / dev->nas;
+ for (i = 0; i < dev->nas; ++i) {
+ dev->as[i].domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
+ domain_bounce_size);
+ if (!dev->as[i].domain) {
+ ret = -ENOMEM;
+ goto err;
+ }
}
+ mutex_unlock(&dev->domain_lock);
+
ret = _vdpa_register_device(&dev->vdev->vdpa, dev->vq_num);
- if (ret) {
- goto register_err;
- }
+ if (ret)
+ goto err_register;
return 0;
-register_err:
+err_register:
mutex_lock(&dev->domain_lock);
- vduse_domain_destroy(dev->domain);
- dev->domain = NULL;
+
+err:
+ for (int j = 0; j < i; j++) {
+ if (dev->as[j].domain) {
+ vduse_domain_destroy(dev->as[j].domain);
+ dev->as[j].domain = NULL;
+ }
+ }
mutex_unlock(&dev->domain_lock);
-domain_err:
put_device(&dev->vdev->vdpa.dev);
return ret;
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index a3d51cf6df3a..da2c5e47990e 100644
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h
@@ -47,7 +47,8 @@ struct vduse_dev_config {
__u32 vq_num;
__u32 vq_align;
__u32 ngroups; /* if VDUSE_API_VERSION >= 1 */
- __u32 reserved[12];
+ __u32 nas; /* if VDUSE_API_VERSION >= 1 */
+ __u32 reserved[11];
__u32 config_size;
__u8 config[];
};
@@ -82,6 +83,18 @@ struct vduse_iotlb_entry {
__u8 perm;
};
+/**
+ * struct vduse_iotlb_entry_v2 - entry of IOTLB to describe one IOVA region in an ASID
+ * @v1: the original vduse_iotlb_entry
+ * @asid: address space ID of the IOVA region
+ *
+ * Structure used by VDUSE_IOTLB_GET_FD ioctl to find an overlapped IOVA region.
+ */
+struct vduse_iotlb_entry_v2 {
+ struct vduse_iotlb_entry v1;
+ __u32 asid;
+};
+
/*
* Find the first IOVA region that overlaps with the range [start, last]
* and return the corresponding file descriptor. Return -EINVAL means the
@@ -166,6 +179,16 @@ struct vduse_vq_state_packed {
__u16 last_used_idx;
};
+/**
+ * struct vduse_vq_group_asid - virtqueue group ASID
+ * @group: Index of the virtqueue group
+ * @asid: Address space ID of the group
+ */
+struct vduse_vq_group_asid {
+ __u32 group;
+ __u32 asid;
+};
+
/**
* struct vduse_vq_info - information of a virtqueue
* @index: virtqueue index
@@ -225,6 +248,7 @@ struct vduse_vq_eventfd {
* @uaddr: start address of userspace memory, it must be aligned to page size
* @iova: start of the IOVA region
* @size: size of the IOVA region
+ * @asid: Address space ID of the IOVA region
* @reserved: for future use, needs to be initialized to zero
*
* Structure used by VDUSE_IOTLB_REG_UMEM and VDUSE_IOTLB_DEREG_UMEM
@@ -234,7 +258,8 @@ struct vduse_iova_umem {
__u64 uaddr;
__u64 iova;
__u64 size;
- __u64 reserved[3];
+ __u32 asid;
+ __u32 reserved[5];
};
/* Register userspace memory for IOVA regions */
@@ -248,6 +273,7 @@ struct vduse_iova_umem {
* @start: start of the IOVA region
* @last: last of the IOVA region
* @capability: capability of the IOVA region
+ * @asid: Address space ID of the IOVA region, only if device API version >= 1
* @reserved: for future use, needs to be initialized to zero
*
* Structure used by VDUSE_IOTLB_GET_INFO ioctl to get information of
@@ -258,7 +284,8 @@ struct vduse_iova_info {
__u64 last;
#define VDUSE_IOVA_CAP_UMEM (1 << 0)
__u64 capability;
- __u64 reserved[3];
+ __u32 asid; /* Only if device API version >= 1 */
+ __u32 reserved[5];
};
/*
@@ -280,6 +307,7 @@ enum vduse_req_type {
VDUSE_GET_VQ_STATE,
VDUSE_SET_STATUS,
VDUSE_UPDATE_IOTLB,
+ VDUSE_SET_VQ_GROUP_ASID,
};
/**
@@ -314,6 +342,18 @@ struct vduse_iova_range {
__u64 last;
};
+/**
+ * struct vduse_iova_range - IOVA range [start, last] if API_VERSION >= 1
+ * @start: start of the IOVA range
+ * @last: last of the IOVA range
+ * @asid: address space ID of the IOVA range
+ */
+struct vduse_iova_range_v2 {
+ __u64 start;
+ __u64 last;
+ __u32 asid;
+};
+
/**
* struct vduse_dev_request - control request
* @type: request type
@@ -322,6 +362,8 @@ struct vduse_iova_range {
* @vq_state: virtqueue state, only index field is available
* @s: device status
* @iova: IOVA range for updating
+ * @iova_v2: IOVA range for updating if API_VERSION >= 1
+ * @vq_group_asid: ASID of a virtqueue group
* @padding: padding
*
* Structure used by read(2) on /dev/vduse/$NAME.
@@ -334,6 +376,11 @@ struct vduse_dev_request {
struct vduse_vq_state vq_state;
struct vduse_dev_status s;
struct vduse_iova_range iova;
+ /* Following members but padding exist only if vduse api
+ * version >= 1
+ */;
+ struct vduse_iova_range_v2 iova_v2;
+ struct vduse_vq_group_asid vq_group_asid;
__u32 padding[32];
};
};
--
2.51.0
On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> group. This enables mapping each group into a distinct memory space.
>
> Now that the driver can change ASID in the middle of operation, the
> domain that each vq address point is also protected by domain_lock.
>
> Acked-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
> v8:
> * Revert the mutex to rwlock change, it needs proper profiling to
> justify it.
>
> v7:
> * Take write lock in the error path (Jason).
>
> v6:
> * Make vdpa_dev_add use gotos for error handling (MST).
> * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> (MST).
> * Fix struct name not matching in the doc.
>
> v5:
> * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> ioctl (Jason).
> * Properly set domain bounce size to divide equally between nas (Jason).
> * Exclude "padding" member from the only >V1 members in
> vduse_dev_request.
>
> v4:
> * Divide each domain bounce size between the device bounce size (Jason).
> * revert unneeded addr = NULL assignment (Jason)
> * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> return; } (Jason)
> * Change a bad multiline comment, using @ caracter instead of * (Jason).
> * Consider config->nas == 0 as a fail (Jason).
>
> v3:
> * Get the vduse domain through the vduse_as in the map functions
> (Jason).
> * Squash with the patch creating the vduse_as struct (Jason).
> * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> (Jason)
>
> v2:
> * Convert the use of mutex to rwlock.
>
> RFC v3:
> * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> value to reduce memory consumption, but vqs are already limited to
> that value and userspace VDUSE is able to allocate that many vqs.
> * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> VDUSE_IOTLB_GET_INFO.
> * Use of array_index_nospec in VDUSE device ioctls.
> * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> * Move the umem mutex to asid struct so there is no contention between
> ASIDs.
>
> RFC v2:
> * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> part of the struct is the same.
> ---
> drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> include/uapi/linux/vduse.h | 53 ++++-
> 2 files changed, 292 insertions(+), 109 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 97be04f73fbf..c6909d73d06d 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -41,6 +41,7 @@
>
> #define VDUSE_DEV_MAX (1U << MINORBITS)
> #define VDUSE_DEV_MAX_GROUPS 0xffff
> +#define VDUSE_DEV_MAX_AS 0xffff
> #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> @@ -86,7 +87,14 @@ struct vduse_umem {
> struct mm_struct *mm;
> };
>
> +struct vduse_as {
> + struct vduse_iova_domain *domain;
> + struct vduse_umem *umem;
> + struct mutex mem_lock;
> +};
> +
> struct vduse_vq_group {
> + struct vduse_as *as;
> struct vduse_dev *dev;
> };
>
> @@ -94,7 +102,7 @@ struct vduse_dev {
> struct vduse_vdpa *vdev;
> struct device *dev;
> struct vduse_virtqueue **vqs;
> - struct vduse_iova_domain *domain;
> + struct vduse_as *as;
> char *name;
> struct mutex lock;
> spinlock_t msg_lock;
> @@ -122,9 +130,8 @@ struct vduse_dev {
> u32 vq_num;
> u32 vq_align;
> u32 ngroups;
> - struct vduse_umem *umem;
> + u32 nas;
> struct vduse_vq_group *groups;
> - struct mutex mem_lock;
> unsigned int bounce_size;
> struct mutex domain_lock;
> };
> @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> return vduse_dev_msg_sync(dev, &msg);
> }
>
> -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> u64 start, u64 last)
> {
> struct vduse_dev_msg msg = { 0 };
> @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> return -EINVAL;
>
> msg.req.type = VDUSE_UPDATE_IOTLB;
> - msg.req.iova.start = start;
> - msg.req.iova.last = last;
> + if (dev->api_version < VDUSE_API_VERSION_1) {
> + msg.req.iova.start = start;
> + msg.req.iova.last = last;
> + } else {
> + msg.req.iova_v2.start = start;
> + msg.req.iova_v2.last = last;
> + msg.req.iova_v2.asid = asid;
> + }
>
> return vduse_dev_msg_sync(dev, &msg);
> }
> @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> return mask;
> }
>
> +/* Force set the asid to a vq group without a message to the VDUSE device */
> +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> + unsigned int group, unsigned int asid)
> +{
> + mutex_lock(&dev->domain_lock);
> + dev->groups[group].as = &dev->as[asid];
> + mutex_unlock(&dev->domain_lock);
> +}
> +
> static void vduse_dev_reset(struct vduse_dev *dev)
> {
> int i;
> - struct vduse_iova_domain *domain = dev->domain;
>
> /* The coherent mappings are handled in vduse_dev_free_coherent() */
> - if (domain && domain->bounce_map)
> - vduse_domain_reset_bounce_map(domain);
> + for (i = 0; i < dev->nas; i++) {
> + struct vduse_iova_domain *domain = dev->as[i].domain;
> +
> + if (domain && domain->bounce_map)
> + vduse_domain_reset_bounce_map(domain);
> + }
> +
> + for (i = 0; i < dev->ngroups; i++)
> + vduse_set_group_asid_nomsg(dev, i, 0);
>
> down_write(&dev->rwsem);
>
> @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> return ret;
> }
>
> +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> + unsigned int asid)
> +{
> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> + struct vduse_dev_msg msg = { 0 };
> + int r;
> +
> + if (dev->api_version < VDUSE_API_VERSION_1 ||
> + group >= dev->ngroups || asid >= dev->nas)
> + return -EINVAL;
> +
> + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> + msg.req.vq_group_asid.group = group;
> + msg.req.vq_group_asid.asid = asid;
> +
> + r = vduse_dev_msg_sync(dev, &msg);
> + if (r < 0)
> + return r;
> +
> + vduse_set_group_asid_nomsg(dev, group, asid);
> + return 0;
> +}
> +
> static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> struct vdpa_vq_state *state)
> {
> @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> int ret;
>
> - ret = vduse_domain_set_map(dev->domain, iotlb);
> + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> if (ret)
> return ret;
>
> - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> if (ret) {
> - vduse_domain_clear_map(dev->domain, iotlb);
> + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> return ret;
> }
>
> @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> .reset = vduse_vdpa_reset,
> .set_map = vduse_vdpa_set_map,
> + .set_group_asid = vduse_set_group_asid,
> .get_vq_map = vduse_get_vq_map,
> .free = vduse_vdpa_free,
> };
> @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> return;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> -
> + mutex_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> + mutex_unlock(&vdev->domain_lock);
> }
>
> static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> return;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> -
> + mutex_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> + mutex_unlock(&vdev->domain_lock);
> }
>
> static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> {
> struct vduse_dev *vdev;
> struct vduse_iova_domain *domain;
> + dma_addr_t r;
>
> if (!token.group)
> return DMA_MAPPING_ERROR;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> + mutex_lock(&vdev->domain_lock);
The mutex_lock can't be used here since the dma ops might be called in
atomic context. And I think we can just remove it since creation and
deletion operations of the iova domain are guaranteed not to execute
concurrently with I/O operations.
Thanks,
Yongji
On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
>
> On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > group. This enables mapping each group into a distinct memory space.
> >
> > Now that the driver can change ASID in the middle of operation, the
> > domain that each vq address point is also protected by domain_lock.
> >
> > Acked-by: Jason Wang <jasowang@redhat.com>
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> > v8:
> > * Revert the mutex to rwlock change, it needs proper profiling to
> > justify it.
> >
> > v7:
> > * Take write lock in the error path (Jason).
> >
> > v6:
> > * Make vdpa_dev_add use gotos for error handling (MST).
> > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > (MST).
> > * Fix struct name not matching in the doc.
> >
> > v5:
> > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > ioctl (Jason).
> > * Properly set domain bounce size to divide equally between nas (Jason).
> > * Exclude "padding" member from the only >V1 members in
> > vduse_dev_request.
> >
> > v4:
> > * Divide each domain bounce size between the device bounce size (Jason).
> > * revert unneeded addr = NULL assignment (Jason)
> > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > return; } (Jason)
> > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > * Consider config->nas == 0 as a fail (Jason).
> >
> > v3:
> > * Get the vduse domain through the vduse_as in the map functions
> > (Jason).
> > * Squash with the patch creating the vduse_as struct (Jason).
> > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > (Jason)
> >
> > v2:
> > * Convert the use of mutex to rwlock.
> >
> > RFC v3:
> > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > value to reduce memory consumption, but vqs are already limited to
> > that value and userspace VDUSE is able to allocate that many vqs.
> > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > VDUSE_IOTLB_GET_INFO.
> > * Use of array_index_nospec in VDUSE device ioctls.
> > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > * Move the umem mutex to asid struct so there is no contention between
> > ASIDs.
> >
> > RFC v2:
> > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > part of the struct is the same.
> > ---
> > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > include/uapi/linux/vduse.h | 53 ++++-
> > 2 files changed, 292 insertions(+), 109 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 97be04f73fbf..c6909d73d06d 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -41,6 +41,7 @@
> >
> > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > +#define VDUSE_DEV_MAX_AS 0xffff
> > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > @@ -86,7 +87,14 @@ struct vduse_umem {
> > struct mm_struct *mm;
> > };
> >
> > +struct vduse_as {
> > + struct vduse_iova_domain *domain;
> > + struct vduse_umem *umem;
> > + struct mutex mem_lock;
> > +};
> > +
> > struct vduse_vq_group {
> > + struct vduse_as *as;
> > struct vduse_dev *dev;
> > };
> >
> > @@ -94,7 +102,7 @@ struct vduse_dev {
> > struct vduse_vdpa *vdev;
> > struct device *dev;
> > struct vduse_virtqueue **vqs;
> > - struct vduse_iova_domain *domain;
> > + struct vduse_as *as;
> > char *name;
> > struct mutex lock;
> > spinlock_t msg_lock;
> > @@ -122,9 +130,8 @@ struct vduse_dev {
> > u32 vq_num;
> > u32 vq_align;
> > u32 ngroups;
> > - struct vduse_umem *umem;
> > + u32 nas;
> > struct vduse_vq_group *groups;
> > - struct mutex mem_lock;
> > unsigned int bounce_size;
> > struct mutex domain_lock;
> > };
> > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > return vduse_dev_msg_sync(dev, &msg);
> > }
> >
> > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > u64 start, u64 last)
> > {
> > struct vduse_dev_msg msg = { 0 };
> > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > return -EINVAL;
> >
> > msg.req.type = VDUSE_UPDATE_IOTLB;
> > - msg.req.iova.start = start;
> > - msg.req.iova.last = last;
> > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > + msg.req.iova.start = start;
> > + msg.req.iova.last = last;
> > + } else {
> > + msg.req.iova_v2.start = start;
> > + msg.req.iova_v2.last = last;
> > + msg.req.iova_v2.asid = asid;
> > + }
> >
> > return vduse_dev_msg_sync(dev, &msg);
> > }
> > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > return mask;
> > }
> >
> > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > + unsigned int group, unsigned int asid)
> > +{
> > + mutex_lock(&dev->domain_lock);
> > + dev->groups[group].as = &dev->as[asid];
> > + mutex_unlock(&dev->domain_lock);
> > +}
> > +
> > static void vduse_dev_reset(struct vduse_dev *dev)
> > {
> > int i;
> > - struct vduse_iova_domain *domain = dev->domain;
> >
> > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > - if (domain && domain->bounce_map)
> > - vduse_domain_reset_bounce_map(domain);
> > + for (i = 0; i < dev->nas; i++) {
> > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > +
> > + if (domain && domain->bounce_map)
> > + vduse_domain_reset_bounce_map(domain);
> > + }
> > +
> > + for (i = 0; i < dev->ngroups; i++)
> > + vduse_set_group_asid_nomsg(dev, i, 0);
> >
> > down_write(&dev->rwsem);
> >
> > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > return ret;
> > }
> >
> > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > + unsigned int asid)
> > +{
> > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > + struct vduse_dev_msg msg = { 0 };
> > + int r;
> > +
> > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > + group >= dev->ngroups || asid >= dev->nas)
> > + return -EINVAL;
> > +
> > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > + msg.req.vq_group_asid.group = group;
> > + msg.req.vq_group_asid.asid = asid;
> > +
> > + r = vduse_dev_msg_sync(dev, &msg);
> > + if (r < 0)
> > + return r;
> > +
> > + vduse_set_group_asid_nomsg(dev, group, asid);
> > + return 0;
> > +}
> > +
> > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > struct vdpa_vq_state *state)
> > {
> > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > int ret;
> >
> > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > if (ret)
> > return ret;
> >
> > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > if (ret) {
> > - vduse_domain_clear_map(dev->domain, iotlb);
> > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > return ret;
> > }
> >
> > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > .reset = vduse_vdpa_reset,
> > .set_map = vduse_vdpa_set_map,
> > + .set_group_asid = vduse_set_group_asid,
> > .get_vq_map = vduse_get_vq_map,
> > .free = vduse_vdpa_free,
> > };
> > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > return;
> >
> > vdev = token.group->dev;
> > - domain = vdev->domain;
> > -
> > + mutex_lock(&vdev->domain_lock);
> > + domain = token.group->as->domain;
> > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > + mutex_unlock(&vdev->domain_lock);
> > }
> >
> > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > return;
> >
> > vdev = token.group->dev;
> > - domain = vdev->domain;
> > -
> > + mutex_lock(&vdev->domain_lock);
> > + domain = token.group->as->domain;
> > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > + mutex_unlock(&vdev->domain_lock);
> > }
> >
> > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > {
> > struct vduse_dev *vdev;
> > struct vduse_iova_domain *domain;
> > + dma_addr_t r;
> >
> > if (!token.group)
> > return DMA_MAPPING_ERROR;
> >
> > vdev = token.group->dev;
> > - domain = vdev->domain;
> > + mutex_lock(&vdev->domain_lock);
>
> The mutex_lock can't be used here since the dma ops might be called in
> atomic context. And I think we can just remove it since creation and
> deletion operations of the iova domain are guaranteed not to execute
> concurrently with I/O operations.
>
That would be great indeed! Can you expand on this, what protects here
from the moment the two syscalls are issues from userland?
On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
<eperezma@redhat.com> wrote:
>
> On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > >
> > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > group. This enables mapping each group into a distinct memory space.
> > >
> > > Now that the driver can change ASID in the middle of operation, the
> > > domain that each vq address point is also protected by domain_lock.
> > >
> > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > ---
> > > v8:
> > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > justify it.
> > >
> > > v7:
> > > * Take write lock in the error path (Jason).
> > >
> > > v6:
> > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > (MST).
> > > * Fix struct name not matching in the doc.
> > >
> > > v5:
> > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > ioctl (Jason).
> > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > * Exclude "padding" member from the only >V1 members in
> > > vduse_dev_request.
> > >
> > > v4:
> > > * Divide each domain bounce size between the device bounce size (Jason).
> > > * revert unneeded addr = NULL assignment (Jason)
> > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > return; } (Jason)
> > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > * Consider config->nas == 0 as a fail (Jason).
> > >
> > > v3:
> > > * Get the vduse domain through the vduse_as in the map functions
> > > (Jason).
> > > * Squash with the patch creating the vduse_as struct (Jason).
> > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > (Jason)
> > >
> > > v2:
> > > * Convert the use of mutex to rwlock.
> > >
> > > RFC v3:
> > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > value to reduce memory consumption, but vqs are already limited to
> > > that value and userspace VDUSE is able to allocate that many vqs.
> > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > VDUSE_IOTLB_GET_INFO.
> > > * Use of array_index_nospec in VDUSE device ioctls.
> > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > * Move the umem mutex to asid struct so there is no contention between
> > > ASIDs.
> > >
> > > RFC v2:
> > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > part of the struct is the same.
> > > ---
> > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > include/uapi/linux/vduse.h | 53 ++++-
> > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > index 97be04f73fbf..c6909d73d06d 100644
> > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > @@ -41,6 +41,7 @@
> > >
> > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > struct mm_struct *mm;
> > > };
> > >
> > > +struct vduse_as {
> > > + struct vduse_iova_domain *domain;
> > > + struct vduse_umem *umem;
> > > + struct mutex mem_lock;
> > > +};
> > > +
> > > struct vduse_vq_group {
> > > + struct vduse_as *as;
> > > struct vduse_dev *dev;
> > > };
> > >
> > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > struct vduse_vdpa *vdev;
> > > struct device *dev;
> > > struct vduse_virtqueue **vqs;
> > > - struct vduse_iova_domain *domain;
> > > + struct vduse_as *as;
> > > char *name;
> > > struct mutex lock;
> > > spinlock_t msg_lock;
> > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > u32 vq_num;
> > > u32 vq_align;
> > > u32 ngroups;
> > > - struct vduse_umem *umem;
> > > + u32 nas;
> > > struct vduse_vq_group *groups;
> > > - struct mutex mem_lock;
> > > unsigned int bounce_size;
> > > struct mutex domain_lock;
> > > };
> > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > return vduse_dev_msg_sync(dev, &msg);
> > > }
> > >
> > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > u64 start, u64 last)
> > > {
> > > struct vduse_dev_msg msg = { 0 };
> > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > return -EINVAL;
> > >
> > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > - msg.req.iova.start = start;
> > > - msg.req.iova.last = last;
> > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > + msg.req.iova.start = start;
> > > + msg.req.iova.last = last;
> > > + } else {
> > > + msg.req.iova_v2.start = start;
> > > + msg.req.iova_v2.last = last;
> > > + msg.req.iova_v2.asid = asid;
> > > + }
> > >
> > > return vduse_dev_msg_sync(dev, &msg);
> > > }
> > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > return mask;
> > > }
> > >
> > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > + unsigned int group, unsigned int asid)
> > > +{
> > > + mutex_lock(&dev->domain_lock);
> > > + dev->groups[group].as = &dev->as[asid];
> > > + mutex_unlock(&dev->domain_lock);
> > > +}
> > > +
> > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > {
> > > int i;
> > > - struct vduse_iova_domain *domain = dev->domain;
> > >
> > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > - if (domain && domain->bounce_map)
> > > - vduse_domain_reset_bounce_map(domain);
> > > + for (i = 0; i < dev->nas; i++) {
> > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > +
> > > + if (domain && domain->bounce_map)
> > > + vduse_domain_reset_bounce_map(domain);
> > > + }
> > > +
> > > + for (i = 0; i < dev->ngroups; i++)
> > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > >
> > > down_write(&dev->rwsem);
> > >
> > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > return ret;
> > > }
> > >
> > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > + unsigned int asid)
> > > +{
> > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > + struct vduse_dev_msg msg = { 0 };
> > > + int r;
> > > +
> > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > + group >= dev->ngroups || asid >= dev->nas)
> > > + return -EINVAL;
> > > +
> > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > + msg.req.vq_group_asid.group = group;
> > > + msg.req.vq_group_asid.asid = asid;
> > > +
> > > + r = vduse_dev_msg_sync(dev, &msg);
> > > + if (r < 0)
> > > + return r;
> > > +
> > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > + return 0;
> > > +}
> > > +
> > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > struct vdpa_vq_state *state)
> > > {
> > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > int ret;
> > >
> > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > if (ret)
> > > return ret;
> > >
> > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > if (ret) {
> > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > return ret;
> > > }
> > >
> > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > .reset = vduse_vdpa_reset,
> > > .set_map = vduse_vdpa_set_map,
> > > + .set_group_asid = vduse_set_group_asid,
> > > .get_vq_map = vduse_get_vq_map,
> > > .free = vduse_vdpa_free,
> > > };
> > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > return;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + mutex_lock(&vdev->domain_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > + mutex_unlock(&vdev->domain_lock);
> > > }
> > >
> > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > return;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + mutex_lock(&vdev->domain_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > + mutex_unlock(&vdev->domain_lock);
> > > }
> > >
> > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > {
> > > struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > > + dma_addr_t r;
> > >
> > > if (!token.group)
> > > return DMA_MAPPING_ERROR;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > + mutex_lock(&vdev->domain_lock);
> >
> > The mutex_lock can't be used here since the dma ops might be called in
> > atomic context. And I think we can just remove it since creation and
> > deletion operations of the iova domain are guaranteed not to execute
> > concurrently with I/O operations.
> >
>
> That would be great indeed! Can you expand on this, what protects here
> from the moment the two syscalls are issues from userland?
>
The domain mutex lock is introduced in commit
d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
creation"). It's used to prevent concurrent execution between
vdpa_dev_add() and some vduse device ioctl which needs to access the
iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
would not be called until vdpa_dev_add() completed, so the mutex lock
is not needed.
Thanks,
Yongji
On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
>
> On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> <eperezma@redhat.com> wrote:
> >
> > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > >
> > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > >
> > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > group. This enables mapping each group into a distinct memory space.
> > > >
> > > > Now that the driver can change ASID in the middle of operation, the
> > > > domain that each vq address point is also protected by domain_lock.
> > > >
> > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > ---
> > > > v8:
> > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > justify it.
> > > >
> > > > v7:
> > > > * Take write lock in the error path (Jason).
> > > >
> > > > v6:
> > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > (MST).
> > > > * Fix struct name not matching in the doc.
> > > >
> > > > v5:
> > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > ioctl (Jason).
> > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > * Exclude "padding" member from the only >V1 members in
> > > > vduse_dev_request.
> > > >
> > > > v4:
> > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > * revert unneeded addr = NULL assignment (Jason)
> > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > return; } (Jason)
> > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > * Consider config->nas == 0 as a fail (Jason).
> > > >
> > > > v3:
> > > > * Get the vduse domain through the vduse_as in the map functions
> > > > (Jason).
> > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > (Jason)
> > > >
> > > > v2:
> > > > * Convert the use of mutex to rwlock.
> > > >
> > > > RFC v3:
> > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > value to reduce memory consumption, but vqs are already limited to
> > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > VDUSE_IOTLB_GET_INFO.
> > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > * Move the umem mutex to asid struct so there is no contention between
> > > > ASIDs.
> > > >
> > > > RFC v2:
> > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > part of the struct is the same.
> > > > ---
> > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > >
> > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > @@ -41,6 +41,7 @@
> > > >
> > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > struct mm_struct *mm;
> > > > };
> > > >
> > > > +struct vduse_as {
> > > > + struct vduse_iova_domain *domain;
> > > > + struct vduse_umem *umem;
> > > > + struct mutex mem_lock;
> > > > +};
> > > > +
> > > > struct vduse_vq_group {
> > > > + struct vduse_as *as;
> > > > struct vduse_dev *dev;
> > > > };
> > > >
> > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > struct vduse_vdpa *vdev;
> > > > struct device *dev;
> > > > struct vduse_virtqueue **vqs;
> > > > - struct vduse_iova_domain *domain;
> > > > + struct vduse_as *as;
> > > > char *name;
> > > > struct mutex lock;
> > > > spinlock_t msg_lock;
> > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > u32 vq_num;
> > > > u32 vq_align;
> > > > u32 ngroups;
> > > > - struct vduse_umem *umem;
> > > > + u32 nas;
> > > > struct vduse_vq_group *groups;
> > > > - struct mutex mem_lock;
> > > > unsigned int bounce_size;
> > > > struct mutex domain_lock;
> > > > };
> > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > return vduse_dev_msg_sync(dev, &msg);
> > > > }
> > > >
> > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > u64 start, u64 last)
> > > > {
> > > > struct vduse_dev_msg msg = { 0 };
> > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > return -EINVAL;
> > > >
> > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > - msg.req.iova.start = start;
> > > > - msg.req.iova.last = last;
> > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > + msg.req.iova.start = start;
> > > > + msg.req.iova.last = last;
> > > > + } else {
> > > > + msg.req.iova_v2.start = start;
> > > > + msg.req.iova_v2.last = last;
> > > > + msg.req.iova_v2.asid = asid;
> > > > + }
> > > >
> > > > return vduse_dev_msg_sync(dev, &msg);
> > > > }
> > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > return mask;
> > > > }
> > > >
> > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > + unsigned int group, unsigned int asid)
> > > > +{
> > > > + mutex_lock(&dev->domain_lock);
> > > > + dev->groups[group].as = &dev->as[asid];
> > > > + mutex_unlock(&dev->domain_lock);
> > > > +}
> > > > +
> > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > {
> > > > int i;
> > > > - struct vduse_iova_domain *domain = dev->domain;
> > > >
> > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > - if (domain && domain->bounce_map)
> > > > - vduse_domain_reset_bounce_map(domain);
> > > > + for (i = 0; i < dev->nas; i++) {
> > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > +
> > > > + if (domain && domain->bounce_map)
> > > > + vduse_domain_reset_bounce_map(domain);
> > > > + }
> > > > +
> > > > + for (i = 0; i < dev->ngroups; i++)
> > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > >
> > > > down_write(&dev->rwsem);
> > > >
> > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > return ret;
> > > > }
> > > >
> > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > + unsigned int asid)
> > > > +{
> > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > + struct vduse_dev_msg msg = { 0 };
> > > > + int r;
> > > > +
> > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > + return -EINVAL;
> > > > +
> > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > + msg.req.vq_group_asid.group = group;
> > > > + msg.req.vq_group_asid.asid = asid;
> > > > +
> > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > + if (r < 0)
> > > > + return r;
> > > > +
> > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > + return 0;
> > > > +}
> > > > +
> > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > struct vdpa_vq_state *state)
> > > > {
> > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > int ret;
> > > >
> > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > if (ret)
> > > > return ret;
> > > >
> > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > if (ret) {
> > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > return ret;
> > > > }
> > > >
> > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > .reset = vduse_vdpa_reset,
> > > > .set_map = vduse_vdpa_set_map,
> > > > + .set_group_asid = vduse_set_group_asid,
> > > > .get_vq_map = vduse_get_vq_map,
> > > > .free = vduse_vdpa_free,
> > > > };
> > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > return;
> > > >
> > > > vdev = token.group->dev;
> > > > - domain = vdev->domain;
> > > > -
> > > > + mutex_lock(&vdev->domain_lock);
> > > > + domain = token.group->as->domain;
> > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > + mutex_unlock(&vdev->domain_lock);
> > > > }
> > > >
> > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > return;
> > > >
> > > > vdev = token.group->dev;
> > > > - domain = vdev->domain;
> > > > -
> > > > + mutex_lock(&vdev->domain_lock);
> > > > + domain = token.group->as->domain;
> > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > + mutex_unlock(&vdev->domain_lock);
> > > > }
> > > >
> > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > {
> > > > struct vduse_dev *vdev;
> > > > struct vduse_iova_domain *domain;
> > > > + dma_addr_t r;
> > > >
> > > > if (!token.group)
> > > > return DMA_MAPPING_ERROR;
> > > >
> > > > vdev = token.group->dev;
> > > > - domain = vdev->domain;
> > > > + mutex_lock(&vdev->domain_lock);
> > >
> > > The mutex_lock can't be used here since the dma ops might be called in
> > > atomic context. And I think we can just remove it since creation and
> > > deletion operations of the iova domain are guaranteed not to execute
> > > concurrently with I/O operations.
> > >
> >
> > That would be great indeed! Can you expand on this, what protects here
> > from the moment the two syscalls are issues from userland?
> >
>
> The domain mutex lock is introduced in commit
> d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> creation"). It's used to prevent concurrent execution between
> vdpa_dev_add() and some vduse device ioctl which needs to access the
> iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> would not be called until vdpa_dev_add() completed, so the mutex lock
> is not needed.
>
Yes, but the usage is extended here to also protect from concurrent
calls to vduse_dev_map_page and vduse_set_group_asid or similar.
So I guess the best is to replace it with a spinlock or RCU.
On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
<eperezma@redhat.com> wrote:
>
> On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > <eperezma@redhat.com> wrote:
> > >
> > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > >
> > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > >
> > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > group. This enables mapping each group into a distinct memory space.
> > > > >
> > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > domain that each vq address point is also protected by domain_lock.
> > > > >
> > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > ---
> > > > > v8:
> > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > justify it.
> > > > >
> > > > > v7:
> > > > > * Take write lock in the error path (Jason).
> > > > >
> > > > > v6:
> > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > (MST).
> > > > > * Fix struct name not matching in the doc.
> > > > >
> > > > > v5:
> > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > ioctl (Jason).
> > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > * Exclude "padding" member from the only >V1 members in
> > > > > vduse_dev_request.
> > > > >
> > > > > v4:
> > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > return; } (Jason)
> > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > >
> > > > > v3:
> > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > (Jason).
> > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > (Jason)
> > > > >
> > > > > v2:
> > > > > * Convert the use of mutex to rwlock.
> > > > >
> > > > > RFC v3:
> > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > VDUSE_IOTLB_GET_INFO.
> > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > ASIDs.
> > > > >
> > > > > RFC v2:
> > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > part of the struct is the same.
> > > > > ---
> > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > >
> > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > @@ -41,6 +41,7 @@
> > > > >
> > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > struct mm_struct *mm;
> > > > > };
> > > > >
> > > > > +struct vduse_as {
> > > > > + struct vduse_iova_domain *domain;
> > > > > + struct vduse_umem *umem;
> > > > > + struct mutex mem_lock;
> > > > > +};
> > > > > +
> > > > > struct vduse_vq_group {
> > > > > + struct vduse_as *as;
> > > > > struct vduse_dev *dev;
> > > > > };
> > > > >
> > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > struct vduse_vdpa *vdev;
> > > > > struct device *dev;
> > > > > struct vduse_virtqueue **vqs;
> > > > > - struct vduse_iova_domain *domain;
> > > > > + struct vduse_as *as;
> > > > > char *name;
> > > > > struct mutex lock;
> > > > > spinlock_t msg_lock;
> > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > u32 vq_num;
> > > > > u32 vq_align;
> > > > > u32 ngroups;
> > > > > - struct vduse_umem *umem;
> > > > > + u32 nas;
> > > > > struct vduse_vq_group *groups;
> > > > > - struct mutex mem_lock;
> > > > > unsigned int bounce_size;
> > > > > struct mutex domain_lock;
> > > > > };
> > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > }
> > > > >
> > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > u64 start, u64 last)
> > > > > {
> > > > > struct vduse_dev_msg msg = { 0 };
> > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > return -EINVAL;
> > > > >
> > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > - msg.req.iova.start = start;
> > > > > - msg.req.iova.last = last;
> > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > + msg.req.iova.start = start;
> > > > > + msg.req.iova.last = last;
> > > > > + } else {
> > > > > + msg.req.iova_v2.start = start;
> > > > > + msg.req.iova_v2.last = last;
> > > > > + msg.req.iova_v2.asid = asid;
> > > > > + }
> > > > >
> > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > }
> > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > return mask;
> > > > > }
> > > > >
> > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > + unsigned int group, unsigned int asid)
> > > > > +{
> > > > > + mutex_lock(&dev->domain_lock);
> > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > + mutex_unlock(&dev->domain_lock);
> > > > > +}
> > > > > +
> > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > {
> > > > > int i;
> > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > >
> > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > - if (domain && domain->bounce_map)
> > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > +
> > > > > + if (domain && domain->bounce_map)
> > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > + }
> > > > > +
> > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > >
> > > > > down_write(&dev->rwsem);
> > > > >
> > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > return ret;
> > > > > }
> > > > >
> > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > + unsigned int asid)
> > > > > +{
> > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > + int r;
> > > > > +
> > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > + return -EINVAL;
> > > > > +
> > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > + msg.req.vq_group_asid.group = group;
> > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > +
> > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > + if (r < 0)
> > > > > + return r;
> > > > > +
> > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > + return 0;
> > > > > +}
> > > > > +
> > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > struct vdpa_vq_state *state)
> > > > > {
> > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > int ret;
> > > > >
> > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > if (ret)
> > > > > return ret;
> > > > >
> > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > if (ret) {
> > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > return ret;
> > > > > }
> > > > >
> > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > .reset = vduse_vdpa_reset,
> > > > > .set_map = vduse_vdpa_set_map,
> > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > .get_vq_map = vduse_get_vq_map,
> > > > > .free = vduse_vdpa_free,
> > > > > };
> > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > return;
> > > > >
> > > > > vdev = token.group->dev;
> > > > > - domain = vdev->domain;
> > > > > -
> > > > > + mutex_lock(&vdev->domain_lock);
> > > > > + domain = token.group->as->domain;
> > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > }
> > > > >
> > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > return;
> > > > >
> > > > > vdev = token.group->dev;
> > > > > - domain = vdev->domain;
> > > > > -
> > > > > + mutex_lock(&vdev->domain_lock);
> > > > > + domain = token.group->as->domain;
> > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > }
> > > > >
> > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > {
> > > > > struct vduse_dev *vdev;
> > > > > struct vduse_iova_domain *domain;
> > > > > + dma_addr_t r;
> > > > >
> > > > > if (!token.group)
> > > > > return DMA_MAPPING_ERROR;
> > > > >
> > > > > vdev = token.group->dev;
> > > > > - domain = vdev->domain;
> > > > > + mutex_lock(&vdev->domain_lock);
> > > >
> > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > atomic context. And I think we can just remove it since creation and
> > > > deletion operations of the iova domain are guaranteed not to execute
> > > > concurrently with I/O operations.
> > > >
> > >
> > > That would be great indeed! Can you expand on this, what protects here
> > > from the moment the two syscalls are issues from userland?
> > >
> >
> > The domain mutex lock is introduced in commit
> > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > creation"). It's used to prevent concurrent execution between
> > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > would not be called until vdpa_dev_add() completed, so the mutex lock
> > is not needed.
> >
>
> Yes, but the usage is extended here to also protect from concurrent
> calls to vduse_dev_map_page and vduse_set_group_asid or similar.
>
> So I guess the best is to replace it with a spinlock or RCU.
>
OK, I see, we simply aim to prevent concurrent access to the group->as
variable here. But I wonder if the .set_group_asid function can be
called during I/O. I think the unmap_page() would fail if we change
the group->as between map_page() and unmap_page(). Besides, it seems
that .set_group_asid is only called in the vhost-vdpa case currently,
but the dma ops such as map_page/unmap_page only service the
virtio-vdpa case, so they would not be called concurrently with
.set_group_asid now.
Thanks,
Yongji
On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
>
> On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> <eperezma@redhat.com> wrote:
> >
> > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > >
> > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > <eperezma@redhat.com> wrote:
> > > >
> > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > >
> > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > >
> > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > >
> > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > >
> > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > ---
> > > > > > v8:
> > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > justify it.
> > > > > >
> > > > > > v7:
> > > > > > * Take write lock in the error path (Jason).
> > > > > >
> > > > > > v6:
> > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > (MST).
> > > > > > * Fix struct name not matching in the doc.
> > > > > >
> > > > > > v5:
> > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > ioctl (Jason).
> > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > vduse_dev_request.
> > > > > >
> > > > > > v4:
> > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > return; } (Jason)
> > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > >
> > > > > > v3:
> > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > (Jason).
> > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > (Jason)
> > > > > >
> > > > > > v2:
> > > > > > * Convert the use of mutex to rwlock.
> > > > > >
> > > > > > RFC v3:
> > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > ASIDs.
> > > > > >
> > > > > > RFC v2:
> > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > part of the struct is the same.
> > > > > > ---
> > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > @@ -41,6 +41,7 @@
> > > > > >
> > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > struct mm_struct *mm;
> > > > > > };
> > > > > >
> > > > > > +struct vduse_as {
> > > > > > + struct vduse_iova_domain *domain;
> > > > > > + struct vduse_umem *umem;
> > > > > > + struct mutex mem_lock;
> > > > > > +};
> > > > > > +
> > > > > > struct vduse_vq_group {
> > > > > > + struct vduse_as *as;
> > > > > > struct vduse_dev *dev;
> > > > > > };
> > > > > >
> > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > struct vduse_vdpa *vdev;
> > > > > > struct device *dev;
> > > > > > struct vduse_virtqueue **vqs;
> > > > > > - struct vduse_iova_domain *domain;
> > > > > > + struct vduse_as *as;
> > > > > > char *name;
> > > > > > struct mutex lock;
> > > > > > spinlock_t msg_lock;
> > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > u32 vq_num;
> > > > > > u32 vq_align;
> > > > > > u32 ngroups;
> > > > > > - struct vduse_umem *umem;
> > > > > > + u32 nas;
> > > > > > struct vduse_vq_group *groups;
> > > > > > - struct mutex mem_lock;
> > > > > > unsigned int bounce_size;
> > > > > > struct mutex domain_lock;
> > > > > > };
> > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > }
> > > > > >
> > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > u64 start, u64 last)
> > > > > > {
> > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > return -EINVAL;
> > > > > >
> > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > - msg.req.iova.start = start;
> > > > > > - msg.req.iova.last = last;
> > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > + msg.req.iova.start = start;
> > > > > > + msg.req.iova.last = last;
> > > > > > + } else {
> > > > > > + msg.req.iova_v2.start = start;
> > > > > > + msg.req.iova_v2.last = last;
> > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > + }
> > > > > >
> > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > }
> > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > return mask;
> > > > > > }
> > > > > >
> > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > + unsigned int group, unsigned int asid)
> > > > > > +{
> > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > +}
> > > > > > +
> > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > {
> > > > > > int i;
> > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > >
> > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > - if (domain && domain->bounce_map)
> > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > +
> > > > > > + if (domain && domain->bounce_map)
> > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > + }
> > > > > > +
> > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > >
> > > > > > down_write(&dev->rwsem);
> > > > > >
> > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > return ret;
> > > > > > }
> > > > > >
> > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > + unsigned int asid)
> > > > > > +{
> > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > + int r;
> > > > > > +
> > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > + return -EINVAL;
> > > > > > +
> > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > +
> > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > + if (r < 0)
> > > > > > + return r;
> > > > > > +
> > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > struct vdpa_vq_state *state)
> > > > > > {
> > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > int ret;
> > > > > >
> > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > if (ret)
> > > > > > return ret;
> > > > > >
> > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > if (ret) {
> > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > return ret;
> > > > > > }
> > > > > >
> > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > .reset = vduse_vdpa_reset,
> > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > .free = vduse_vdpa_free,
> > > > > > };
> > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > return;
> > > > > >
> > > > > > vdev = token.group->dev;
> > > > > > - domain = vdev->domain;
> > > > > > -
> > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > + domain = token.group->as->domain;
> > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > }
> > > > > >
> > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > return;
> > > > > >
> > > > > > vdev = token.group->dev;
> > > > > > - domain = vdev->domain;
> > > > > > -
> > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > + domain = token.group->as->domain;
> > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > }
> > > > > >
> > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > {
> > > > > > struct vduse_dev *vdev;
> > > > > > struct vduse_iova_domain *domain;
> > > > > > + dma_addr_t r;
> > > > > >
> > > > > > if (!token.group)
> > > > > > return DMA_MAPPING_ERROR;
> > > > > >
> > > > > > vdev = token.group->dev;
> > > > > > - domain = vdev->domain;
> > > > > > + mutex_lock(&vdev->domain_lock);
> > > > >
> > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > atomic context. And I think we can just remove it since creation and
> > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > concurrently with I/O operations.
> > > > >
> > > >
> > > > That would be great indeed! Can you expand on this, what protects here
> > > > from the moment the two syscalls are issues from userland?
> > > >
> > >
> > > The domain mutex lock is introduced in commit
> > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > creation"). It's used to prevent concurrent execution between
> > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > is not needed.
> > >
> >
> > Yes, but the usage is extended here to also protect from concurrent
> > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> >
> > So I guess the best is to replace it with a spinlock or RCU.
> >
>
> OK, I see, we simply aim to prevent concurrent access to the group->as
> variable here. But I wonder if the .set_group_asid function can be
> called during I/O.
At least a malicious userland app could do it.
> I think the unmap_page() would fail if we change
> the group->as between map_page() and unmap_page().
I guess a SIGSEGV or similar could be a valid outcome of that, but we
need to protect the "as" pointer anyway.
> Besides, it seems
> that .set_group_asid is only called in the vhost-vdpa case currently,
> but the dma ops such as map_page/unmap_page only service the
> virtio-vdpa case, so they would not be called concurrently with
> .set_group_asid now.
>
That's totally true but a malicious app can do it anyway. So it is
better to protect it properly.
Preparing a new version with a spinlock or RCU, thanks!
On Mon, Nov 3, 2025 at 2:41 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
>
> On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> > <eperezma@redhat.com> wrote:
> > >
> > > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > >
> > > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > > <eperezma@redhat.com> wrote:
> > > > >
> > > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > >
> > > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > > >
> > > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > > >
> > > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > > >
> > > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > > ---
> > > > > > > v8:
> > > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > > justify it.
> > > > > > >
> > > > > > > v7:
> > > > > > > * Take write lock in the error path (Jason).
> > > > > > >
> > > > > > > v6:
> > > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > > (MST).
> > > > > > > * Fix struct name not matching in the doc.
> > > > > > >
> > > > > > > v5:
> > > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > > ioctl (Jason).
> > > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > > vduse_dev_request.
> > > > > > >
> > > > > > > v4:
> > > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > > return; } (Jason)
> > > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > > >
> > > > > > > v3:
> > > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > > (Jason).
> > > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > > (Jason)
> > > > > > >
> > > > > > > v2:
> > > > > > > * Convert the use of mutex to rwlock.
> > > > > > >
> > > > > > > RFC v3:
> > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > > ASIDs.
> > > > > > >
> > > > > > > RFC v2:
> > > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > > part of the struct is the same.
> > > > > > > ---
> > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > @@ -41,6 +41,7 @@
> > > > > > >
> > > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > > struct mm_struct *mm;
> > > > > > > };
> > > > > > >
> > > > > > > +struct vduse_as {
> > > > > > > + struct vduse_iova_domain *domain;
> > > > > > > + struct vduse_umem *umem;
> > > > > > > + struct mutex mem_lock;
> > > > > > > +};
> > > > > > > +
> > > > > > > struct vduse_vq_group {
> > > > > > > + struct vduse_as *as;
> > > > > > > struct vduse_dev *dev;
> > > > > > > };
> > > > > > >
> > > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > > struct vduse_vdpa *vdev;
> > > > > > > struct device *dev;
> > > > > > > struct vduse_virtqueue **vqs;
> > > > > > > - struct vduse_iova_domain *domain;
> > > > > > > + struct vduse_as *as;
> > > > > > > char *name;
> > > > > > > struct mutex lock;
> > > > > > > spinlock_t msg_lock;
> > > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > > u32 vq_num;
> > > > > > > u32 vq_align;
> > > > > > > u32 ngroups;
> > > > > > > - struct vduse_umem *umem;
> > > > > > > + u32 nas;
> > > > > > > struct vduse_vq_group *groups;
> > > > > > > - struct mutex mem_lock;
> > > > > > > unsigned int bounce_size;
> > > > > > > struct mutex domain_lock;
> > > > > > > };
> > > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > }
> > > > > > >
> > > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > > u64 start, u64 last)
> > > > > > > {
> > > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > return -EINVAL;
> > > > > > >
> > > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > > - msg.req.iova.start = start;
> > > > > > > - msg.req.iova.last = last;
> > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > > + msg.req.iova.start = start;
> > > > > > > + msg.req.iova.last = last;
> > > > > > > + } else {
> > > > > > > + msg.req.iova_v2.start = start;
> > > > > > > + msg.req.iova_v2.last = last;
> > > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > > + }
> > > > > > >
> > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > }
> > > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > > return mask;
> > > > > > > }
> > > > > > >
> > > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > > + unsigned int group, unsigned int asid)
> > > > > > > +{
> > > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > > +}
> > > > > > > +
> > > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > > {
> > > > > > > int i;
> > > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > > >
> > > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > > - if (domain && domain->bounce_map)
> > > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > > +
> > > > > > > + if (domain && domain->bounce_map)
> > > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > > + }
> > > > > > > +
> > > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > > >
> > > > > > > down_write(&dev->rwsem);
> > > > > > >
> > > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > > return ret;
> > > > > > > }
> > > > > > >
> > > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > > + unsigned int asid)
> > > > > > > +{
> > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > + int r;
> > > > > > > +
> > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > > + return -EINVAL;
> > > > > > > +
> > > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > > +
> > > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > > + if (r < 0)
> > > > > > > + return r;
> > > > > > > +
> > > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > > + return 0;
> > > > > > > +}
> > > > > > > +
> > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > > struct vdpa_vq_state *state)
> > > > > > > {
> > > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > int ret;
> > > > > > >
> > > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > > if (ret)
> > > > > > > return ret;
> > > > > > >
> > > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > > if (ret) {
> > > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > > return ret;
> > > > > > > }
> > > > > > >
> > > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > > .reset = vduse_vdpa_reset,
> > > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > > .free = vduse_vdpa_free,
> > > > > > > };
> > > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > > return;
> > > > > > >
> > > > > > > vdev = token.group->dev;
> > > > > > > - domain = vdev->domain;
> > > > > > > -
> > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > + domain = token.group->as->domain;
> > > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > }
> > > > > > >
> > > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > return;
> > > > > > >
> > > > > > > vdev = token.group->dev;
> > > > > > > - domain = vdev->domain;
> > > > > > > -
> > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > + domain = token.group->as->domain;
> > > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > }
> > > > > > >
> > > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > {
> > > > > > > struct vduse_dev *vdev;
> > > > > > > struct vduse_iova_domain *domain;
> > > > > > > + dma_addr_t r;
> > > > > > >
> > > > > > > if (!token.group)
> > > > > > > return DMA_MAPPING_ERROR;
> > > > > > >
> > > > > > > vdev = token.group->dev;
> > > > > > > - domain = vdev->domain;
> > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > >
> > > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > > atomic context. And I think we can just remove it since creation and
> > > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > > concurrently with I/O operations.
> > > > > >
> > > > >
> > > > > That would be great indeed! Can you expand on this, what protects here
> > > > > from the moment the two syscalls are issues from userland?
> > > > >
> > > >
> > > > The domain mutex lock is introduced in commit
> > > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > > creation"). It's used to prevent concurrent execution between
> > > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > > is not needed.
> > > >
> > >
> > > Yes, but the usage is extended here to also protect from concurrent
> > > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> > >
> > > So I guess the best is to replace it with a spinlock or RCU.
> > >
> >
> > OK, I see, we simply aim to prevent concurrent access to the group->as
> > variable here. But I wonder if the .set_group_asid function can be
> > called during I/O.
>
> At least a malicious userland app could do it.
>
> > I think the unmap_page() would fail if we change
> > the group->as between map_page() and unmap_page().
>
> I guess a SIGSEGV or similar could be a valid outcome of that, but we
> need to protect the "as" pointer anyway.
>
> > Besides, it seems
> > that .set_group_asid is only called in the vhost-vdpa case currently,
> > but the dma ops such as map_page/unmap_page only service the
> > virtio-vdpa case, so they would not be called concurrently with
> > .set_group_asid now.
> >
>
> That's totally true but a malicious app can do it anyway. So it is
> better to protect it properly.
>
Actually there is no interface for userspace to call .set_group_asid
if the vduse device is binded to the virtio-vdpa driver.
> Preparing a new version with a spinlock or RCU, thanks!
>
If so, we'd better introduce a new RCU lock here rather than using the
domain lock.
Thanks,
Yongji
On Mon, Nov 3, 2025 at 8:13 AM Yongji Xie <xieyongji@bytedance.com> wrote:
>
> On Mon, Nov 3, 2025 at 2:41 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> >
> > On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > >
> > > On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> > > <eperezma@redhat.com> wrote:
> > > >
> > > > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > >
> > > > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > > > <eperezma@redhat.com> wrote:
> > > > > >
> > > > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > >
> > > > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > > > >
> > > > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > > > >
> > > > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > > > >
> > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > > > ---
> > > > > > > > v8:
> > > > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > > > justify it.
> > > > > > > >
> > > > > > > > v7:
> > > > > > > > * Take write lock in the error path (Jason).
> > > > > > > >
> > > > > > > > v6:
> > > > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > > > (MST).
> > > > > > > > * Fix struct name not matching in the doc.
> > > > > > > >
> > > > > > > > v5:
> > > > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > > > ioctl (Jason).
> > > > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > > > vduse_dev_request.
> > > > > > > >
> > > > > > > > v4:
> > > > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > > > return; } (Jason)
> > > > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > > > >
> > > > > > > > v3:
> > > > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > > > (Jason).
> > > > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > > > (Jason)
> > > > > > > >
> > > > > > > > v2:
> > > > > > > > * Convert the use of mutex to rwlock.
> > > > > > > >
> > > > > > > > RFC v3:
> > > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > > > ASIDs.
> > > > > > > >
> > > > > > > > RFC v2:
> > > > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > > > part of the struct is the same.
> > > > > > > > ---
> > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > > > >
> > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > @@ -41,6 +41,7 @@
> > > > > > > >
> > > > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > > > struct mm_struct *mm;
> > > > > > > > };
> > > > > > > >
> > > > > > > > +struct vduse_as {
> > > > > > > > + struct vduse_iova_domain *domain;
> > > > > > > > + struct vduse_umem *umem;
> > > > > > > > + struct mutex mem_lock;
> > > > > > > > +};
> > > > > > > > +
> > > > > > > > struct vduse_vq_group {
> > > > > > > > + struct vduse_as *as;
> > > > > > > > struct vduse_dev *dev;
> > > > > > > > };
> > > > > > > >
> > > > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > > > struct vduse_vdpa *vdev;
> > > > > > > > struct device *dev;
> > > > > > > > struct vduse_virtqueue **vqs;
> > > > > > > > - struct vduse_iova_domain *domain;
> > > > > > > > + struct vduse_as *as;
> > > > > > > > char *name;
> > > > > > > > struct mutex lock;
> > > > > > > > spinlock_t msg_lock;
> > > > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > > > u32 vq_num;
> > > > > > > > u32 vq_align;
> > > > > > > > u32 ngroups;
> > > > > > > > - struct vduse_umem *umem;
> > > > > > > > + u32 nas;
> > > > > > > > struct vduse_vq_group *groups;
> > > > > > > > - struct mutex mem_lock;
> > > > > > > > unsigned int bounce_size;
> > > > > > > > struct mutex domain_lock;
> > > > > > > > };
> > > > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > }
> > > > > > > >
> > > > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > > > u64 start, u64 last)
> > > > > > > > {
> > > > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > return -EINVAL;
> > > > > > > >
> > > > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > > > - msg.req.iova.start = start;
> > > > > > > > - msg.req.iova.last = last;
> > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > > > + msg.req.iova.start = start;
> > > > > > > > + msg.req.iova.last = last;
> > > > > > > > + } else {
> > > > > > > > + msg.req.iova_v2.start = start;
> > > > > > > > + msg.req.iova_v2.last = last;
> > > > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > > > + }
> > > > > > > >
> > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > }
> > > > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > > > return mask;
> > > > > > > > }
> > > > > > > >
> > > > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > > > + unsigned int group, unsigned int asid)
> > > > > > > > +{
> > > > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > > > +}
> > > > > > > > +
> > > > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > > > {
> > > > > > > > int i;
> > > > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > > > >
> > > > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > > > - if (domain && domain->bounce_map)
> > > > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > > > +
> > > > > > > > + if (domain && domain->bounce_map)
> > > > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > > > + }
> > > > > > > > +
> > > > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > > > >
> > > > > > > > down_write(&dev->rwsem);
> > > > > > > >
> > > > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > > > return ret;
> > > > > > > > }
> > > > > > > >
> > > > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > > > + unsigned int asid)
> > > > > > > > +{
> > > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > > + int r;
> > > > > > > > +
> > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > > > + return -EINVAL;
> > > > > > > > +
> > > > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > > > +
> > > > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > > > + if (r < 0)
> > > > > > > > + return r;
> > > > > > > > +
> > > > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > > > + return 0;
> > > > > > > > +}
> > > > > > > > +
> > > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > > > struct vdpa_vq_state *state)
> > > > > > > > {
> > > > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > int ret;
> > > > > > > >
> > > > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > > > if (ret)
> > > > > > > > return ret;
> > > > > > > >
> > > > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > > > if (ret) {
> > > > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > > > return ret;
> > > > > > > > }
> > > > > > > >
> > > > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > > > .reset = vduse_vdpa_reset,
> > > > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > > > .free = vduse_vdpa_free,
> > > > > > > > };
> > > > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > > > return;
> > > > > > > >
> > > > > > > > vdev = token.group->dev;
> > > > > > > > - domain = vdev->domain;
> > > > > > > > -
> > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > + domain = token.group->as->domain;
> > > > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > }
> > > > > > > >
> > > > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > return;
> > > > > > > >
> > > > > > > > vdev = token.group->dev;
> > > > > > > > - domain = vdev->domain;
> > > > > > > > -
> > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > + domain = token.group->as->domain;
> > > > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > }
> > > > > > > >
> > > > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > {
> > > > > > > > struct vduse_dev *vdev;
> > > > > > > > struct vduse_iova_domain *domain;
> > > > > > > > + dma_addr_t r;
> > > > > > > >
> > > > > > > > if (!token.group)
> > > > > > > > return DMA_MAPPING_ERROR;
> > > > > > > >
> > > > > > > > vdev = token.group->dev;
> > > > > > > > - domain = vdev->domain;
> > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > >
> > > > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > > > atomic context. And I think we can just remove it since creation and
> > > > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > > > concurrently with I/O operations.
> > > > > > >
> > > > > >
> > > > > > That would be great indeed! Can you expand on this, what protects here
> > > > > > from the moment the two syscalls are issues from userland?
> > > > > >
> > > > >
> > > > > The domain mutex lock is introduced in commit
> > > > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > > > creation"). It's used to prevent concurrent execution between
> > > > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > > > is not needed.
> > > > >
> > > >
> > > > Yes, but the usage is extended here to also protect from concurrent
> > > > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> > > >
> > > > So I guess the best is to replace it with a spinlock or RCU.
> > > >
> > >
> > > OK, I see, we simply aim to prevent concurrent access to the group->as
> > > variable here. But I wonder if the .set_group_asid function can be
> > > called during I/O.
> >
> > At least a malicious userland app could do it.
> >
> > > I think the unmap_page() would fail if we change
> > > the group->as between map_page() and unmap_page().
> >
> > I guess a SIGSEGV or similar could be a valid outcome of that, but we
> > need to protect the "as" pointer anyway.
> >
> > > Besides, it seems
> > > that .set_group_asid is only called in the vhost-vdpa case currently,
> > > but the dma ops such as map_page/unmap_page only service the
> > > virtio-vdpa case, so they would not be called concurrently with
> > > .set_group_asid now.
> > >
> >
> > That's totally true but a malicious app can do it anyway. So it is
> > better to protect it properly.
> >
>
> Actually there is no interface for userspace to call .set_group_asid
> if the vduse device is binded to the virtio-vdpa driver.
>
It is possible from vhost-vdpa.
On Mon, Nov 3, 2025 at 4:20 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
>
> On Mon, Nov 3, 2025 at 8:13 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Mon, Nov 3, 2025 at 2:41 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> > >
> > > On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > >
> > > > On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> > > > <eperezma@redhat.com> wrote:
> > > > >
> > > > > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > >
> > > > > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > > > > <eperezma@redhat.com> wrote:
> > > > > > >
> > > > > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > > >
> > > > > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > > > > >
> > > > > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > > > > >
> > > > > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > > > > >
> > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > > > > ---
> > > > > > > > > v8:
> > > > > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > > > > justify it.
> > > > > > > > >
> > > > > > > > > v7:
> > > > > > > > > * Take write lock in the error path (Jason).
> > > > > > > > >
> > > > > > > > > v6:
> > > > > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > > > > (MST).
> > > > > > > > > * Fix struct name not matching in the doc.
> > > > > > > > >
> > > > > > > > > v5:
> > > > > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > > > > ioctl (Jason).
> > > > > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > > > > vduse_dev_request.
> > > > > > > > >
> > > > > > > > > v4:
> > > > > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > > > > return; } (Jason)
> > > > > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > > > > >
> > > > > > > > > v3:
> > > > > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > > > > (Jason).
> > > > > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > > > > (Jason)
> > > > > > > > >
> > > > > > > > > v2:
> > > > > > > > > * Convert the use of mutex to rwlock.
> > > > > > > > >
> > > > > > > > > RFC v3:
> > > > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > > > > ASIDs.
> > > > > > > > >
> > > > > > > > > RFC v2:
> > > > > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > > > > part of the struct is the same.
> > > > > > > > > ---
> > > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > @@ -41,6 +41,7 @@
> > > > > > > > >
> > > > > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > > > > struct mm_struct *mm;
> > > > > > > > > };
> > > > > > > > >
> > > > > > > > > +struct vduse_as {
> > > > > > > > > + struct vduse_iova_domain *domain;
> > > > > > > > > + struct vduse_umem *umem;
> > > > > > > > > + struct mutex mem_lock;
> > > > > > > > > +};
> > > > > > > > > +
> > > > > > > > > struct vduse_vq_group {
> > > > > > > > > + struct vduse_as *as;
> > > > > > > > > struct vduse_dev *dev;
> > > > > > > > > };
> > > > > > > > >
> > > > > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > > > > struct vduse_vdpa *vdev;
> > > > > > > > > struct device *dev;
> > > > > > > > > struct vduse_virtqueue **vqs;
> > > > > > > > > - struct vduse_iova_domain *domain;
> > > > > > > > > + struct vduse_as *as;
> > > > > > > > > char *name;
> > > > > > > > > struct mutex lock;
> > > > > > > > > spinlock_t msg_lock;
> > > > > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > > > > u32 vq_num;
> > > > > > > > > u32 vq_align;
> > > > > > > > > u32 ngroups;
> > > > > > > > > - struct vduse_umem *umem;
> > > > > > > > > + u32 nas;
> > > > > > > > > struct vduse_vq_group *groups;
> > > > > > > > > - struct mutex mem_lock;
> > > > > > > > > unsigned int bounce_size;
> > > > > > > > > struct mutex domain_lock;
> > > > > > > > > };
> > > > > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > > > > u64 start, u64 last)
> > > > > > > > > {
> > > > > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > return -EINVAL;
> > > > > > > > >
> > > > > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > > > > - msg.req.iova.start = start;
> > > > > > > > > - msg.req.iova.last = last;
> > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > > > > + msg.req.iova.start = start;
> > > > > > > > > + msg.req.iova.last = last;
> > > > > > > > > + } else {
> > > > > > > > > + msg.req.iova_v2.start = start;
> > > > > > > > > + msg.req.iova_v2.last = last;
> > > > > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > > > > + }
> > > > > > > > >
> > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > }
> > > > > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > > > > return mask;
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > > > > + unsigned int group, unsigned int asid)
> > > > > > > > > +{
> > > > > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > > > > {
> > > > > > > > > int i;
> > > > > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > > > > >
> > > > > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > > > > - if (domain && domain->bounce_map)
> > > > > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > > > > +
> > > > > > > > > + if (domain && domain->bounce_map)
> > > > > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > > > > + }
> > > > > > > > > +
> > > > > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > > > > >
> > > > > > > > > down_write(&dev->rwsem);
> > > > > > > > >
> > > > > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > > > > return ret;
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > > > > + unsigned int asid)
> > > > > > > > > +{
> > > > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > > > + int r;
> > > > > > > > > +
> > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > > > > + return -EINVAL;
> > > > > > > > > +
> > > > > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > > > > +
> > > > > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > + if (r < 0)
> > > > > > > > > + return r;
> > > > > > > > > +
> > > > > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > > > > + return 0;
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > > > > struct vdpa_vq_state *state)
> > > > > > > > > {
> > > > > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > int ret;
> > > > > > > > >
> > > > > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > > > > if (ret)
> > > > > > > > > return ret;
> > > > > > > > >
> > > > > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > > > > if (ret) {
> > > > > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > > > > return ret;
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > > > > .reset = vduse_vdpa_reset,
> > > > > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > > > > .free = vduse_vdpa_free,
> > > > > > > > > };
> > > > > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > > > > return;
> > > > > > > > >
> > > > > > > > > vdev = token.group->dev;
> > > > > > > > > - domain = vdev->domain;
> > > > > > > > > -
> > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > return;
> > > > > > > > >
> > > > > > > > > vdev = token.group->dev;
> > > > > > > > > - domain = vdev->domain;
> > > > > > > > > -
> > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > {
> > > > > > > > > struct vduse_dev *vdev;
> > > > > > > > > struct vduse_iova_domain *domain;
> > > > > > > > > + dma_addr_t r;
> > > > > > > > >
> > > > > > > > > if (!token.group)
> > > > > > > > > return DMA_MAPPING_ERROR;
> > > > > > > > >
> > > > > > > > > vdev = token.group->dev;
> > > > > > > > > - domain = vdev->domain;
> > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > >
> > > > > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > > > > atomic context. And I think we can just remove it since creation and
> > > > > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > > > > concurrently with I/O operations.
> > > > > > > >
> > > > > > >
> > > > > > > That would be great indeed! Can you expand on this, what protects here
> > > > > > > from the moment the two syscalls are issues from userland?
> > > > > > >
> > > > > >
> > > > > > The domain mutex lock is introduced in commit
> > > > > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > > > > creation"). It's used to prevent concurrent execution between
> > > > > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > > > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > > > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > > > > is not needed.
> > > > > >
> > > > >
> > > > > Yes, but the usage is extended here to also protect from concurrent
> > > > > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> > > > >
> > > > > So I guess the best is to replace it with a spinlock or RCU.
> > > > >
> > > >
> > > > OK, I see, we simply aim to prevent concurrent access to the group->as
> > > > variable here. But I wonder if the .set_group_asid function can be
> > > > called during I/O.
> > >
> > > At least a malicious userland app could do it.
> > >
> > > > I think the unmap_page() would fail if we change
> > > > the group->as between map_page() and unmap_page().
> > >
> > > I guess a SIGSEGV or similar could be a valid outcome of that, but we
> > > need to protect the "as" pointer anyway.
> > >
> > > > Besides, it seems
> > > > that .set_group_asid is only called in the vhost-vdpa case currently,
> > > > but the dma ops such as map_page/unmap_page only service the
> > > > virtio-vdpa case, so they would not be called concurrently with
> > > > .set_group_asid now.
> > > >
> > >
> > > That's totally true but a malicious app can do it anyway. So it is
> > > better to protect it properly.
> > >
> >
> > Actually there is no interface for userspace to call .set_group_asid
> > if the vduse device is binded to the virtio-vdpa driver.
> >
>
> It is possible from vhost-vdpa.
>
Then there is no interface for userspace to call dma_ops such as
map_page/unmap_page if the device is binded to the vhost-vdpa driver.
Thanks,
Yongji
On Mon, Nov 3, 2025 at 4:56 PM Yongji Xie <xieyongji@bytedance.com> wrote:
>
> On Mon, Nov 3, 2025 at 4:20 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> >
> > On Mon, Nov 3, 2025 at 8:13 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > >
> > > On Mon, Nov 3, 2025 at 2:41 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> > > >
> > > > On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > >
> > > > > On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> > > > > <eperezma@redhat.com> wrote:
> > > > > >
> > > > > > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > >
> > > > > > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > > > > > <eperezma@redhat.com> wrote:
> > > > > > > >
> > > > > > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > > > > > >
> > > > > > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > > > > > >
> > > > > > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > > > > > >
> > > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > > > > > ---
> > > > > > > > > > v8:
> > > > > > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > > > > > justify it.
> > > > > > > > > >
> > > > > > > > > > v7:
> > > > > > > > > > * Take write lock in the error path (Jason).
> > > > > > > > > >
> > > > > > > > > > v6:
> > > > > > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > > > > > (MST).
> > > > > > > > > > * Fix struct name not matching in the doc.
> > > > > > > > > >
> > > > > > > > > > v5:
> > > > > > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > > > > > ioctl (Jason).
> > > > > > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > > > > > vduse_dev_request.
> > > > > > > > > >
> > > > > > > > > > v4:
> > > > > > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > > > > > return; } (Jason)
> > > > > > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > > > > > >
> > > > > > > > > > v3:
> > > > > > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > > > > > (Jason).
> > > > > > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > > > > > (Jason)
> > > > > > > > > >
> > > > > > > > > > v2:
> > > > > > > > > > * Convert the use of mutex to rwlock.
> > > > > > > > > >
> > > > > > > > > > RFC v3:
> > > > > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > > > > > ASIDs.
> > > > > > > > > >
> > > > > > > > > > RFC v2:
> > > > > > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > > > > > part of the struct is the same.
> > > > > > > > > > ---
> > > > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > > > > > >
> > > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > @@ -41,6 +41,7 @@
> > > > > > > > > >
> > > > > > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > > > > > struct mm_struct *mm;
> > > > > > > > > > };
> > > > > > > > > >
> > > > > > > > > > +struct vduse_as {
> > > > > > > > > > + struct vduse_iova_domain *domain;
> > > > > > > > > > + struct vduse_umem *umem;
> > > > > > > > > > + struct mutex mem_lock;
> > > > > > > > > > +};
> > > > > > > > > > +
> > > > > > > > > > struct vduse_vq_group {
> > > > > > > > > > + struct vduse_as *as;
> > > > > > > > > > struct vduse_dev *dev;
> > > > > > > > > > };
> > > > > > > > > >
> > > > > > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > > > > > struct vduse_vdpa *vdev;
> > > > > > > > > > struct device *dev;
> > > > > > > > > > struct vduse_virtqueue **vqs;
> > > > > > > > > > - struct vduse_iova_domain *domain;
> > > > > > > > > > + struct vduse_as *as;
> > > > > > > > > > char *name;
> > > > > > > > > > struct mutex lock;
> > > > > > > > > > spinlock_t msg_lock;
> > > > > > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > > > > > u32 vq_num;
> > > > > > > > > > u32 vq_align;
> > > > > > > > > > u32 ngroups;
> > > > > > > > > > - struct vduse_umem *umem;
> > > > > > > > > > + u32 nas;
> > > > > > > > > > struct vduse_vq_group *groups;
> > > > > > > > > > - struct mutex mem_lock;
> > > > > > > > > > unsigned int bounce_size;
> > > > > > > > > > struct mutex domain_lock;
> > > > > > > > > > };
> > > > > > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > > > > > u64 start, u64 last)
> > > > > > > > > > {
> > > > > > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > > return -EINVAL;
> > > > > > > > > >
> > > > > > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > > > > > - msg.req.iova.start = start;
> > > > > > > > > > - msg.req.iova.last = last;
> > > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > > > > > + msg.req.iova.start = start;
> > > > > > > > > > + msg.req.iova.last = last;
> > > > > > > > > > + } else {
> > > > > > > > > > + msg.req.iova_v2.start = start;
> > > > > > > > > > + msg.req.iova_v2.last = last;
> > > > > > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > > > > > + }
> > > > > > > > > >
> > > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > }
> > > > > > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > > > > > return mask;
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > > > > > + unsigned int group, unsigned int asid)
> > > > > > > > > > +{
> > > > > > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > > > > > {
> > > > > > > > > > int i;
> > > > > > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > > > > > >
> > > > > > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > > > > > - if (domain && domain->bounce_map)
> > > > > > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > > > > > +
> > > > > > > > > > + if (domain && domain->bounce_map)
> > > > > > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > > > > > + }
> > > > > > > > > > +
> > > > > > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > > > > > >
> > > > > > > > > > down_write(&dev->rwsem);
> > > > > > > > > >
> > > > > > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > > > > > return ret;
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > > > > > + unsigned int asid)
> > > > > > > > > > +{
> > > > > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > > > > + int r;
> > > > > > > > > > +
> > > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > > > > > + return -EINVAL;
> > > > > > > > > > +
> > > > > > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > > > > > +
> > > > > > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > + if (r < 0)
> > > > > > > > > > + return r;
> > > > > > > > > > +
> > > > > > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > > > > > + return 0;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > > > > > struct vdpa_vq_state *state)
> > > > > > > > > > {
> > > > > > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > > int ret;
> > > > > > > > > >
> > > > > > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > > > > > if (ret)
> > > > > > > > > > return ret;
> > > > > > > > > >
> > > > > > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > > > > > if (ret) {
> > > > > > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > > > > > return ret;
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > > > > > .reset = vduse_vdpa_reset,
> > > > > > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > > > > > .free = vduse_vdpa_free,
> > > > > > > > > > };
> > > > > > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > > > > > return;
> > > > > > > > > >
> > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > -
> > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > > return;
> > > > > > > > > >
> > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > -
> > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > > {
> > > > > > > > > > struct vduse_dev *vdev;
> > > > > > > > > > struct vduse_iova_domain *domain;
> > > > > > > > > > + dma_addr_t r;
> > > > > > > > > >
> > > > > > > > > > if (!token.group)
> > > > > > > > > > return DMA_MAPPING_ERROR;
> > > > > > > > > >
> > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > >
> > > > > > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > > > > > atomic context. And I think we can just remove it since creation and
> > > > > > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > > > > > concurrently with I/O operations.
> > > > > > > > >
> > > > > > > >
> > > > > > > > That would be great indeed! Can you expand on this, what protects here
> > > > > > > > from the moment the two syscalls are issues from userland?
> > > > > > > >
> > > > > > >
> > > > > > > The domain mutex lock is introduced in commit
> > > > > > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > > > > > creation"). It's used to prevent concurrent execution between
> > > > > > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > > > > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > > > > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > > > > > is not needed.
> > > > > > >
> > > > > >
> > > > > > Yes, but the usage is extended here to also protect from concurrent
> > > > > > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> > > > > >
> > > > > > So I guess the best is to replace it with a spinlock or RCU.
> > > > > >
> > > > >
> > > > > OK, I see, we simply aim to prevent concurrent access to the group->as
> > > > > variable here. But I wonder if the .set_group_asid function can be
> > > > > called during I/O.
> > > >
> > > > At least a malicious userland app could do it.
> > > >
> > > > > I think the unmap_page() would fail if we change
> > > > > the group->as between map_page() and unmap_page().
It's better for the VUDSE to prepare for this.
> > > >
> > > > I guess a SIGSEGV or similar could be a valid outcome of that, but we
> > > > need to protect the "as" pointer anyway.
SIGSEGV is probably not suitable for the case of map/unmap as they
might be executed in bh.
> > > >
> > > > > Besides, it seems
> > > > > that .set_group_asid is only called in the vhost-vdpa case currently,
> > > > > but the dma ops such as map_page/unmap_page only service the
> > > > > virtio-vdpa case, so they would not be called concurrently with
> > > > > .set_group_asid now.
> > > > >
> > > >
> > > > That's totally true but a malicious app can do it anyway. So it is
> > > > better to protect it properly.
> > > >
> > >
> > > Actually there is no interface for userspace to call .set_group_asid
> > > if the vduse device is binded to the virtio-vdpa driver.
> > >
> >
> > It is possible from vhost-vdpa.
> >
>
> Then there is no interface for userspace to call dma_ops such as
> map_page/unmap_page if the device is binded to the vhost-vdpa driver.
>
> Thanks,
> Yongji
>
Right now, but we can't say that for the future drivers. Unless we
have a guard in the vdpa core, we probably need to prepare for that.
Thanks
On Mon, Nov 3, 2025 at 5:26 PM Jason Wang <jasowang@redhat.com> wrote:
>
> On Mon, Nov 3, 2025 at 4:56 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Mon, Nov 3, 2025 at 4:20 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> > >
> > > On Mon, Nov 3, 2025 at 8:13 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > >
> > > > On Mon, Nov 3, 2025 at 2:41 PM Eugenio Perez Martin <eperezma@redhat.com> wrote:
> > > > >
> > > > > On Mon, Nov 3, 2025 at 3:55 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > >
> > > > > > On Fri, Oct 31, 2025 at 10:09 PM Eugenio Perez Martin
> > > > > > <eperezma@redhat.com> wrote:
> > > > > > >
> > > > > > > On Fri, Oct 31, 2025 at 8:01 AM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > > >
> > > > > > > > On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
> > > > > > > > <eperezma@redhat.com> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> > > > > > > > > >
> > > > > > > > > > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > > > > > > > > > group. This enables mapping each group into a distinct memory space.
> > > > > > > > > > >
> > > > > > > > > > > Now that the driver can change ASID in the middle of operation, the
> > > > > > > > > > > domain that each vq address point is also protected by domain_lock.
> > > > > > > > > > >
> > > > > > > > > > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > > > > > > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > > > > > > > > > ---
> > > > > > > > > > > v8:
> > > > > > > > > > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > > > > > > > > > justify it.
> > > > > > > > > > >
> > > > > > > > > > > v7:
> > > > > > > > > > > * Take write lock in the error path (Jason).
> > > > > > > > > > >
> > > > > > > > > > > v6:
> > > > > > > > > > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > > > > > > > > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > > > > > > > > > (MST).
> > > > > > > > > > > * Fix struct name not matching in the doc.
> > > > > > > > > > >
> > > > > > > > > > > v5:
> > > > > > > > > > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > > > > > > > > > ioctl (Jason).
> > > > > > > > > > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > > > > > > > > > * Exclude "padding" member from the only >V1 members in
> > > > > > > > > > > vduse_dev_request.
> > > > > > > > > > >
> > > > > > > > > > > v4:
> > > > > > > > > > > * Divide each domain bounce size between the device bounce size (Jason).
> > > > > > > > > > > * revert unneeded addr = NULL assignment (Jason)
> > > > > > > > > > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > > > > > > > > > return; } (Jason)
> > > > > > > > > > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > > > > > > > > > * Consider config->nas == 0 as a fail (Jason).
> > > > > > > > > > >
> > > > > > > > > > > v3:
> > > > > > > > > > > * Get the vduse domain through the vduse_as in the map functions
> > > > > > > > > > > (Jason).
> > > > > > > > > > > * Squash with the patch creating the vduse_as struct (Jason).
> > > > > > > > > > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > > > > > > > > > (Jason)
> > > > > > > > > > >
> > > > > > > > > > > v2:
> > > > > > > > > > > * Convert the use of mutex to rwlock.
> > > > > > > > > > >
> > > > > > > > > > > RFC v3:
> > > > > > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > > > > > > > > > value to reduce memory consumption, but vqs are already limited to
> > > > > > > > > > > that value and userspace VDUSE is able to allocate that many vqs.
> > > > > > > > > > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > > > > > > > > > VDUSE_IOTLB_GET_INFO.
> > > > > > > > > > > * Use of array_index_nospec in VDUSE device ioctls.
> > > > > > > > > > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > > > > > > > > > * Move the umem mutex to asid struct so there is no contention between
> > > > > > > > > > > ASIDs.
> > > > > > > > > > >
> > > > > > > > > > > RFC v2:
> > > > > > > > > > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > > > > > > > > > part of the struct is the same.
> > > > > > > > > > > ---
> > > > > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > > > > > > > > > include/uapi/linux/vduse.h | 53 ++++-
> > > > > > > > > > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > > > > > > > > > >
> > > > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > > index 97be04f73fbf..c6909d73d06d 100644
> > > > > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > > > > @@ -41,6 +41,7 @@
> > > > > > > > > > >
> > > > > > > > > > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > > > > > > > > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > > > > > > > > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > > > > > > > > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > > > > > > > > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > > > > > > > > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > > > > > > > > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > > > > > > > > > struct mm_struct *mm;
> > > > > > > > > > > };
> > > > > > > > > > >
> > > > > > > > > > > +struct vduse_as {
> > > > > > > > > > > + struct vduse_iova_domain *domain;
> > > > > > > > > > > + struct vduse_umem *umem;
> > > > > > > > > > > + struct mutex mem_lock;
> > > > > > > > > > > +};
> > > > > > > > > > > +
> > > > > > > > > > > struct vduse_vq_group {
> > > > > > > > > > > + struct vduse_as *as;
> > > > > > > > > > > struct vduse_dev *dev;
> > > > > > > > > > > };
> > > > > > > > > > >
> > > > > > > > > > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > > > > > > > > > struct vduse_vdpa *vdev;
> > > > > > > > > > > struct device *dev;
> > > > > > > > > > > struct vduse_virtqueue **vqs;
> > > > > > > > > > > - struct vduse_iova_domain *domain;
> > > > > > > > > > > + struct vduse_as *as;
> > > > > > > > > > > char *name;
> > > > > > > > > > > struct mutex lock;
> > > > > > > > > > > spinlock_t msg_lock;
> > > > > > > > > > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > > > > > > > > > u32 vq_num;
> > > > > > > > > > > u32 vq_align;
> > > > > > > > > > > u32 ngroups;
> > > > > > > > > > > - struct vduse_umem *umem;
> > > > > > > > > > > + u32 nas;
> > > > > > > > > > > struct vduse_vq_group *groups;
> > > > > > > > > > > - struct mutex mem_lock;
> > > > > > > > > > > unsigned int bounce_size;
> > > > > > > > > > > struct mutex domain_lock;
> > > > > > > > > > > };
> > > > > > > > > > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > > > > > > > > > u64 start, u64 last)
> > > > > > > > > > > {
> > > > > > > > > > > struct vduse_dev_msg msg = { 0 };
> > > > > > > > > > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > > > > > > > > > return -EINVAL;
> > > > > > > > > > >
> > > > > > > > > > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > > > > > > > > > - msg.req.iova.start = start;
> > > > > > > > > > > - msg.req.iova.last = last;
> > > > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > > > > > > > > > + msg.req.iova.start = start;
> > > > > > > > > > > + msg.req.iova.last = last;
> > > > > > > > > > > + } else {
> > > > > > > > > > > + msg.req.iova_v2.start = start;
> > > > > > > > > > > + msg.req.iova_v2.last = last;
> > > > > > > > > > > + msg.req.iova_v2.asid = asid;
> > > > > > > > > > > + }
> > > > > > > > > > >
> > > > > > > > > > > return vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > > }
> > > > > > > > > > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > > > > > > > > > return mask;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > > > > > > > > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > > > > > > > > > + unsigned int group, unsigned int asid)
> > > > > > > > > > > +{
> > > > > > > > > > > + mutex_lock(&dev->domain_lock);
> > > > > > > > > > > + dev->groups[group].as = &dev->as[asid];
> > > > > > > > > > > + mutex_unlock(&dev->domain_lock);
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > > > > > > > > > {
> > > > > > > > > > > int i;
> > > > > > > > > > > - struct vduse_iova_domain *domain = dev->domain;
> > > > > > > > > > >
> > > > > > > > > > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > > > > > > > > > - if (domain && domain->bounce_map)
> > > > > > > > > > > - vduse_domain_reset_bounce_map(domain);
> > > > > > > > > > > + for (i = 0; i < dev->nas; i++) {
> > > > > > > > > > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > > > > > > > > > +
> > > > > > > > > > > + if (domain && domain->bounce_map)
> > > > > > > > > > > + vduse_domain_reset_bounce_map(domain);
> > > > > > > > > > > + }
> > > > > > > > > > > +
> > > > > > > > > > > + for (i = 0; i < dev->ngroups; i++)
> > > > > > > > > > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > > > > > > > > > >
> > > > > > > > > > > down_write(&dev->rwsem);
> > > > > > > > > > >
> > > > > > > > > > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > > > > > > > > > return ret;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > > > > > > > > > + unsigned int asid)
> > > > > > > > > > > +{
> > > > > > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > > > > > + int r;
> > > > > > > > > > > +
> > > > > > > > > > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > > > > > > > > > + group >= dev->ngroups || asid >= dev->nas)
> > > > > > > > > > > + return -EINVAL;
> > > > > > > > > > > +
> > > > > > > > > > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > > > > > > > > > + msg.req.vq_group_asid.group = group;
> > > > > > > > > > > + msg.req.vq_group_asid.asid = asid;
> > > > > > > > > > > +
> > > > > > > > > > > + r = vduse_dev_msg_sync(dev, &msg);
> > > > > > > > > > > + if (r < 0)
> > > > > > > > > > > + return r;
> > > > > > > > > > > +
> > > > > > > > > > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > > > > > > > > > + return 0;
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > > > > > > > > > struct vdpa_vq_state *state)
> > > > > > > > > > > {
> > > > > > > > > > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > > > > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > > > > int ret;
> > > > > > > > > > >
> > > > > > > > > > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > > > > > > > > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > > > > > > > > > if (ret)
> > > > > > > > > > > return ret;
> > > > > > > > > > >
> > > > > > > > > > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > > > > > > > > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > > > > > > > > > if (ret) {
> > > > > > > > > > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > > > > > > > > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > > > > > > > > > return ret;
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > > > > > > > > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > > > > > > > > > .reset = vduse_vdpa_reset,
> > > > > > > > > > > .set_map = vduse_vdpa_set_map,
> > > > > > > > > > > + .set_group_asid = vduse_set_group_asid,
> > > > > > > > > > > .get_vq_map = vduse_get_vq_map,
> > > > > > > > > > > .free = vduse_vdpa_free,
> > > > > > > > > > > };
> > > > > > > > > > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > > > > > > > > > return;
> > > > > > > > > > >
> > > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > > -
> > > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > > > > > > > > > return;
> > > > > > > > > > >
> > > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > > -
> > > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > > > + domain = token.group->as->domain;
> > > > > > > > > > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > > > > > > > > > + mutex_unlock(&vdev->domain_lock);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > > > > > > > > > {
> > > > > > > > > > > struct vduse_dev *vdev;
> > > > > > > > > > > struct vduse_iova_domain *domain;
> > > > > > > > > > > + dma_addr_t r;
> > > > > > > > > > >
> > > > > > > > > > > if (!token.group)
> > > > > > > > > > > return DMA_MAPPING_ERROR;
> > > > > > > > > > >
> > > > > > > > > > > vdev = token.group->dev;
> > > > > > > > > > > - domain = vdev->domain;
> > > > > > > > > > > + mutex_lock(&vdev->domain_lock);
> > > > > > > > > >
> > > > > > > > > > The mutex_lock can't be used here since the dma ops might be called in
> > > > > > > > > > atomic context. And I think we can just remove it since creation and
> > > > > > > > > > deletion operations of the iova domain are guaranteed not to execute
> > > > > > > > > > concurrently with I/O operations.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > That would be great indeed! Can you expand on this, what protects here
> > > > > > > > > from the moment the two syscalls are issues from userland?
> > > > > > > > >
> > > > > > > >
> > > > > > > > The domain mutex lock is introduced in commit
> > > > > > > > d4438d23eeeef8bb1b3a8abe418abffd60bb544a ("vduse: Delay iova domain
> > > > > > > > creation"). It's used to prevent concurrent execution between
> > > > > > > > vdpa_dev_add() and some vduse device ioctl which needs to access the
> > > > > > > > iova domain such as VDUSE_IOTLB_REG_UMEM/DEREG_UMEM. But the dma ops
> > > > > > > > would not be called until vdpa_dev_add() completed, so the mutex lock
> > > > > > > > is not needed.
> > > > > > > >
> > > > > > >
> > > > > > > Yes, but the usage is extended here to also protect from concurrent
> > > > > > > calls to vduse_dev_map_page and vduse_set_group_asid or similar.
> > > > > > >
> > > > > > > So I guess the best is to replace it with a spinlock or RCU.
> > > > > > >
> > > > > >
> > > > > > OK, I see, we simply aim to prevent concurrent access to the group->as
> > > > > > variable here. But I wonder if the .set_group_asid function can be
> > > > > > called during I/O.
> > > > >
> > > > > At least a malicious userland app could do it.
> > > > >
> > > > > > I think the unmap_page() would fail if we change
> > > > > > the group->as between map_page() and unmap_page().
>
> It's better for the VUDSE to prepare for this.
>
> > > > >
> > > > > I guess a SIGSEGV or similar could be a valid outcome of that, but we
> > > > > need to protect the "as" pointer anyway.
>
> SIGSEGV is probably not suitable for the case of map/unmap as they
> might be executed in bh.
>
> > > > >
> > > > > > Besides, it seems
> > > > > > that .set_group_asid is only called in the vhost-vdpa case currently,
> > > > > > but the dma ops such as map_page/unmap_page only service the
> > > > > > virtio-vdpa case, so they would not be called concurrently with
> > > > > > .set_group_asid now.
> > > > > >
> > > > >
> > > > > That's totally true but a malicious app can do it anyway. So it is
> > > > > better to protect it properly.
> > > > >
> > > >
> > > > Actually there is no interface for userspace to call .set_group_asid
> > > > if the vduse device is binded to the virtio-vdpa driver.
> > > >
> > >
> > > It is possible from vhost-vdpa.
> > >
> >
> > Then there is no interface for userspace to call dma_ops such as
> > map_page/unmap_page if the device is binded to the vhost-vdpa driver.
> >
> > Thanks,
> > Yongji
> >
>
> Right now, but we can't say that for the future drivers. Unless we
> have a guard in the vdpa core, we probably need to prepare for that.
>
OK, then I think we can introduce a new RCU lock here which is hurtless.
Thanks,
Yongji
On Fri, Oct 31, 2025 at 2:31 PM Eugenio Perez Martin
<eperezma@redhat.com> wrote:
>
> On Thu, Oct 30, 2025 at 12:52 PM Yongji Xie <xieyongji@bytedance.com> wrote:
> >
> > On Thu, Oct 30, 2025 at 6:01 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> > >
> > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > group. This enables mapping each group into a distinct memory space.
> > >
> > > Now that the driver can change ASID in the middle of operation, the
> > > domain that each vq address point is also protected by domain_lock.
> > >
> > > Acked-by: Jason Wang <jasowang@redhat.com>
> > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > > ---
> > > v8:
> > > * Revert the mutex to rwlock change, it needs proper profiling to
> > > justify it.
> > >
> > > v7:
> > > * Take write lock in the error path (Jason).
> > >
> > > v6:
> > > * Make vdpa_dev_add use gotos for error handling (MST).
> > > * s/(dev->api_version < 1) ?/(dev->api_version < VDUSE_API_VERSION_1) ?/
> > > (MST).
> > > * Fix struct name not matching in the doc.
> > >
> > > v5:
> > > * Properly return errno if copy_to_user returns >0 in VDUSE_IOTLB_GET_FD
> > > ioctl (Jason).
> > > * Properly set domain bounce size to divide equally between nas (Jason).
> > > * Exclude "padding" member from the only >V1 members in
> > > vduse_dev_request.
> > >
> > > v4:
> > > * Divide each domain bounce size between the device bounce size (Jason).
> > > * revert unneeded addr = NULL assignment (Jason)
> > > * Change if (x && (y || z)) return to if (x) { if (y) return; if (z)
> > > return; } (Jason)
> > > * Change a bad multiline comment, using @ caracter instead of * (Jason).
> > > * Consider config->nas == 0 as a fail (Jason).
> > >
> > > v3:
> > > * Get the vduse domain through the vduse_as in the map functions
> > > (Jason).
> > > * Squash with the patch creating the vduse_as struct (Jason).
> > > * Create VDUSE_DEV_MAX_AS instead of comparing agains a magic number
> > > (Jason)
> > >
> > > v2:
> > > * Convert the use of mutex to rwlock.
> > >
> > > RFC v3:
> > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to a lower
> > > value to reduce memory consumption, but vqs are already limited to
> > > that value and userspace VDUSE is able to allocate that many vqs.
> > > * Remove TODO about merging VDUSE_IOTLB_GET_FD ioctl with
> > > VDUSE_IOTLB_GET_INFO.
> > > * Use of array_index_nospec in VDUSE device ioctls.
> > > * Embed vduse_iotlb_entry into vduse_iotlb_entry_v2.
> > > * Move the umem mutex to asid struct so there is no contention between
> > > ASIDs.
> > >
> > > RFC v2:
> > > * Make iotlb entry the last one of vduse_iotlb_entry_v2 so the first
> > > part of the struct is the same.
> > > ---
> > > drivers/vdpa/vdpa_user/vduse_dev.c | 348 ++++++++++++++++++++---------
> > > include/uapi/linux/vduse.h | 53 ++++-
> > > 2 files changed, 292 insertions(+), 109 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > index 97be04f73fbf..c6909d73d06d 100644
> > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > @@ -41,6 +41,7 @@
> > >
> > > #define VDUSE_DEV_MAX (1U << MINORBITS)
> > > #define VDUSE_DEV_MAX_GROUPS 0xffff
> > > +#define VDUSE_DEV_MAX_AS 0xffff
> > > #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
> > > #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
> > > #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
> > > @@ -86,7 +87,14 @@ struct vduse_umem {
> > > struct mm_struct *mm;
> > > };
> > >
> > > +struct vduse_as {
> > > + struct vduse_iova_domain *domain;
> > > + struct vduse_umem *umem;
> > > + struct mutex mem_lock;
> > > +};
> > > +
> > > struct vduse_vq_group {
> > > + struct vduse_as *as;
> > > struct vduse_dev *dev;
> > > };
> > >
> > > @@ -94,7 +102,7 @@ struct vduse_dev {
> > > struct vduse_vdpa *vdev;
> > > struct device *dev;
> > > struct vduse_virtqueue **vqs;
> > > - struct vduse_iova_domain *domain;
> > > + struct vduse_as *as;
> > > char *name;
> > > struct mutex lock;
> > > spinlock_t msg_lock;
> > > @@ -122,9 +130,8 @@ struct vduse_dev {
> > > u32 vq_num;
> > > u32 vq_align;
> > > u32 ngroups;
> > > - struct vduse_umem *umem;
> > > + u32 nas;
> > > struct vduse_vq_group *groups;
> > > - struct mutex mem_lock;
> > > unsigned int bounce_size;
> > > struct mutex domain_lock;
> > > };
> > > @@ -314,7 +321,7 @@ static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > > return vduse_dev_msg_sync(dev, &msg);
> > > }
> > >
> > > -static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > +static int vduse_dev_update_iotlb(struct vduse_dev *dev, u32 asid,
> > > u64 start, u64 last)
> > > {
> > > struct vduse_dev_msg msg = { 0 };
> > > @@ -323,8 +330,14 @@ static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > > return -EINVAL;
> > >
> > > msg.req.type = VDUSE_UPDATE_IOTLB;
> > > - msg.req.iova.start = start;
> > > - msg.req.iova.last = last;
> > > + if (dev->api_version < VDUSE_API_VERSION_1) {
> > > + msg.req.iova.start = start;
> > > + msg.req.iova.last = last;
> > > + } else {
> > > + msg.req.iova_v2.start = start;
> > > + msg.req.iova_v2.last = last;
> > > + msg.req.iova_v2.asid = asid;
> > > + }
> > >
> > > return vduse_dev_msg_sync(dev, &msg);
> > > }
> > > @@ -436,14 +449,29 @@ static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
> > > return mask;
> > > }
> > >
> > > +/* Force set the asid to a vq group without a message to the VDUSE device */
> > > +static void vduse_set_group_asid_nomsg(struct vduse_dev *dev,
> > > + unsigned int group, unsigned int asid)
> > > +{
> > > + mutex_lock(&dev->domain_lock);
> > > + dev->groups[group].as = &dev->as[asid];
> > > + mutex_unlock(&dev->domain_lock);
> > > +}
> > > +
> > > static void vduse_dev_reset(struct vduse_dev *dev)
> > > {
> > > int i;
> > > - struct vduse_iova_domain *domain = dev->domain;
> > >
> > > /* The coherent mappings are handled in vduse_dev_free_coherent() */
> > > - if (domain && domain->bounce_map)
> > > - vduse_domain_reset_bounce_map(domain);
> > > + for (i = 0; i < dev->nas; i++) {
> > > + struct vduse_iova_domain *domain = dev->as[i].domain;
> > > +
> > > + if (domain && domain->bounce_map)
> > > + vduse_domain_reset_bounce_map(domain);
> > > + }
> > > +
> > > + for (i = 0; i < dev->ngroups; i++)
> > > + vduse_set_group_asid_nomsg(dev, i, 0);
> > >
> > > down_write(&dev->rwsem);
> > >
> > > @@ -623,6 +651,29 @@ static union virtio_map vduse_get_vq_map(struct vdpa_device *vdpa, u16 idx)
> > > return ret;
> > > }
> > >
> > > +static int vduse_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
> > > + unsigned int asid)
> > > +{
> > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > + struct vduse_dev_msg msg = { 0 };
> > > + int r;
> > > +
> > > + if (dev->api_version < VDUSE_API_VERSION_1 ||
> > > + group >= dev->ngroups || asid >= dev->nas)
> > > + return -EINVAL;
> > > +
> > > + msg.req.type = VDUSE_SET_VQ_GROUP_ASID;
> > > + msg.req.vq_group_asid.group = group;
> > > + msg.req.vq_group_asid.asid = asid;
> > > +
> > > + r = vduse_dev_msg_sync(dev, &msg);
> > > + if (r < 0)
> > > + return r;
> > > +
> > > + vduse_set_group_asid_nomsg(dev, group, asid);
> > > + return 0;
> > > +}
> > > +
> > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > struct vdpa_vq_state *state)
> > > {
> > > @@ -794,13 +845,13 @@ static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > int ret;
> > >
> > > - ret = vduse_domain_set_map(dev->domain, iotlb);
> > > + ret = vduse_domain_set_map(dev->as[asid].domain, iotlb);
> > > if (ret)
> > > return ret;
> > >
> > > - ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> > > + ret = vduse_dev_update_iotlb(dev, asid, 0ULL, ULLONG_MAX);
> > > if (ret) {
> > > - vduse_domain_clear_map(dev->domain, iotlb);
> > > + vduse_domain_clear_map(dev->as[asid].domain, iotlb);
> > > return ret;
> > > }
> > >
> > > @@ -843,6 +894,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
> > > .get_vq_affinity = vduse_vdpa_get_vq_affinity,
> > > .reset = vduse_vdpa_reset,
> > > .set_map = vduse_vdpa_set_map,
> > > + .set_group_asid = vduse_set_group_asid,
> > > .get_vq_map = vduse_get_vq_map,
> > > .free = vduse_vdpa_free,
> > > };
> > > @@ -858,9 +910,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > return;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + mutex_lock(&vdev->domain_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > + mutex_unlock(&vdev->domain_lock);
> > > }
> > >
> > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > @@ -874,9 +927,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > return;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + mutex_lock(&vdev->domain_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > + mutex_unlock(&vdev->domain_lock);
> > > }
> > >
> > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > @@ -886,14 +940,18 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > {
> > > struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > > + dma_addr_t r;
> > >
> > > if (!token.group)
> > > return DMA_MAPPING_ERROR;
> > >
> > > vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > + mutex_lock(&vdev->domain_lock);
> >
> > The mutex_lock can't be used here since the dma ops might be called in
> > atomic context. And I think we can just remove it since creation and
> > deletion operations of the iova domain are guaranteed not to execute
> > concurrently with I/O operations.
> >
>
> That would be great indeed! Can you expand on this, what protects here
> from the moment the two syscalls are issues from userland?
>
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