Re: [PATCH v3 5/6] vduse: add vq group asid support

Jason Wang
2025-09-22T01:50:14Z

On Fri, Sep 19, 2025 at 5:34 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.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
> 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 | 327 ++++++++++++++++++++---------
> include/uapi/linux/vduse.h | 51 ++++-
> 2 files changed, 281 insertions(+), 97 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 6fdabc3c910e..c6c70cfd4887 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -42,6 +42,7 @@
>
> #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)
> @@ -89,7 +90,14 @@ 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;
> };
>
> @@ -97,7 +105,7 @@ 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;
> @@ -125,9 +133,8 @@ 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;
> rwlock_t domain_lock;
> };
> @@ -324,7 +331,7 @@ 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 };
> @@ -333,8 +340,14 @@ 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);
> }
> @@ -446,14 +459,29 @@ 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)
> +{
> + write_lock(&dev->domain_lock);
> + dev->groups[group].as = &dev->as[asid];
> + write_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);
>
> @@ -639,6 +667,29 @@ 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)
> {
> @@ -810,13 +861,13 @@ 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;
> }
>
> @@ -859,6 +910,7 @@ 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,
> };
> @@ -874,9 +926,10 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> return;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> -
> + read_lock(&vdev->domain_lock);

This introduce atomic operation in the datapath, I wonder if we can
switch to use RCU instead.

> + domain = token.group->as->domain;
> vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> + read_unlock(&vdev->domain_lock);
> }
>
> static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> @@ -890,9 +943,10 @@ static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> return;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> -
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> + read_unlock(&vdev->domain_lock);
> }
>
> static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> @@ -902,14 +956,18 @@ 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;
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> + r = vduse_domain_map_page(domain, page, offset, size, dir, attrs);
> + read_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,
> @@ -923,9 +981,10 @@ 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);
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> + vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
> + read_unlock(&vdev->domain_lock);
> }
>
> static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
> @@ -934,21 +993,21 @@ static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
> struct vduse_dev *vdev;
> struct vduse_iova_domain *domain;
> unsigned long iova;
> - void *addr;
> + void *addr = NULL;

Nit: if we stick to no NULL assignment we can save some lines of code below.

>
> *dma_addr = DMA_MAPPING_ERROR;
> if (!token.group)
> return NULL;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> + read_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;
>
> + read_unlock(&vdev->domain_lock);
> return addr;
> }
>
> @@ -963,23 +1022,28 @@ static void vduse_dev_free_coherent(union virtio_map token, size_t size,
> return;
>
> vdev = token.group->dev;
> - domain = vdev->domain;
> -
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
> + read_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;
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> + bounce_size = domain->bounce_size;
> + read_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)
> @@ -993,14 +1057,18 @@ 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;
> + read_lock(&vdev->domain_lock);
> + domain = token.group->as->domain;
> + bounce_size = domain->bounce_size;
> + read_unlock(&vdev->domain_lock);
>
> - return domain->bounce_size;
> + return bounce_size;
> }
>
> static const struct virtio_map_ops vduse_map_ops = {
> @@ -1140,39 +1208,40 @@ 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;
> @@ -1180,14 +1249,14 @@ 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;
> @@ -1211,7 +1280,7 @@ 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;
> @@ -1224,7 +1293,7 @@ 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);
> @@ -1235,7 +1304,7 @@ 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;
> }
>
> @@ -1267,47 +1336,66 @@ 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;
>
> read_lock(&dev->domain_lock);
> - if (!dev->domain) {
> + asid = array_index_nospec(entry.asid, dev->nas);
> + if (!dev->as[asid].domain) {
> read_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);
> read_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) {
> 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;
> }
> @@ -1452,6 +1540,7 @@ 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)))
> @@ -1459,17 +1548,21 @@ 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)

This allows umem.asid to be set even with version < 1?

> break;
>
> write_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);
> write_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)))
> @@ -1477,10 +1570,15 @@ 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)

And here?

> break;
> +
> write_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);
> write_unlock(&dev->domain_lock);
> break;
> @@ -1488,6 +1586,7 @@ 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)))
> @@ -1501,23 +1600,31 @@ 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;
> +
> read_lock(&dev->domain_lock);
> - if (!dev->domain) {
> + asid = array_index_nospec(info.asid, dev->nas);
> + if (!dev->as[asid].domain) {
> read_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);
> read_unlock(&dev->domain_lock);
> if (!map)
> break;
> @@ -1542,8 +1649,10 @@ static int vduse_dev_release(struct inode *inode, struct file *file)
> struct vduse_dev *dev = file->private_data;
>
> write_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);
> write_unlock(&dev->domain_lock);
> spin_lock(&dev->msg_lock);
> /* Make sure the inflight messages can processed after reconncection */
> @@ -1762,7 +1871,6 @@ static struct vduse_dev *vduse_dev_create(void)
> return NULL;
>
> mutex_init(&dev->lock);
> - mutex_init(&dev->mem_lock);
> rwlock_init(&dev->domain_lock);
> spin_lock_init(&dev->msg_lock);
> INIT_LIST_HEAD(&dev->send_list);
> @@ -1813,8 +1921,11 @@ 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);
> @@ -1861,13 +1972,18 @@ 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 > VDUSE_DEV_MAX_GROUPS)
> return false;
>
> + if (api_version >= VDUSE_API_VERSION_1 &&
> + config->nas > VDUSE_DEV_MAX_AS)
> + return false;

Nit: is this better to have:

if (api_version >= VDUSE_API_VERSION_1) {
if () return false;
if () return false;
}

?

> +
> if (config->vq_align > PAGE_SIZE)
> return false;
>
> @@ -1931,7 +2047,8 @@ static ssize_t bounce_size_store(struct device *device,
>
> ret = -EPERM;
> write_lock(&dev->domain_lock);
> - if (dev->domain)
> + /* Assuming that if the first domain is allocated, all are allocated */

I don't fully understand the comment here.

> + if (dev->as[0].domain)
> goto unlock;
>
> ret = kstrtouint(buf, 10, &bounce_size);
> @@ -1992,6 +2109,13 @@ 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 < 1) ? 1 : (config->nas ?: 1);
> + 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;
> @@ -2028,6 +2152,8 @@ 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);
> @@ -2153,7 +2279,7 @@ 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);
>
> @@ -2182,11 +2308,20 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
> return ret;
>
> write_lock(&dev->domain_lock);
> - if (!dev->domain)
> - dev->domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
> - dev->bounce_size);
> + ret = 0;
> +
> + for (int i = 0; i < dev->nas; ++i) {
> + dev->as[i].domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
> + dev->bounce_size);

Per discussion previously, should we divide bounce_size here?

> + if (!dev->as[i].domain) {
> + ret = -ENOMEM;
> + for (int j = 0; j < i; ++j)
> + vduse_domain_destroy(dev->as[j].domain);
> + }
> + }
> +
> write_unlock(&dev->domain_lock);
> - if (!dev->domain) {
> + if (ret == -ENOMEM) {
> put_device(&dev->vdev->vdpa.dev);
> return -ENOMEM;
> }
> @@ -2195,8 +2330,12 @@ static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
> if (ret) {
> put_device(&dev->vdev->vdpa.dev);
> write_lock(&dev->domain_lock);
> - vduse_domain_destroy(dev->domain);
> - dev->domain = NULL;
> + for (int i = 0; i < dev->nas; i++) {
> + if (dev->as[i].domain) {
> + vduse_domain_destroy(dev->as[i].domain);
> + dev->as[i].domain = NULL;
> + }
> + }
> write_unlock(&dev->domain_lock);
> return ret;
> }
> diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
> index a3d51cf6df3a..da73c3f2c280 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 - virtqueue group
> + @ @group: Index of the virtqueue group

I see double "@".

> + * @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 +376,9 @@ struct vduse_dev_request {
> struct vduse_vq_state vq_state;
> struct vduse_dev_status s;
> struct vduse_iova_range iova;
> + /* Following members 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
>

Thanks