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Message-ID: <CACGkMEu1Lxun4aPza+kw7KrmLZJkfmW22KQNxbch+YhiTMkJZg@mail.gmail.com>
Date: Tue, 23 Dec 2025 09:11:09 +0800
From: Jason Wang <jasowang@...hat.com>
To: Eugenio Perez Martin <eperezma@...hat.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Maxime Coquelin <mcoqueli@...hat.com>,
Laurent Vivier <lvivier@...hat.com>, virtualization@...ts.linux.dev,
linux-kernel@...r.kernel.org, Stefano Garzarella <sgarzare@...hat.com>,
Yongji Xie <xieyongji@...edance.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Cindy Lu <lulu@...hat.com>
Subject: Re: [PATCH v10 7/8] vduse: add vq group asid support
On Thu, Dec 18, 2025 at 9:11 PM Eugenio Perez Martin
<eperezma@...hat.com> wrote:
>
> On Thu, Dec 18, 2025 at 7:45 AM Jason Wang <jasowang@...hat.com> wrote:
> >
> > On Wed, Dec 17, 2025 at 7:24 PM Eugenio Pérez <eperezma@...hat.com> wrote:
> > >
> > > Add support for assigning Address Space Identifiers (ASIDs) to each VQ
> > > group. This enables mapping each group into a distinct memory space.
> > >
> > > The vq group to ASID association is protected by a rwlock now. But the
> > > mutex domain_lock keeps protecting the domains of all ASIDs, as some
> > > operations like the one related with the bounce buffer size still
> > > requires to lock all the ASIDs.
> > >
> > > Signed-off-by: Eugenio Pérez <eperezma@...hat.com>
> > >
> > > ---
> > > Future improvements can include performance optimizations on top could
> > > move to per-ASID locks, or hardening by tracking ASID or ASID hashes on
> > > unused bits of the DMA address.
> > >
> > > Tested virtio_vdpa by adding manually two threads in vduse_set_status:
> > > one of them modifies the vq group 0 ASID and the other one map and unmap
> > > memory continuously. After a while, the two threads stop and the usual
> > > work continues.
> > >
> > > Tested with vhost_vdpa by migrating a VM while ping on OVS+VDUSE. A few
> > > workaround were needed in some parts:
> > > * Do not enable CVQ before data vqs in QEMU, as VDUSE does not forward
> > > the enable message to the userland device. This will be solved in the
> > > future.
> > > * Share the suspended state between all vhost devices in QEMU:
> > > https://lists.nongnu.org/archive/html/qemu-devel/2025-11/msg02947.html
> > > * Implement a fake VDUSE suspend vdpa operation callback that always
> > > returns true in the kernel. DPDK suspend the device at the first
> > > GET_VRING_BASE.
> > > * Remove the CVQ blocker in ASID.
> > >
> > > ---
> > > v10:
> > > * Back to rwlock version so stronger locks are used.
> > > * Take out allocations from rwlock.
> > > * Forbid changing ASID of a vq group after DRIVER_OK (Jason)
> > > * Remove bad fetching again of domain variable in
> > > vduse_dev_max_mapping_size (Yongji).
> > > * Remove unused vdev definition in vdpa map_ops callbacks (kernel test
> > > robot).
> > >
> > > v9:
> > > * Replace mutex with rwlock, as the vdpa map_ops can run from atomic
> > > context.
> > >
> > > 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 | 366 +++++++++++++++++++----------
> > > include/uapi/linux/vduse.h | 53 ++++-
> > > 2 files changed, 295 insertions(+), 124 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > index 767abcb7e375..786ab2378825 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 +87,15 @@ struct vduse_umem {
> > > struct mm_struct *mm;
> > > };
> > >
> > > +struct vduse_as {
> > > + struct vduse_iova_domain *domain;
> > > + struct vduse_umem *umem;
> > > + struct mutex mem_lock;
> >
> > Not related to this patch. But If I was not wrong we have 1:1 mapping
> > between domain and as. If this is true, can we use bounce_lock instead
> > of a new mem_lock? Since I see mem_lock is only used for synchronizing
> > umem reg/degreg which has been synchronized with domain rwlock.
> >
>
> I think you're right, but they work at different levels at the moment.
> The mem_lock is at vduse_dev and also protect the umem pointer, and
> bounce_lock is at iova_domain.c .
>
> Maybe the right thing to do is to move umem in iova_domain. Yongji
> Xie, what do you think?
>
> > > +};
> > > +
> > > struct vduse_vq_group {
> > > + rwlock_t as_lock;
> > > + struct vduse_as *as; /* Protected by as_lock */
> > > struct vduse_dev *dev;
> > > };
> > >
> > > @@ -94,7 +103,7 @@ 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 +131,8 @@ 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 +322,7 @@ 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 +331,14 @@ 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 +450,29 @@ 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->groups[group].as_lock);
> > > + dev->groups[group].as = &dev->as[asid];
> > > + write_unlock(&dev->groups[group].as_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);
> >
> > Btw, I see this:
> >
> > void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain)
> > {
> > if (!domain->bounce_map)
> > return;
> >
> > spin_lock(&domain->iotlb_lock);
> > if (!domain->bounce_map)
> > goto unlock;
> >
> >
> > The counbe_map is checked twice, let's fix that.
> >
>
> Double checked locking to avoid taking the lock?
I don't know, but I think we don't care too much about the performance
of vduse_domain_reset_bounce_map().
> I don't think it is
> worth it to keep it as it is not in the hot path anyway. But that
> would also be another patch independent of this series, isn't it?
Yes, it's another independent issue I just found when reviewing this patch.
>
> > > + }
> > > +
> > > + for (i = 0; i < dev->ngroups; i++)
> > > + vduse_set_group_asid_nomsg(dev, i, 0);
> >
> > Note that this function still does:
> >
> > vq->vq_group = 0;
> >
> > Which is wrong.
> >
>
> Right, removing it for the next version. Thanks for the catch!
>
> > >
> > > down_write(&dev->rwsem);
> > >
> > > @@ -623,6 +652,30 @@ 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 ||
> > > + dev->status & VIRTIO_CONFIG_S_DRIVER_OK)
> > > + return -EINVAL;
> >
> > If we forbid setting group asid for !DRIVER_OK, why do we still need a
> > rwlock?
>
> virtio_map_ops->alloc is still called before DRIVER_OK to allocate the
> vrings in the bounce buffer, for example. If you're ok with that I'm
> ok with removing the lock, as all the calls are issued by the driver
> setup process anyway. Or just to keep it for alloc?
I see, then I think we need to keep that. The reason is that there's
no guarantee that the alloc() must be called before DRIVER_OK.
>
> Anyway, I think I misunderstood your comment from [1] then.
>
> > All we need to do is to synchronize set_group_asid() with
> > set_status()/reset()?
> >
>
> That's also a good one. There is no synchronization if one thread call
> reset and then the device is set up from another thread. As all this
> situation is still hypothetical because virtio_vdpa does not support
> set_group_asid,
Right.
> and vhost one is already protected by vhost lock, do
> we need it?
Let's add a TODO in the code.
>
> > Or if you want to synchronize map ops with set_status() that looks
> > like an independent thing (hardening).
> >
> > > +
> > > + 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);
> >
> > I'm not sure this has been discussed before, but I think it would be
> > better to introduce a new ioctl to get group -> as mapping. This helps
> > to avoid vduse_dev_msg_sync() as much as possible. And it doesn't
> > require the userspace to poll vduse fd before DRIVER_OK.
> >
>
> I'm fine with that, but how do we communicate that they have changed?
Since we forbid changing the group->as mapping after DRIVER_OK,
userspace just needs to use that ioctl once after DRIVER_OK.
> Or how to communicate to the driver that the device does not accept
> the assignment of the ASID to the group?
See above.
>
> > > + return 0;
> > > +}
> > > +
> > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> > > struct vdpa_vq_state *state)
> > > {
> > > @@ -794,13 +847,13 @@ 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 +896,7 @@ 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,
> > > };
> > > @@ -851,32 +905,30 @@ static void vduse_dev_sync_single_for_device(union virtio_map token,
> > > dma_addr_t dma_addr, size_t size,
> > > enum dma_data_direction dir)
> > > {
> > > - struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > >
> > > if (!token.group)
> > > return;
> > >
> > > - vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + read_lock(&token.group->as_lock);
> >
> > I think we could optimize the lock here. E.g when nas is 1, we don't
> > need any lock in fact.
> >
>
> Good point! Not taking the lock in that case for the next version, thanks!
>
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir);
> > > + read_unlock(&token.group->as_lock);
> > > }
> > >
> > > static void vduse_dev_sync_single_for_cpu(union virtio_map token,
> > > dma_addr_t dma_addr, size_t size,
> > > enum dma_data_direction dir)
> > > {
> > > - struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > >
> > > if (!token.group)
> > > return;
> > >
> > > - vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + read_lock(&token.group->as_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir);
> > > + read_unlock(&token.group->as_lock);
> > > }
> > >
> > > static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > @@ -884,38 +936,38 @@ static dma_addr_t vduse_dev_map_page(union virtio_map token, struct page *page,
> > > enum dma_data_direction dir,
> > > unsigned long attrs)
> > > {
> > > - 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(&token.group->as_lock);
> > > + domain = token.group->as->domain;
> > > + r = vduse_domain_map_page(domain, page, offset, size, dir, attrs);
> > > + read_unlock(&token.group->as_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,
> > > size_t size, enum dma_data_direction dir,
> > > unsigned long attrs)
> > > {
> > > - struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > >
> > > if (!token.group)
> > > return;
> > >
> > > - vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > - return vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
> > > + read_lock(&token.group->as_lock);
> > > + domain = token.group->as->domain;
> > > + vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
> > > + read_unlock(&token.group->as_lock);
> > > }
> > >
> > > static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
> > > dma_addr_t *dma_addr, gfp_t flag)
> > > {
> > > - struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > > unsigned long iova;
> > > void *addr;
> > > @@ -928,18 +980,21 @@ static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
> > > if (!addr)
> > > return NULL;
> > >
> > > - vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > + *dma_addr = (dma_addr_t)iova;
> >
> > Any reason we need to touch *dma_addr here? It might trigger UBSAN/KMSAN.
> >
>
> No, this is a leftover. I'm fixing it for the next version. Thanks!
>
> > > + read_lock(&token.group->as_lock);
> > > + domain = token.group->as->domain;
> > > addr = vduse_domain_alloc_coherent(domain, size,
> > > (dma_addr_t *)&iova, addr);
> > > if (!addr)
> > > goto err;
> > >
> > > *dma_addr = (dma_addr_t)iova;
> > > + read_unlock(&token.group->as_lock);
> > >
> > > return addr;
> > >
> > > err:
> > > + read_unlock(&token.group->as_lock);
> > > free_pages_exact(addr, size);
> > > return NULL;
> > > }
> > > @@ -948,31 +1003,30 @@ static void vduse_dev_free_coherent(union virtio_map token, size_t size,
> > > void *vaddr, dma_addr_t dma_addr,
> > > unsigned long attrs)
> > > {
> > > - struct vduse_dev *vdev;
> > > struct vduse_iova_domain *domain;
> > >
> > > if (!token.group)
> > > return;
> > >
> > > - vdev = token.group->dev;
> > > - domain = vdev->domain;
> > > -
> > > + read_lock(&token.group->as_lock);
> > > + domain = token.group->as->domain;
> > > vduse_domain_free_coherent(domain, size, dma_addr, attrs);
> > > + read_unlock(&token.group->as_lock);
> > > free_pages_exact(vaddr, size);
> > > }
> > >
> > > 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(&token.group->as_lock);
> > > + bounce_size = token.group->as->domain->bounce_size;
> > > + read_unlock(&token.group->as_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)
> > > @@ -984,16 +1038,16 @@ static int vduse_dev_mapping_error(union virtio_map token, dma_addr_t dma_addr)
> > >
> > > 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(&token.group->as_lock);
> > > + bounce_size = token.group->as->domain->bounce_size;
> > > + read_unlock(&token.group->as_lock);
> > >
> > > - return domain->bounce_size;
> > > + return bounce_size;
> > > }
> > >
> > > static const struct virtio_map_ops vduse_map_ops = {
> > > @@ -1133,39 +1187,40 @@ 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;
> > > @@ -1173,14 +1228,14 @@ 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;
> > > @@ -1204,7 +1259,7 @@ 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;
> > > @@ -1217,7 +1272,7 @@ 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);
> > > @@ -1228,7 +1283,7 @@ 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;
> > > }
> > >
> > > @@ -1260,47 +1315,66 @@ 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;
> >
> > Nit: if we stick entry and do copy_from_user() twice it might save
> > lots of unnecessary changes.
> >
>
> I'm happy to move to something else but most of the changes happen
> because of s/entry/entry.v1/ . If we stick with just vduse_iotlb_entry
> and a separate asid variable, we also need to duplicate the
> copy_from_user [2].
>
> > > 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;
> > > }
> > > @@ -1445,6 +1519,7 @@ 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)))
> > > @@ -1452,17 +1527,21 @@ 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)))
> > > @@ -1470,10 +1549,15 @@ 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;
> > > @@ -1481,6 +1565,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> > > case VDUSE_IOTLB_GET_INFO: {
> >
> > Btw I see this:
> >
> > dev->vqs[index]->vq_group = config.group;
> >
> > In VDUSE_VQ_SETUP:
> >
> > I wonder what's the reason that it is not a part of CREATE_DEV? I
> > meant it might be racy if DMA happens between CREATE_DEV and
> > VDUSE_VQ_SETUP.
> >
>
> The reason the vq index -> vq group association cannot be part of
> device creation is that we need CVQ to be isolated for live migration,
> but the device doesn't know the CVQ index at the CREATE_DEV time, only
> after the feature negotiation happens [3].
Exactly, the cvq index is changed.
>
> [1] https://lore.kernel.org/lkml/CACGkMEvRQ86dYeY3Enqoj1vkSpefU3roq4XGS+y5B5kmsXEkYg@mail.gmail.com/
> [2] https://lore.kernel.org/lkml/CACGkMEtszQeZLTegxEbjODYxu-giTvURu=pKj4kYTHQYoKOzkQ@mail.gmail.com
> [3] https://lore.kernel.org/lkml/CAJaqyWcvHx7kwcTceN2jazT0nKNo1r5zdzqWHqpxdna-kCS1RA@mail.gmail.com
I see, but a question. What happens if there's a DMA between
CREATE_DEV and VDUSE_VQ_SETUP. If we can find ways to forbid this (or
it has been forbidden), we are probably fine.
>
> > > struct vduse_iova_info info;
> > > struct vhost_iotlb_map *map;
> > > + u32 asid;
> > >
> > > ret = -EFAULT;
> > > if (copy_from_user(&info, argp, sizeof(info)))
> > > @@ -1494,23 +1579,31 @@ 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;
> > > @@ -1535,8 +1628,10 @@ 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 */
> > > @@ -1755,7 +1850,6 @@ 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);
> > > @@ -1806,8 +1900,11 @@ 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);
> > > @@ -1854,12 +1951,17 @@ 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;
> > > @@ -1924,7 +2026,8 @@ 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;
> >
> > Not for this patch but I don't understand why we need to check dev->domain here.
> >
>
> I guess you need to know the bounce size before you allocate the
> domain. To make shrink logic for it seems not to be worth it, but
> maybe I'm missing something.
Right.
Thanks
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