iommufd/device: Wrap igroup->hwpt and igroup->device_list into attach struct

The igroup->hwpt and igroup->device_list are used to track the hwpt attach
of a group in the RID path. While the coming PASID path also needs such
tracking. To be prepared, wrap igroup->hwpt and igroup->device_list into
attach struct which is allocated per attaching the first device of the
group and freed per detaching the last device of the group.

Link: https://patch.msgid.link/r/20250321171940.7213-8-yi.l.liu@intel.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 2cc3c12d301d68bcd4dc66145ecf75221e096f43..6b4764c2d9af62d73b34ba63738d87c30a3d7069 100644 (file)
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -17,12 +17,17 @@ MODULE_PARM_DESC(
        "Allow IOMMUFD to bind to devices even if the platform cannot isolate "
        "the MSI interrupt window. Enabling this is a security weakness.");
 
+struct iommufd_attach {
+       struct iommufd_hw_pagetable *hwpt;
+       struct list_head device_list;
+};
+
 static void iommufd_group_release(struct kref *kref)
 {
        struct iommufd_group *igroup =
                container_of(kref, struct iommufd_group, ref);
 
-       WARN_ON(igroup->hwpt || !list_empty(&igroup->device_list));
+       WARN_ON(igroup->attach);
 
        xa_cmpxchg(&igroup->ictx->groups, iommu_group_id(igroup->group), igroup,
                   NULL, GFP_KERNEL);
@@ -89,7 +94,6 @@ static struct iommufd_group *iommufd_get_group(struct iommufd_ctx *ictx,
 
        kref_init(&new_igroup->ref);
        mutex_init(&new_igroup->lock);
-       INIT_LIST_HEAD(&new_igroup->device_list);
        new_igroup->sw_msi_start = PHYS_ADDR_MAX;
        /* group reference moves into new_igroup */
        new_igroup->group = group;
@@ -333,7 +337,7 @@ static bool
 iommufd_group_first_attach(struct iommufd_group *igroup, ioasid_t pasid)
 {
        lockdep_assert_held(&igroup->lock);
-       return !igroup->hwpt;
+       return !igroup->attach;
 }
 
 static int
@@ -369,7 +373,7 @@ static bool iommufd_device_is_attached(struct iommufd_device *idev)
 {
        struct iommufd_device *cur;
 
-       list_for_each_entry(cur, &idev->igroup->device_list, group_item)
+       list_for_each_entry(cur, &idev->igroup->attach->device_list, group_item)
                if (cur == idev)
                        return true;
        return false;
@@ -493,19 +497,33 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
        struct iommufd_hwpt_paging *hwpt_paging = find_hwpt_paging(hwpt);
        bool attach_resv = hwpt_paging && pasid == IOMMU_NO_PASID;
        struct iommufd_group *igroup = idev->igroup;
+       struct iommufd_hw_pagetable *old_hwpt;
+       struct iommufd_attach *attach;
        int rc;
 
        mutex_lock(&igroup->lock);
 
-       if (igroup->hwpt && igroup->hwpt != hwpt) {
+       attach = igroup->attach;
+       if (!attach) {
+               attach = kzalloc(sizeof(*attach), GFP_KERNEL);
+               if (!attach) {
+                       rc = -ENOMEM;
+                       goto err_unlock;
+               }
+               INIT_LIST_HEAD(&attach->device_list);
+       }
+
+       old_hwpt = attach->hwpt;
+
+       if (old_hwpt && old_hwpt != hwpt) {
                rc = -EINVAL;
-               goto err_unlock;
+               goto err_free_attach;
        }
 
        if (attach_resv) {
                rc = iommufd_device_attach_reserved_iova(idev, hwpt_paging);
                if (rc)
-                       goto err_unlock;
+                       goto err_free_attach;
        }
 
        /*
@@ -519,15 +537,19 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
                rc = iommufd_hwpt_attach_device(hwpt, idev, pasid);
                if (rc)
                        goto err_unresv;
-               igroup->hwpt = hwpt;
+               attach->hwpt = hwpt;
+               igroup->attach = attach;
        }
        refcount_inc(&hwpt->obj.users);
-       list_add_tail(&idev->group_item, &igroup->device_list);
+       list_add_tail(&idev->group_item, &attach->device_list);
        mutex_unlock(&igroup->lock);
        return 0;
 err_unresv:
        if (attach_resv)
                iopt_remove_reserved_iova(&hwpt_paging->ioas->iopt, idev->dev);
+err_free_attach:
+       if (iommufd_group_first_attach(igroup, pasid))
+               kfree(attach);
 err_unlock:
        mutex_unlock(&igroup->lock);
        return rc;
@@ -537,14 +559,20 @@ struct iommufd_hw_pagetable *
 iommufd_hw_pagetable_detach(struct iommufd_device *idev, ioasid_t pasid)
 {
        struct iommufd_group *igroup = idev->igroup;
-       struct iommufd_hw_pagetable *hwpt = igroup->hwpt;
-       struct iommufd_hwpt_paging *hwpt_paging = find_hwpt_paging(hwpt);
+       struct iommufd_hwpt_paging *hwpt_paging;
+       struct iommufd_hw_pagetable *hwpt;
+       struct iommufd_attach *attach;
 
        mutex_lock(&igroup->lock);
+       attach = igroup->attach;
+       hwpt = attach->hwpt;
+       hwpt_paging = find_hwpt_paging(hwpt);
+
        list_del(&idev->group_item);
-       if (list_empty(&igroup->device_list)) {
+       if (list_empty(&attach->device_list)) {
                iommufd_hwpt_detach_device(hwpt, idev, pasid);
-               igroup->hwpt = NULL;
+               igroup->attach = NULL;
+               kfree(attach);
        }
        if (hwpt_paging && pasid == IOMMU_NO_PASID)
                iopt_remove_reserved_iova(&hwpt_paging->ioas->iopt, idev->dev);
@@ -574,7 +602,7 @@ iommufd_group_remove_reserved_iova(struct iommufd_group *igroup,
 
        lockdep_assert_held(&igroup->lock);
 
-       list_for_each_entry(cur, &igroup->device_list, group_item)
+       list_for_each_entry(cur, &igroup->attach->device_list, group_item)
                iopt_remove_reserved_iova(&hwpt_paging->ioas->iopt, cur->dev);
 }
 
@@ -588,9 +616,10 @@ iommufd_group_do_replace_reserved_iova(struct iommufd_group *igroup,
 
        lockdep_assert_held(&igroup->lock);
 
-       old_hwpt_paging = find_hwpt_paging(igroup->hwpt);
+       old_hwpt_paging = find_hwpt_paging(igroup->attach->hwpt);
        if (!old_hwpt_paging || hwpt_paging->ioas != old_hwpt_paging->ioas) {
-               list_for_each_entry(cur, &igroup->device_list, group_item) {
+               list_for_each_entry(cur,
+                                   &igroup->attach->device_list, group_item) {
                        rc = iopt_table_enforce_dev_resv_regions(
                                &hwpt_paging->ioas->iopt, cur->dev, NULL);
                        if (rc)
@@ -617,27 +646,32 @@ iommufd_device_do_replace(struct iommufd_device *idev, ioasid_t pasid,
        struct iommufd_hwpt_paging *old_hwpt_paging;
        struct iommufd_group *igroup = idev->igroup;
        struct iommufd_hw_pagetable *old_hwpt;
+       struct iommufd_attach *attach;
        unsigned int num_devices;
        int rc;
 
        mutex_lock(&igroup->lock);
 
-       if (igroup->hwpt == NULL) {
+       attach = igroup->attach;
+       if (!attach) {
                rc = -EINVAL;
                goto err_unlock;
        }
 
+       old_hwpt = attach->hwpt;
+
+       WARN_ON(!old_hwpt || list_empty(&attach->device_list));
+
        if (!iommufd_device_is_attached(idev)) {
                rc = -EINVAL;
                goto err_unlock;
        }
 
-       if (hwpt == igroup->hwpt) {
+       if (hwpt == old_hwpt) {
                mutex_unlock(&igroup->lock);
                return NULL;
        }
 
-       old_hwpt = igroup->hwpt;
        if (attach_resv) {
                rc = iommufd_group_do_replace_reserved_iova(igroup, hwpt_paging);
                if (rc)
@@ -653,9 +687,9 @@ iommufd_device_do_replace(struct iommufd_device *idev, ioasid_t pasid,
            (!hwpt_paging || hwpt_paging->ioas != old_hwpt_paging->ioas))
                iommufd_group_remove_reserved_iova(igroup, old_hwpt_paging);
 
-       igroup->hwpt = hwpt;
+       attach->hwpt = hwpt;
 
-       num_devices = list_count_nodes(&igroup->device_list);
+       num_devices = list_count_nodes(&attach->device_list);
        /*
         * Move the refcounts held by the device_list to the new hwpt. Retain a
         * refcount for this thread as the caller will free it.

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 891800948d1a67cab75c25e4f34e5ba880f1f990..5b4d8962166bdec19e29031bd21747f59f9600d9 100644 (file)
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -399,13 +399,14 @@ static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
        refcount_dec(&hwpt->obj.users);
 }
 
+struct iommufd_attach;
+
 struct iommufd_group {
        struct kref ref;
        struct mutex lock;
        struct iommufd_ctx *ictx;
        struct iommu_group *group;
-       struct iommufd_hw_pagetable *hwpt;
-       struct list_head device_list;
+       struct iommufd_attach *attach;
        struct iommufd_sw_msi_maps required_sw_msi;
        phys_addr_t sw_msi_start;
 };