[PATCH 07/17] iommufd: Add/del hwpt to IOAS at alloc/destroy()

Yi Liu
2023-02-09T04:35:01Z

From: Nicolin Chen <nicolinc@nvidia.com>

A hw_pagetable is allocated with an IOAS id, so it was supposed to link
to the IOAS upon its allocation. But, previously with ARM SMMUv3 driver
IOMMUFD fails to add a newly allocated hwpt to the IOAS, because SMMUv3
driver "finalises" an iommu_domain (hwpt->domain) after it attaches to
a device. This was because the existing domain_alloc op doesn't pass in
a dev pointer, so the driver could not know which SMMU device to look
for. Now, IOMMUFD allocates the hwpt->domain using domain_alloc_user op
that passes in the dev pointer. So, there's no need to wait for a device
attachment anymore.

Move iopt_table_add_domain() call, along with the list_add_tail call on
the hwpt_item, to the iommufd_hw_pagetable_alloc() right after a domain
allocation. Accordingly, move iopt_table_remove_domain() and list_del to
the iommufd_hw_pagetable_destroy() routine.

This simplifies the logic in the do_attach/detach(), by reducing the
dependency on the device list and potential locking conundrum with the
coming nesting feature.

Similarly, drop the iopt_table_add/remove_domain() calls, for selftest,
from the iommufd_device_selftest_attach/detach(). Also, allocate hwpts
outside the iommufd_device_selftest_attach() to make it symmetric with
the iommufd_device_selftest_detach().

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 54 ++++---------------------
drivers/iommu/iommufd/hw_pagetable.c | 13 ++++++
drivers/iommu/iommufd/iommufd_private.h | 6 +--
drivers/iommu/iommufd/selftest.c | 16 ++++++--
4 files changed, 35 insertions(+), 54 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 0e5d2bde7b3c..71a8c4f1c4a9 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -311,18 +311,11 @@ static void __iommmufd_device_detach(struct iommufd_device *idev,

mutex_lock(&hwpt->devices_lock);
list_del(&idev->devices_item);
- if (hwpt->ioas != new_ioas)
- mutex_lock(&hwpt->ioas->mutex);
- if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) {
- if (list_empty(&hwpt->devices)) {
- iopt_table_remove_domain(&hwpt->ioas->iopt,
- hwpt->domain);
- list_del(&hwpt->hwpt_item);
- }
- if (detach_group)
- iommu_detach_group(hwpt->domain, idev->group);
- }
+ if (detach_group && !iommufd_hw_pagetable_has_group(hwpt, idev->group))
+ iommu_detach_group(hwpt->domain, idev->group);
+
if (hwpt->ioas != new_ioas) {
+ mutex_lock(&hwpt->ioas->mutex);
iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
mutex_unlock(&hwpt->ioas->mutex);
}
@@ -384,14 +377,6 @@ static int iommufd_device_do_attach(struct iommufd_device *idev,
rc = iommu_group_replace_domain(idev->group, hwpt->domain);
if (rc)
goto out_iova;
-
- if (list_empty(&hwpt->devices)) {
- rc = iopt_table_add_domain(&hwpt->ioas->iopt,
- hwpt->domain);
- if (rc)
- goto out_detach;
- list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
- }
}

/* Replace the cur_hwpt without iommu_detach_group() */
@@ -404,11 +389,6 @@ static int iommufd_device_do_attach(struct iommufd_device *idev,
mutex_unlock(&hwpt->devices_lock);
return 0;

-out_detach:
- if (cur_hwpt)
- iommu_group_replace_domain(idev->group, cur_hwpt->domain);
- else
- iommu_detach_group(hwpt->domain, idev->group);
out_iova:
iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
out_unlock:
@@ -940,35 +920,17 @@ EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD);
* Creating a real iommufd_device is too hard, bypass creating a iommufd_device
* and go directly to attaching a domain.
*/
-struct iommufd_hw_pagetable *
-iommufd_device_selftest_attach(struct iommufd_ctx *ictx,
- struct iommufd_ioas *ioas,
- struct device *mock_dev)
-{
- struct iommufd_hw_pagetable *hwpt;
- int rc;
-
- hwpt = iommufd_hw_pagetable_alloc(ictx, ioas, mock_dev);
- if (IS_ERR(hwpt))
- return hwpt;
-
- rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain);
- if (rc)
- goto out_hwpt;

+int iommufd_device_selftest_attach(struct iommufd_ctx *ictx,
+ struct iommufd_hw_pagetable *hwpt)
+{
refcount_inc(&hwpt->obj.users);
- iommufd_object_finalize(ictx, &hwpt->obj);
- return hwpt;
-
-out_hwpt:
- iommufd_object_abort_and_destroy(ictx, &hwpt->obj);
- return ERR_PTR(rc);
+ return 0;
}

void iommufd_device_selftest_detach(struct iommufd_ctx *ictx,
struct iommufd_hw_pagetable *hwpt)
{
- iopt_table_remove_domain(&hwpt->ioas->iopt, hwpt->domain);
refcount_dec(&hwpt->obj.users);
}
#endif
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 08d963ee38c7..bda21ec737cf 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -11,8 +11,12 @@ void iommufd_hw_pagetable_destroy(struct iommufd_object *obj)
struct iommufd_hw_pagetable *hwpt =
container_of(obj, struct iommufd_hw_pagetable, obj);

+ lockdep_assert_held(&hwpt->ioas->mutex);
+
WARN_ON(!list_empty(&hwpt->devices));

+ iopt_table_remove_domain(&hwpt->ioas->iopt, hwpt->domain);
+ list_del(&hwpt->hwpt_item);
iommu_domain_free(hwpt->domain);
refcount_dec(&hwpt->ioas->obj.users);
mutex_destroy(&hwpt->devices_lock);
@@ -34,6 +38,8 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
struct iommufd_hw_pagetable *hwpt;
int rc;

+ lockdep_assert_held(&ioas->mutex);
+
hwpt = iommufd_object_alloc(ictx, hwpt, IOMMUFD_OBJ_HW_PAGETABLE);
if (IS_ERR(hwpt))
return hwpt;
@@ -53,11 +59,18 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
INIT_LIST_HEAD(&hwpt->devices);
INIT_LIST_HEAD(&hwpt->hwpt_item);
mutex_init(&hwpt->devices_lock);
+ rc = iopt_table_add_domain(&ioas->iopt, hwpt->domain);
+ if (rc)
+ goto out_free_domain;
+ list_add_tail(&hwpt->hwpt_item, &ioas->hwpt_list);
+
/* Pairs with iommufd_hw_pagetable_destroy() */
refcount_inc(&ioas->obj.users);
hwpt->ioas = ioas;
return hwpt;

+out_free_domain:
+ iommu_domain_free(hwpt->domain);
out_abort:
iommufd_object_abort(ictx, &hwpt->obj);
return ERR_PTR(rc);
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 7748117e36f9..604ad29f87b8 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -278,10 +278,8 @@ void iopt_remove_access(struct io_pagetable *iopt,
void iommufd_access_destroy_object(struct iommufd_object *obj);

#ifdef CONFIG_IOMMUFD_TEST
-struct iommufd_hw_pagetable *
-iommufd_device_selftest_attach(struct iommufd_ctx *ictx,
- struct iommufd_ioas *ioas,
- struct device *mock_dev);
+int iommufd_device_selftest_attach(struct iommufd_ctx *ictx,
+ struct iommufd_hw_pagetable *hwpt);
void iommufd_device_selftest_detach(struct iommufd_ctx *ictx,
struct iommufd_hw_pagetable *hwpt);
struct device *iommufd_selftest_obj_to_dev(struct iommufd_object *obj);
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index 5013c8757f4b..5f841d1d9e96 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -311,22 +311,30 @@ static int iommufd_test_mock_domain(struct iommufd_ucmd *ucmd,
sobj->idev.mock_dev.bus = &mock_bus;
sobj->idev.mock_dev.iommu = &iommu;

- hwpt = iommufd_device_selftest_attach(ucmd->ictx, ioas,
- &sobj->idev.mock_dev);
+ hwpt = iommufd_hw_pagetable_alloc(ucmd->ictx, ioas,
+ &sobj->idev.mock_dev);
if (IS_ERR(hwpt)) {
rc = PTR_ERR(hwpt);
- goto out_sobj;
+ goto out_unlock;
}
sobj->idev.hwpt = hwpt;

+ rc = iommufd_device_selftest_attach(ucmd->ictx, hwpt);
+ if (rc)
+ goto out_free_hwpt;
+
/* Userspace must destroy both of these IDs to destroy the object */
cmd->mock_domain.out_hwpt_id = hwpt->obj.id;
cmd->mock_domain.out_device_id = sobj->obj.id;
iommufd_object_finalize(ucmd->ictx, &sobj->obj);
+ iommufd_object_finalize(ucmd->ictx, &hwpt->obj);
iommufd_put_object(&ioas->obj);
return iommufd_ucmd_respond(ucmd, sizeof(*cmd));

-out_sobj:
+out_free_hwpt:
+ iommufd_object_abort_and_destroy(ucmd->ictx, &hwpt->obj);
+out_unlock:
+ mutex_unlock(&ioas->mutex);
iommufd_object_abort(ucmd->ictx, &sobj->obj);
out_ioas:
iommufd_put_object(&ioas->obj);
--
2.34.1