[PATCH v6 07/10] iommufd: Add a nested HW pagetable object

Yi Liu
2023-10-24T15:10:25Z

From: Nicolin Chen <nicolinc@nvidia.com>

IOMMU_HWPT_ALLOC already supports iommu_domain allocation for usersapce.
But it can only allocate a hw_pagetable that associates to a given IOAS,
i.e. only a kernel-managed hw_pagetable of IOMMUFD_OBJ_HWPT_PAGING type.

IOMMU drivers can now support user-managed hw_pagetables, for two-stage
translation use cases that require user data input from the user space.

Add a new IOMMUFD_OBJ_HWPT_NESTED type with its abort/destroy(). Pair it
with a new iommufd_hwpt_nested structure and its to_hwpt_nested() helper.
Update the to_hwpt_paging() helper, so a NESTED-type hw_pagetable can be
handled in the callers, for example iommufd_hw_pagetable_enforce_rr().

Screen the inputs including the parent PAGING-type hw_pagetable that has
a need of a new nest_parent flag in the iommufd_hwpt_paging structure.

Extend the IOMMU_HWPT_ALLOC ioctl to accept an IOMMU driver specific data
input. Also, update the @pt_id to accept hwpt_id too besides an ioas_id.
Then, use them to allocate a hw_pagetable of IOMMUFD_OBJ_HWPT_NESTED type
using the iommufd_hw_pagetable_alloc_nested() allocator.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Co-developed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 1 +
drivers/iommu/iommufd/hw_pagetable.c | 105 ++++++++++++++++++++++++
drivers/iommu/iommufd/iommufd_private.h | 29 +++++--
drivers/iommu/iommufd/main.c | 4 +
include/uapi/linux/iommufd.h | 23 +++++-
5 files changed, 154 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 902288ca910d..6dbd58a718e4 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -627,6 +627,7 @@ static int iommufd_device_change_pt(struct iommufd_device *idev, u32 *pt_id,
return PTR_ERR(pt_obj);

switch (pt_obj->type) {
+ case IOMMUFD_OBJ_HWPT_NESTED:
case IOMMUFD_OBJ_HWPT_PAGING: {
struct iommufd_hw_pagetable *hwpt =
container_of(pt_obj, struct iommufd_hw_pagetable, obj);
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index fbe09e2473bc..d41428a0fdc2 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -44,6 +44,22 @@ void iommufd_hwpt_paging_abort(struct iommufd_object *obj)
iommufd_hwpt_paging_destroy(obj);
}

+void iommufd_hwpt_nested_destroy(struct iommufd_object *obj)
+{
+ struct iommufd_hwpt_nested *hwpt_nested =
+ container_of(obj, struct iommufd_hwpt_nested, common.obj);
+
+ if (hwpt_nested->common.domain)
+ iommu_domain_free(hwpt_nested->common.domain);
+
+ refcount_dec(&hwpt_nested->parent->common.obj.users);
+}
+
+void iommufd_hwpt_nested_abort(struct iommufd_object *obj)
+{
+ iommufd_hwpt_nested_destroy(obj);
+}
+
static int
iommufd_hwpt_paging_enforce_cc(struct iommufd_hwpt_paging *hwpt_paging)
{
@@ -107,6 +123,7 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
/* Pairs with iommufd_hw_pagetable_destroy() */
refcount_inc(&ioas->obj.users);
hwpt_paging->ioas = ioas;
+ hwpt_paging->nest_parent = flags & IOMMU_HWPT_ALLOC_NEST_PARENT;

if (ops->domain_alloc_user) {
hwpt->domain = ops->domain_alloc_user(idev->dev, flags,
@@ -170,6 +187,73 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
return ERR_PTR(rc);
}

+/**
+ * iommufd_hwpt_nested_alloc() - Get a NESTED iommu_domain for a device
+ * @ictx: iommufd context
+ * @parent: Parent PAGING-type hwpt to associate the domain with
+ * @idev: Device to get an iommu_domain for
+ * @flags: Flags from userspace
+ * @user_data: user_data pointer. Must be valid
+ *
+ * Allocate a new iommu_domain (must be IOMMU_DOMAIN_NESTED) and return it as
+ * a NESTED hw_pagetable. The given parent PAGING-type hwpt must be capable of
+ * being a parent.
+ */
+static struct iommufd_hwpt_nested *
+iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
+ struct iommufd_hwpt_paging *parent,
+ struct iommufd_device *idev, u32 flags,
+ const struct iommu_user_data *user_data)
+{
+ const struct iommu_ops *ops = dev_iommu_ops(idev->dev);
+ struct iommufd_hwpt_nested *hwpt_nested;
+ struct iommufd_hw_pagetable *hwpt;
+ int rc;
+
+ if (flags != 0)
+ return ERR_PTR(-EOPNOTSUPP);
+ if (!user_data)
+ return ERR_PTR(-EINVAL);
+ if (user_data->type == IOMMU_HWPT_DATA_NONE)
+ return ERR_PTR(-EINVAL);
+ if (parent->auto_domain)
+ return ERR_PTR(-EINVAL);
+ if (!parent->nest_parent)
+ return ERR_PTR(-EINVAL);
+
+ if (!ops->domain_alloc_user)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ hwpt_nested = __iommufd_object_alloc(ictx, hwpt_nested,
+ IOMMUFD_OBJ_HWPT_NESTED,
+ common.obj);
+ if (IS_ERR(hwpt_nested))
+ return ERR_CAST(hwpt_nested);
+ hwpt = &hwpt_nested->common;
+
+ refcount_inc(&parent->common.obj.users);
+ hwpt_nested->parent = parent;
+
+ hwpt->domain = ops->domain_alloc_user(idev->dev, 0,
+ parent->common.domain,
+ user_data);
+ if (IS_ERR(hwpt->domain)) {
+ rc = PTR_ERR(hwpt->domain);
+ hwpt->domain = NULL;
+ goto out_abort;
+ }
+
+ if (WARN_ON_ONCE(hwpt->domain->type != IOMMU_DOMAIN_NESTED)) {
+ rc = -EINVAL;
+ goto out_abort;
+ }
+ return hwpt_nested;
+
+out_abort:
+ iommufd_object_abort_and_destroy(ictx, &hwpt->obj);
+ return ERR_PTR(rc);
+}
+
int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
{
struct iommu_hwpt_alloc *cmd = ucmd->cmd;
@@ -195,6 +279,10 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
if (pt_obj->type == IOMMUFD_OBJ_IOAS) {
struct iommufd_hwpt_paging *hwpt_paging;

+ if (cmd->data_type != IOMMU_HWPT_DATA_NONE) {
+ rc = -EINVAL;
+ goto out_put_pt;
+ }
ioas = container_of(pt_obj, struct iommufd_ioas, obj);
mutex_lock(&ioas->mutex);
hwpt_paging = iommufd_hwpt_paging_alloc(ucmd->ictx, ioas, idev,
@@ -204,6 +292,23 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
goto out_unlock;
}
hwpt = &hwpt_paging->common;
+ } else if (pt_obj->type == IOMMUFD_OBJ_HWPT_PAGING) {
+ const struct iommu_user_data user_data = {
+ .type = cmd->data_type,
+ .uptr = u64_to_user_ptr(cmd->data_uptr),
+ .len = cmd->data_len,
+ };
+ struct iommufd_hwpt_nested *hwpt_nested;
+ struct iommufd_hwpt_paging *parent;
+
+ parent = container_of(pt_obj, typeof(*parent), common.obj);
+ hwpt_nested = iommufd_hwpt_nested_alloc(ucmd->ictx, parent, idev,
+ cmd->flags, &user_data);
+ if (IS_ERR(hwpt_nested)) {
+ rc = PTR_ERR(hwpt_nested);
+ goto out_unlock;
+ }
+ hwpt = &hwpt_nested->common;
} else {
rc = -EINVAL;
goto out_put_pt;
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 6493fcdad1b7..6fdad56893af 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -124,6 +124,7 @@ enum iommufd_object_type {
IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE,
IOMMUFD_OBJ_DEVICE,
IOMMUFD_OBJ_HWPT_PAGING,
+ IOMMUFD_OBJ_HWPT_NESTED,
IOMMUFD_OBJ_IOAS,
IOMMUFD_OBJ_ACCESS,
#ifdef CONFIG_IOMMUFD_TEST
@@ -255,10 +256,16 @@ struct iommufd_hwpt_paging {
bool auto_domain : 1;
bool enforce_cache_coherency : 1;
bool msi_cookie : 1;
+ bool nest_parent : 1;
/* Head at iommufd_ioas::hwpt_list */
struct list_head hwpt_item;
};

+struct iommufd_hwpt_nested {
+ struct iommufd_hw_pagetable common;
+ struct iommufd_hwpt_paging *parent;
+};
+
static inline bool hwpt_is_paging(struct iommufd_hw_pagetable *hwpt)
{
return hwpt->obj.type == IOMMUFD_OBJ_HWPT_PAGING;
@@ -290,18 +297,28 @@ struct iommufd_hw_pagetable *
iommufd_hw_pagetable_detach(struct iommufd_device *idev);
void iommufd_hwpt_paging_destroy(struct iommufd_object *obj);
void iommufd_hwpt_paging_abort(struct iommufd_object *obj);
+void iommufd_hwpt_nested_destroy(struct iommufd_object *obj);
+void iommufd_hwpt_nested_abort(struct iommufd_object *obj);
int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd);

static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
struct iommufd_hw_pagetable *hwpt)
{
- struct iommufd_hwpt_paging *hwpt_paging = to_hwpt_paging(hwpt);
+ if (WARN_ON(hwpt->obj.type != IOMMUFD_OBJ_HWPT_PAGING &&
+ hwpt->obj.type != IOMMUFD_OBJ_HWPT_NESTED))
+ return;

- lockdep_assert_not_held(&hwpt_paging->ioas->mutex);
- if (hwpt_paging->auto_domain)
- iommufd_object_deref_user(ictx, &hwpt->obj);
- else
- refcount_dec(&hwpt->obj.users);
+ if (hwpt->obj.type == IOMMUFD_OBJ_HWPT_PAGING) {
+ struct iommufd_hwpt_paging *hwpt_paging = to_hwpt_paging(hwpt);
+
+ lockdep_assert_not_held(&hwpt_paging->ioas->mutex);
+
+ if (hwpt_paging->auto_domain) {
+ iommufd_object_deref_user(ictx, &hwpt->obj);
+ return;
+ }
+ }
+ refcount_dec(&hwpt->obj.users);
}

struct iommufd_group {
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index ab6675a7f6b4..45b9d40773b1 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -492,6 +492,10 @@ static const struct iommufd_object_ops iommufd_object_ops[] = {
.destroy = iommufd_hwpt_paging_destroy,
.abort = iommufd_hwpt_paging_abort,
},
+ [IOMMUFD_OBJ_HWPT_NESTED] = {
+ .destroy = iommufd_hwpt_nested_destroy,
+ .abort = iommufd_hwpt_nested_abort,
+ },
#ifdef CONFIG_IOMMUFD_TEST
[IOMMUFD_OBJ_SELFTEST] = {
.destroy = iommufd_selftest_destroy,
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index fccc6315a520..d816deac906f 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -374,15 +374,31 @@ enum iommu_hwpt_data_type {
* @size: sizeof(struct iommu_hwpt_alloc)
* @flags: Combination of enum iommufd_hwpt_alloc_flags
* @dev_id: The device to allocate this HWPT for
- * @pt_id: The IOAS to connect this HWPT to
+ * @pt_id: The IOAS or HWPT to connect this HWPT to
* @out_hwpt_id: The ID of the new HWPT
* @__reserved: Must be 0
+ * @data_type: One of enum iommu_hwpt_data_type
+ * @data_len: Length of the type specific data
+ * @data_uptr: User pointer to the type specific data
*
* Explicitly allocate a hardware page table object. This is the same object
* type that is returned by iommufd_device_attach() and represents the
* underlying iommu driver's iommu_domain kernel object.
*
- * A HWPT will be created with the IOVA mappings from the given IOAS.
+ * A kernel-managed HWPT will be created with the mappings from the given
+ * IOAS via the @pt_id. The @data_type for this allocation must be set to
+ * IOMMU_HWPT_DATA_NONE. The HWPT can be allocated as a parent HWPT for a
+ * nesting configuration by passing IOMMU_HWPT_ALLOC_NEST_PARENT via @flags.
+ *
+ * A user-managed nested HWPT will be created from a given parent HWPT via
+ * @pt_id, in which the parent HWPT must be allocated previously via the
+ * same ioctl from a given IOAS (@pt_id). In this case, the @data_type
+ * must be set to a pre-defined type corresponding to an I/O page table
+ * type supported by the underlying IOMMU hardware.
+ *
+ * If the @data_type is set to IOMMU_HWPT_DATA_NONE, @data_len and
+ * @data_uptr should be zero. Otherwise, both @data_len and @data_uptr
+ * must be given.
*/
struct iommu_hwpt_alloc {
__u32 size;
@@ -391,6 +407,9 @@ struct iommu_hwpt_alloc {
__u32 pt_id;
__u32 out_hwpt_id;
__u32 __reserved;
+ __u32 data_type;
+ __u32 data_len;
+ __aligned_u64 data_uptr;
};
#define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)

--
2.34.1