[PATCH v6 08/10] iommufd: Associate fault object with iommufd_hw_pgtable

Lu Baolu
2024-05-27T04:08:07Z

When allocating a user iommufd_hw_pagetable, the user space is allowed to
associate a fault object with the hw_pagetable by specifying the fault
object ID in the page table allocation data and setting the
IOMMU_HWPT_FAULT_ID_VALID flag bit.

On a successful return of hwpt allocation, the user can retrieve and
respond to page faults by reading and writing the file interface of the
fault object.

Once a fault object has been associated with a hwpt, the hwpt is
iopf-capable, indicated by hwpt->fault is non NULL. Attaching,
detaching, or replacing an iopf-capable hwpt to an RID or PASID will
differ from those that are not iopf-capable.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommufd/iommufd_private.h | 9 ++++++
include/uapi/linux/iommufd.h | 8 +++++
drivers/iommu/iommufd/fault.c | 17 ++++++++++
drivers/iommu/iommufd/hw_pagetable.c | 41 +++++++++++++++++++------
4 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index ba89c86e1af7..db50881e76f6 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -457,8 +457,17 @@ struct iommufd_attach_handle {
/* Convert an iommu attach handle to iommufd handle. */
#define to_iommufd_handle(hdl) container_of(hdl, struct iommufd_attach_handle, handle)

+static inline struct iommufd_fault *
+iommufd_get_fault(struct iommufd_ucmd *ucmd, u32 id)
+{
+ return container_of(iommufd_get_object(ucmd->ictx, id,
+ IOMMUFD_OBJ_FAULT),
+ struct iommufd_fault, obj);
+}
+
int iommufd_fault_alloc(struct iommufd_ucmd *ucmd);
void iommufd_fault_destroy(struct iommufd_object *obj);
+int iommufd_fault_iopf_handler(struct iopf_group *group);

int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
struct iommufd_device *idev);
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index eba452d4344e..5391db3a7180 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -357,10 +357,13 @@ struct iommu_vfio_ioas {
* the parent HWPT in a nesting configuration.
* @IOMMU_HWPT_ALLOC_DIRTY_TRACKING: Dirty tracking support for device IOMMU is
* enforced on device attachment
+ * @IOMMU_HWPT_FAULT_ID_VALID: The fault_id field of hwpt allocation data is
+ * valid.
*/
enum iommufd_hwpt_alloc_flags {
IOMMU_HWPT_ALLOC_NEST_PARENT = 1 << 0,
IOMMU_HWPT_ALLOC_DIRTY_TRACKING = 1 << 1,
+ IOMMU_HWPT_FAULT_ID_VALID = 1 << 2,
};

/**
@@ -412,6 +415,9 @@ enum iommu_hwpt_data_type {
* @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
+ * @fault_id: The ID of IOMMUFD_FAULT object. Valid only if flags field of
+ * IOMMU_HWPT_FAULT_ID_VALID is set.
+ * @__reserved2: Padding to 64-bit alignment. Must be 0.
*
* Explicitly allocate a hardware page table object. This is the same object
* type that is returned by iommufd_device_attach() and represents the
@@ -442,6 +448,8 @@ struct iommu_hwpt_alloc {
__u32 data_type;
__u32 data_len;
__aligned_u64 data_uptr;
+ __u32 fault_id;
+ __u32 __reserved2;
};
#define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)

diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index 94dde1f57cfc..dd07e3b1b4c1 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -416,3 +416,20 @@ int iommufd_fault_alloc(struct iommufd_ucmd *ucmd)

return rc;
}
+
+int iommufd_fault_iopf_handler(struct iopf_group *group)
+{
+ struct iommufd_hw_pagetable *hwpt;
+ struct iommufd_fault *fault;
+
+ hwpt = group->attach_handle->domain->fault_data;
+ fault = hwpt->fault;
+
+ mutex_lock(&fault->mutex);
+ list_add_tail(&group->node, &fault->deliver);
+ mutex_unlock(&fault->mutex);
+
+ wake_up_interruptible(&fault->wait_queue);
+
+ return 0;
+}
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 33d142f8057d..14a32bf80549 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -8,6 +8,15 @@
#include "../iommu-priv.h"
#include "iommufd_private.h"

+static void __iommufd_hwpt_destroy(struct iommufd_hw_pagetable *hwpt)
+{
+ if (hwpt->domain)
+ iommu_domain_free(hwpt->domain);
+
+ if (hwpt->fault)
+ iommufd_put_object(hwpt->fault->ictx, &hwpt->fault->obj);
+}
+
void iommufd_hwpt_paging_destroy(struct iommufd_object *obj)
{
struct iommufd_hwpt_paging *hwpt_paging =
@@ -22,9 +31,7 @@ void iommufd_hwpt_paging_destroy(struct iommufd_object *obj)
hwpt_paging->common.domain);
}

- if (hwpt_paging->common.domain)
- iommu_domain_free(hwpt_paging->common.domain);
-
+ __iommufd_hwpt_destroy(&hwpt_paging->common);
refcount_dec(&hwpt_paging->ioas->obj.users);
}

@@ -49,9 +56,7 @@ 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);
-
+ __iommufd_hwpt_destroy(&hwpt_nested->common);
refcount_dec(&hwpt_nested->parent->common.obj.users);
}

@@ -213,7 +218,8 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
struct iommufd_hw_pagetable *hwpt;
int rc;

- if (flags || !user_data->len || !ops->domain_alloc_user)
+ if ((flags & ~IOMMU_HWPT_FAULT_ID_VALID) ||
+ !user_data->len || !ops->domain_alloc_user)
return ERR_PTR(-EOPNOTSUPP);
if (parent->auto_domain || !parent->nest_parent)
return ERR_PTR(-EINVAL);
@@ -227,7 +233,8 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
refcount_inc(&parent->common.obj.users);
hwpt_nested->parent = parent;

- hwpt->domain = ops->domain_alloc_user(idev->dev, flags,
+ hwpt->domain = ops->domain_alloc_user(idev->dev,
+ flags & ~IOMMU_HWPT_FAULT_ID_VALID,
parent->common.domain, user_data);
if (IS_ERR(hwpt->domain)) {
rc = PTR_ERR(hwpt->domain);
@@ -308,13 +315,29 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
goto out_put_pt;
}

+ if (cmd->flags & IOMMU_HWPT_FAULT_ID_VALID) {
+ struct iommufd_fault *fault;
+
+ fault = iommufd_get_fault(ucmd, cmd->fault_id);
+ if (IS_ERR(fault)) {
+ rc = PTR_ERR(fault);
+ goto out_hwpt;
+ }
+ hwpt->fault = fault;
+ hwpt->domain->iopf_handler = iommufd_fault_iopf_handler;
+ hwpt->domain->fault_data = hwpt;
+ }
+
cmd->out_hwpt_id = hwpt->obj.id;
rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
if (rc)
- goto out_hwpt;
+ goto out_put_fault;
iommufd_object_finalize(ucmd->ictx, &hwpt->obj);
goto out_unlock;

+out_put_fault:
+ if (cmd->flags & IOMMU_HWPT_FAULT_ID_VALID)
+ iommufd_put_object(ucmd->ictx, &hwpt->fault->obj);
out_hwpt:
iommufd_object_abort_and_destroy(ucmd->ictx, &hwpt->obj);
out_unlock:
--
2.34.1