[PATCH v5 6/9] iommufd: Fault-capable hwpt attach/detach/replace

[Lu Baolu]

Add iopf-capable hw page table attach/detach/replace helpers. The pointer
to iommufd_device is stored in the domain attachment handle, so that it
can be echo'ed back in the iopf_group.

The iopf-capable hw page tables can only be attached to devices that
support the IOMMU_DEV_FEAT_IOPF feature. On the first attachment of an
iopf-capable hw_pagetable to the device, the IOPF feature is enabled on
the device. Similarly, after the last iopf-capable hwpt is detached from
the device, the IOPF feature is disabled on the device.

The current implementation allows a replacement between iopf-capable and
non-iopf-capable hw page tables. This matches the nested translation use
case, where a parent domain is attached by default and can then be
replaced with a nested user domain with iopf support.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/iommufd/iommufd_private.h |  10 ++
 drivers/iommu/iommufd/device.c          |  15 ++-
 drivers/iommu/iommufd/fault.c           | 118 ++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index acb89bbf9f8e..18c8d7d38dcd 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -293,6 +293,7 @@ int iommufd_check_iova_range(struct io_pagetable *iopt,
 struct iommufd_hw_pagetable {
 	struct iommufd_object obj;
 	struct iommu_domain *domain;
+	struct iommufd_fault *fault;
 };
 
 struct iommufd_hwpt_paging {
@@ -396,6 +397,7 @@ struct iommufd_device {
 	/* always the physical device */
 	struct device *dev;
 	bool enforce_cache_coherency;
+	bool iopf_enabled;
 	/* outstanding faults awaiting response indexed by fault group id */
 	struct xarray faults;
 };
@@ -450,6 +452,14 @@ struct iommufd_fault {
 int iommufd_fault_alloc(struct iommufd_ucmd *ucmd);
 void iommufd_fault_destroy(struct iommufd_object *obj);
 
+int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
+				    struct iommufd_device *idev);
+void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
+				     struct iommufd_device *idev);
+int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
+				     struct iommufd_hw_pagetable *hwpt,
+				     struct iommufd_hw_pagetable *old);
+
 #ifdef CONFIG_IOMMUFD_TEST
 int iommufd_test(struct iommufd_ucmd *ucmd);
 void iommufd_selftest_destroy(struct iommufd_object *obj);
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 22e22969363a..2bee3f399ec7 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -377,7 +377,10 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 	 * attachment.
 	 */
 	if (list_empty(&idev->igroup->device_list)) {
-		rc = iommu_attach_group(hwpt->domain, idev->igroup->group);
+		if (hwpt->fault)
+			rc = iommufd_fault_domain_attach_dev(hwpt, idev);
+		else
+			rc = iommu_attach_group(hwpt->domain, idev->igroup->group);
 		if (rc)
 			goto err_unresv;
 		idev->igroup->hwpt = hwpt;
@@ -403,7 +406,10 @@ iommufd_hw_pagetable_detach(struct iommufd_device *idev)
 	mutex_lock(&idev->igroup->lock);
 	list_del(&idev->group_item);
 	if (list_empty(&idev->igroup->device_list)) {
-		iommu_detach_group(hwpt->domain, idev->igroup->group);
+		if (hwpt->fault)
+			iommufd_fault_domain_detach_dev(hwpt, idev);
+		else
+			iommu_detach_group(hwpt->domain, idev->igroup->group);
 		idev->igroup->hwpt = NULL;
 	}
 	if (hwpt_is_paging(hwpt))
@@ -498,7 +504,10 @@ iommufd_device_do_replace(struct iommufd_device *idev,
 			goto err_unlock;
 	}
 
-	rc = iommu_group_replace_domain(igroup->group, hwpt->domain);
+	if (old_hwpt->fault || hwpt->fault)
+		rc = iommufd_fault_domain_replace_dev(idev, hwpt, old_hwpt);
+	else
+		rc = iommu_group_replace_domain(igroup->group, hwpt->domain);
 	if (rc)
 		goto err_unresv;
 
diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index 13125c0feecb..6357229bf3b4 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -15,6 +15,124 @@
 #include "../iommu-priv.h"
 #include "iommufd_private.h"
 
+static int iommufd_fault_iopf_enable(struct iommufd_device *idev)
+{
+	int ret;
+
+	if (idev->iopf_enabled)
+		return 0;
+
+	ret = iommu_dev_enable_feature(idev->dev, IOMMU_DEV_FEAT_IOPF);
+	if (ret)
+		return ret;
+
+	idev->iopf_enabled = true;
+
+	return 0;
+}
+
+static void iommufd_fault_iopf_disable(struct iommufd_device *idev)
+{
+	if (!idev->iopf_enabled)
+		return;
+
+	iommu_dev_disable_feature(idev->dev, IOMMU_DEV_FEAT_IOPF);
+	idev->iopf_enabled = false;
+}
+
+int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
+				    struct iommufd_device *idev)
+{
+	struct iommu_attach_handle *handle;
+	int ret;
+
+	if (!hwpt->fault)
+		return -EINVAL;
+
+	ret = iommufd_fault_iopf_enable(idev);
+	if (ret)
+		return ret;
+
+	ret = iommu_attach_group(hwpt->domain, idev->igroup->group);
+	if (ret) {
+		iommufd_fault_iopf_disable(idev);
+		return ret;
+	}
+
+	handle = iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
+	handle->idev = idev;
+
+	return 0;
+}
+
+static void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
+					 struct iommufd_device *idev)
+{
+	struct iommufd_fault *fault = hwpt->fault;
+	struct iopf_group *group, *next;
+	unsigned long index;
+
+	if (!fault)
+		return;
+
+	mutex_lock(&fault->mutex);
+	list_for_each_entry_safe(group, next, &fault->deliver, node) {
+		if (group->domain != hwpt->domain ||
+		    group->fault_param->dev != idev->dev)
+			continue;
+		list_del(&group->node);
+		iopf_group_response(group, IOMMU_PAGE_RESP_INVALID);
+		iopf_free_group(group);
+	}
+
+	xa_for_each(&idev->faults, index, group) {
+		if (group->domain != hwpt->domain)
+			continue;
+		xa_erase(&idev->faults, index);
+		iopf_group_response(group, IOMMU_PAGE_RESP_INVALID);
+		iopf_free_group(group);
+	}
+	mutex_unlock(&fault->mutex);
+}
+
+void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
+				     struct iommufd_device *idev)
+{
+	iommu_detach_group(hwpt->domain, idev->igroup->group);
+	iommufd_fault_iopf_disable(idev);
+	iommufd_auto_response_faults(hwpt, idev);
+}
+
+int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
+				     struct iommufd_hw_pagetable *hwpt,
+				     struct iommufd_hw_pagetable *old)
+{
+	struct iommu_attach_handle *handle;
+	int ret;
+
+	if (hwpt->fault)
+		ret = iommufd_fault_iopf_enable(idev);
+	else
+		iommufd_fault_iopf_disable(idev);
+
+	ret = iommu_group_replace_domain(idev->igroup->group, hwpt->domain);
+	if (ret)
+		goto out_cleanup;
+
+	iommufd_auto_response_faults(old, idev);
+	handle = iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
+	handle->idev = idev;
+
+	return 0;
+out_cleanup:
+	if (old->fault)
+		ret = iommufd_fault_iopf_enable(idev);
+	else
+		iommufd_fault_iopf_disable(idev);
+
+	return ret;
+}
+
 void iommufd_fault_destroy(struct iommufd_object *obj)
 {
 	struct iommufd_fault *fault = container_of(obj, struct iommufd_fault, obj);
-- 
2.34.1