[RFC PATCHES 12/17] iommufd: Add io page fault response support

[Lu Baolu]

Externd the IOMMUFD framework to provide a user space API for responding
to page faults.

Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/iommufd/iommufd_private.h |  1 +
 include/uapi/linux/iommufd.h            | 23 +++++++++++
 drivers/iommu/iommufd/hw_pagetable.c    | 54 +++++++++++++++++++++++++
 drivers/iommu/iommufd/main.c            |  3 ++
 4 files changed, 81 insertions(+)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 6da0ba9421d0..0985e83a611f 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -288,6 +288,7 @@ void iommufd_hw_pagetable_destroy(struct iommufd_object *obj);
 void iommufd_hw_pagetable_abort(struct iommufd_object *obj);
 int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd);
 int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd);
+int iommufd_hwpt_page_response(struct iommufd_ucmd *ucmd);
 
 static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
 					    struct iommufd_hw_pagetable *hwpt)
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 63863e21d043..65bb856dd8fb 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -50,6 +50,7 @@ enum {
 	IOMMUFD_CMD_HWPT_INVALIDATE,
 	IOMMUFD_CMD_DEVICE_SET_DATA,
 	IOMMUFD_CMD_DEVICE_UNSET_DATA,
+	IOMMUFD_CMD_PAGE_RESPONSE,
 };
 
 /**
@@ -779,4 +780,26 @@ struct iommu_device_unset_data {
 	__u32 dev_id;
 };
 #define IOMMU_DEVICE_UNSET_DATA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_UNSET_DATA)
+
+/**
+ * struct iommu_hwpt_page_response - ioctl(IOMMUFD_CMD_PAGE_RESPONSE)
+ * @size: sizeof(struct iommu_hwpt_page_response)
+ * @flags: encodes whether the corresponding fields are valid
+ *         (IOMMU_PGFAULT_FLAGS_* values)
+ * @hwpt_id: hwpt ID of target hardware page table for the response
+ * @dev_id: device ID of target device for the response
+ * @pasid: Process Address Space ID
+ * @grpid: Page Request Group Index
+ * @code: response code from &enum iommu_page_response_code
+ */
+struct iommu_hwpt_page_response {
+	__u32 size;
+	__u32 flags;
+	__u32 hwpt_id;
+	__u32 dev_id;
+	__u32 pasid;
+	__u32 grpid;
+	__u32 code;
+};
+#define IOMMU_PAGE_RESPONSE _IO(IOMMUFD_TYPE, IOMMUFD_CMD_PAGE_RESPONSE)
 #endif
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 09377a98069b..c1f3ebdce796 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -521,3 +521,57 @@ static void hw_pagetable_fault_free(struct hw_pgtable_fault *fault)
 	eventfd_ctx_put(fault->trigger);
 	kfree(fault);
 }
+
+int iommufd_hwpt_page_response(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_hwpt_page_response *cmd = ucmd->cmd;
+	struct iommu_page_response resp = {};
+	struct iommufd_fault *curr, *next;
+	struct iommufd_hw_pagetable *hwpt;
+	struct iommufd_device *idev;
+	int rc = -EINVAL;
+
+	hwpt = iommufd_get_hwpt(ucmd, cmd->hwpt_id);
+	if (IS_ERR(hwpt))
+		return rc;
+
+	if (!hwpt->parent || !hwpt->fault)
+		goto out_put_hwpt;
+
+	idev = iommufd_get_device(ucmd, cmd->dev_id);
+	if (IS_ERR(idev))
+		goto out_put_hwpt;
+
+	mutex_lock(&hwpt->fault->mutex);
+	list_for_each_entry_safe(curr, next, &hwpt->fault->response, item) {
+		if (curr->dev != idev->dev || curr->fault.grpid != cmd->grpid)
+			continue;
+
+		if ((cmd->flags & IOMMU_PGFAULT_FLAGS_PASID_VALID) &&
+		    cmd->pasid != curr->fault.pasid)
+			break;
+
+		if ((curr->fault.flags & IOMMU_PGFAULT_FLAGS_RESP_NEEDS_PASID) &&
+		    !(cmd->flags & IOMMU_PGFAULT_FLAGS_PASID_VALID))
+			break;
+
+		resp.version = IOMMU_PAGE_RESP_VERSION_1;
+		resp.pasid = cmd->pasid;
+		resp.grpid = cmd->grpid;
+		resp.code = cmd->code;
+		if (curr->fault.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)
+			resp.flags = IOMMU_PAGE_RESP_PASID_VALID;
+
+		rc = iommu_page_response(idev->dev, &resp);
+		list_del_init(&curr->item);
+		kfree(curr);
+		break;
+	}
+	mutex_unlock(&hwpt->fault->mutex);
+
+	iommufd_put_object(&idev->obj);
+out_put_hwpt:
+	iommufd_put_object(&hwpt->obj);
+
+	return rc;
+}
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index bb39dc6f3b27..0c8988808f43 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -279,6 +279,7 @@ union ucmd_buffer {
 	struct iommu_ioas_unmap unmap;
 	struct iommu_option option;
 	struct iommu_vfio_ioas vfio_ioas;
+	struct iommu_hwpt_page_response resp;
 #ifdef CONFIG_IOMMUFD_TEST
 	struct iommu_test_cmd test;
 #endif
@@ -335,6 +336,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 		 struct iommu_device_set_data, data_len),
 	IOCTL_OP(IOMMU_DEVICE_UNSET_DATA, iommufd_device_unset_data,
 		 struct iommu_device_unset_data, dev_id),
+	IOCTL_OP(IOMMU_PAGE_RESPONSE, iommufd_hwpt_page_response, struct iommu_hwpt_page_response,
+		 code),
 #ifdef CONFIG_IOMMUFD_TEST
 	IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
 #endif
-- 
2.34.1