Commit bf3255b3 authored by Jean-Philippe Brucker's avatar Jean-Philippe Brucker Committed by Joerg Roedel
Browse files

iommu: Add recoverable fault reporting 



Some IOMMU hardware features, for example PCI PRI and Arm SMMU Stall,
enable recoverable I/O page faults. Allow IOMMU drivers to report PRI Page
Requests and Stall events through the new fault reporting API. The
consumer of the fault can be either an I/O page fault handler in the host,
or a guest OS.

Once handled, the fault must be completed by sending a page response back
to the IOMMU. Add an iommu_page_response() function to complete a page
fault.

There are two ways to extend the userspace API:
* Add a field to iommu_page_response and a flag to
  iommu_page_response::flags describing the validity of this field.
* Introduce a new iommu_page_response_X structure with a different version
  number. The kernel must then support both versions.

Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: default avatarJean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 0c830e6b

drivers/iommu/iommu.c

+92 −2
Original line number Diff line number Diff line
@@ -891,7 +891,14 @@ EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); 
 * @data: private data passed as argument to the handler

 *

 * When an IOMMU fault event is received, this handler gets called with the

 * fault event and data as argument. The handler should return 0 on success.

 * fault event and data as argument. The handler should return 0 on success. If

 * the fault is recoverable (IOMMU_FAULT_PAGE_REQ), the consumer should also

 * complete the fault by calling iommu_page_response() with one of the following

 * response code:

 * - IOMMU_PAGE_RESP_SUCCESS: retry the translation

 * - IOMMU_PAGE_RESP_INVALID: terminate the fault

 * - IOMMU_PAGE_RESP_FAILURE: terminate the fault and stop reporting

 *   page faults if possible.

 *

 * Return 0 if the fault handler was installed successfully, or an error.

 */
@@ -921,6 +928,8 @@ int iommu_register_device_fault_handler(struct device *dev, 
	}

	param->fault_param->handler = handler;

	param->fault_param->data = data;

	mutex_init(&param->fault_param->lock);

	INIT_LIST_HEAD(&param->fault_param->faults);



done_unlock:

	mutex_unlock(&param->lock);
@@ -951,6 +960,12 @@ int iommu_unregister_device_fault_handler(struct device *dev) 
	if (!param->fault_param)

		goto unlock;



	/* we cannot unregister handler if there are pending faults */

	if (!list_empty(&param->fault_param->faults)) {

		ret = -EBUSY;

		goto unlock;

	}



	kfree(param->fault_param);

	param->fault_param = NULL;

	put_device(dev);
@@ -967,13 +982,15 @@ EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler); 
 * @evt: fault event data

 *

 * Called by IOMMU drivers when a fault is detected, typically in a threaded IRQ

 * handler.

 * handler. When this function fails and the fault is recoverable, it is the

 * caller's responsibility to complete the fault.

 *

 * Return 0 on success, or an error.

 */

int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt)

{

	struct iommu_param *param = dev->iommu_param;

	struct iommu_fault_event *evt_pending = NULL;

	struct iommu_fault_param *fparam;

	int ret = 0;
@@ -987,13 +1004,86 @@ int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt) 
		ret = -EINVAL;

		goto done_unlock;

	}



	if (evt->fault.type == IOMMU_FAULT_PAGE_REQ &&

	    (evt->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {

		evt_pending = kmemdup(evt, sizeof(struct iommu_fault_event),

				      GFP_KERNEL);

		if (!evt_pending) {

			ret = -ENOMEM;

			goto done_unlock;

		}

		mutex_lock(&fparam->lock);

		list_add_tail(&evt_pending->list, &fparam->faults);

		mutex_unlock(&fparam->lock);

	}



	ret = fparam->handler(&evt->fault, fparam->data);

	if (ret && evt_pending) {

		mutex_lock(&fparam->lock);

		list_del(&evt_pending->list);

		mutex_unlock(&fparam->lock);

		kfree(evt_pending);

	}

done_unlock:

	mutex_unlock(&param->lock);

	return ret;

}

EXPORT_SYMBOL_GPL(iommu_report_device_fault);



int iommu_page_response(struct device *dev,

			struct iommu_page_response *msg)

{

	bool pasid_valid;

	int ret = -EINVAL;

	struct iommu_fault_event *evt;

	struct iommu_fault_page_request *prm;

	struct iommu_param *param = dev->iommu_param;

	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);



	if (!domain || !domain->ops->page_response)

		return -ENODEV;



	if (!param || !param->fault_param)

		return -EINVAL;



	if (msg->version != IOMMU_PAGE_RESP_VERSION_1 ||

	    msg->flags & ~IOMMU_PAGE_RESP_PASID_VALID)

		return -EINVAL;



	/* Only send response if there is a fault report pending */

	mutex_lock(&param->fault_param->lock);

	if (list_empty(&param->fault_param->faults)) {

		dev_warn_ratelimited(dev, "no pending PRQ, drop response\n");

		goto done_unlock;

	}

	/*

	 * Check if we have a matching page request pending to respond,

	 * otherwise return -EINVAL

	 */

	list_for_each_entry(evt, &param->fault_param->faults, list) {

		prm = &evt->fault.prm;

		pasid_valid = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;



		if ((pasid_valid && prm->pasid != msg->pasid) ||

		    prm->grpid != msg->grpid)

			continue;



		/* Sanitize the reply */

		msg->flags = pasid_valid ? IOMMU_PAGE_RESP_PASID_VALID : 0;



		ret = domain->ops->page_response(dev, evt, msg);

		list_del(&evt->list);

		kfree(evt);

		break;

	}



done_unlock:

	mutex_unlock(&param->fault_param->lock);

	return ret;

}

EXPORT_SYMBOL_GPL(iommu_page_response);



/**

 * iommu_group_id - Return ID for a group

 * @group: the group to ID

include/linux/iommu.h

+19 −0
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ struct iommu_sva_ops { 
 * @sva_bind: Bind process address space to device

 * @sva_unbind: Unbind process address space from device

 * @sva_get_pasid: Get PASID associated to a SVA handle

 * @page_response: handle page request response

 * @pgsize_bitmap: bitmap of all possible supported page sizes

 */

struct iommu_ops {
@@ -287,6 +288,10 @@ struct iommu_ops { 
	void (*sva_unbind)(struct iommu_sva *handle);

	int (*sva_get_pasid)(struct iommu_sva *handle);



	int (*page_response)(struct device *dev,

			     struct iommu_fault_event *evt,

			     struct iommu_page_response *msg);



	unsigned long pgsize_bitmap;

};
@@ -311,19 +316,25 @@ struct iommu_device { 
 * unrecoverable faults such as DMA or IRQ remapping faults.

 *

 * @fault: fault descriptor

 * @list: pending fault event list, used for tracking responses

 */

struct iommu_fault_event {

	struct iommu_fault fault;

	struct list_head list;

};



/**

 * struct iommu_fault_param - per-device IOMMU fault data

 * @handler: Callback function to handle IOMMU faults at device level

 * @data: handler private data

 * @faults: holds the pending faults which needs response

 * @lock: protect pending faults list

 */

struct iommu_fault_param {

	iommu_dev_fault_handler_t handler;

	void *data;

	struct list_head faults;

	struct mutex lock;

};



/**
@@ -437,6 +448,8 @@ extern int iommu_unregister_device_fault_handler(struct device *dev); 


extern int iommu_report_device_fault(struct device *dev,

				     struct iommu_fault_event *evt);

extern int iommu_page_response(struct device *dev,

			       struct iommu_page_response *msg);



extern int iommu_group_id(struct iommu_group *group);

extern struct iommu_group *iommu_group_get_for_dev(struct device *dev);
@@ -765,6 +778,12 @@ int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt) 
	return -ENODEV;

}



static inline int iommu_page_response(struct device *dev,

				      struct iommu_page_response *msg)

{

	return -ENODEV;

}



static inline int iommu_group_id(struct iommu_group *group)

{

	return -ENODEV;

include/uapi/linux/iommu.h

+35 −0
Original line number Diff line number Diff line
@@ -115,4 +115,39 @@ struct iommu_fault { 
		struct iommu_fault_page_request prm;

	};

};



/**

 * enum iommu_page_response_code - Return status of fault handlers

 * @IOMMU_PAGE_RESP_SUCCESS: Fault has been handled and the page tables

 *	populated, retry the access. This is "Success" in PCI PRI.

 * @IOMMU_PAGE_RESP_FAILURE: General error. Drop all subsequent faults from

 *	this device if possible. This is "Response Failure" in PCI PRI.

 * @IOMMU_PAGE_RESP_INVALID: Could not handle this fault, don't retry the

 *	access. This is "Invalid Request" in PCI PRI.

 */

enum iommu_page_response_code {

	IOMMU_PAGE_RESP_SUCCESS = 0,

	IOMMU_PAGE_RESP_INVALID,

	IOMMU_PAGE_RESP_FAILURE,

};



/**

 * struct iommu_page_response - Generic page response information

 * @version: API version of this structure

 * @flags: encodes whether the corresponding fields are valid

 *         (IOMMU_FAULT_PAGE_RESPONSE_* values)

 * @pasid: Process Address Space ID

 * @grpid: Page Request Group Index

 * @code: response code from &enum iommu_page_response_code

 */

struct iommu_page_response {

#define IOMMU_PAGE_RESP_VERSION_1	1

	__u32	version;

#define IOMMU_PAGE_RESP_PASID_VALID	(1 << 0)

	__u32	flags;

	__u32	pasid;

	__u32	grpid;

	__u32	code;

};



#endif /* _UAPI_IOMMU_H */

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