drivers/gpu/drm/amd/amdkfd/kfd_iommu.c - linux - Git at Google

 /*
  * Copyright 2018 Advanced Micro Devices, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */

 #include <linux/printk.h>
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/pci.h>
 #include <linux/amd-iommu.h>
 #include "kfd_priv.h"
 #include "kfd_dbgmgr.h"
 #include "kfd_topology.h"
 #include "kfd_iommu.h"

 static const u32 required_iommu_flags = AMD_IOMMU_DEVICE_FLAG_ATS_SUP |
 					AMD_IOMMU_DEVICE_FLAG_PRI_SUP |
 					AMD_IOMMU_DEVICE_FLAG_PASID_SUP;

 /** kfd_iommu_check_device - Check whether IOMMU is available for device
  */
 int kfd_iommu_check_device(struct kfd_dev *kfd)
 {
 	struct amd_iommu_device_info iommu_info;
 	int err;

 	if (!kfd->use_iommu_v2)
 		return -ENODEV;

 	iommu_info.flags = 0;
 	err = amd_iommu_device_info(kfd->pdev, &iommu_info);
 	if (err)
 		return err;

 	if ((iommu_info.flags & required_iommu_flags) != required_iommu_flags)
 		return -ENODEV;

 	return 0;
 }

 /** kfd_iommu_device_init - Initialize IOMMU for device
  */
 int kfd_iommu_device_init(struct kfd_dev *kfd)
 {
 	struct amd_iommu_device_info iommu_info;
 	unsigned int pasid_limit;
 	int err;

 	if (!kfd->use_iommu_v2)
 		return 0;

 	iommu_info.flags = 0;
 	err = amd_iommu_device_info(kfd->pdev, &iommu_info);
 	if (err < 0) {
 		dev_err(kfd_device,
 			"error getting iommu info. is the iommu enabled?\n");
 		return -ENODEV;
 	}

 	if ((iommu_info.flags & required_iommu_flags) != required_iommu_flags) {
 		dev_err(kfd_device,
 			"error required iommu flags ats %i, pri %i, pasid %i\n",
 		       (iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_ATS_SUP) != 0,
 		       (iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_PRI_SUP) != 0,
 		       (iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_PASID_SUP)
 									!= 0);
 		return -ENODEV;
 	}

 	pasid_limit = min_t(unsigned int,
 			(unsigned int)(1 << kfd->device_info->max_pasid_bits),
 			iommu_info.max_pasids);

 	if (!kfd_set_pasid_limit(pasid_limit)) {
 		dev_err(kfd_device, "error setting pasid limit\n");
 		return -EBUSY;
 	}

 	return 0;
 }

 /** kfd_iommu_bind_process_to_device - Have the IOMMU bind a process
  *
  * Binds the given process to the given device using its PASID. This
  * enables IOMMUv2 address translation for the process on the device.
  *
  * This function assumes that the process mutex is held.
  */
 int kfd_iommu_bind_process_to_device(struct kfd_process_device *pdd)
 {
 	struct kfd_dev *dev = pdd->dev;
 	struct kfd_process *p = pdd->process;
 	int err;

 	if (!dev->use_iommu_v2 || pdd->bound == PDD_BOUND)
 		return 0;

 	if (unlikely(pdd->bound == PDD_BOUND_SUSPENDED)) {
 		pr_err("Binding PDD_BOUND_SUSPENDED pdd is unexpected!\n");
 		return -EINVAL;
 	}

 	err = amd_iommu_bind_pasid(dev->pdev, p->pasid, p->lead_thread);
 	if (!err)
 		pdd->bound = PDD_BOUND;

 	return err;
 }

 /** kfd_iommu_unbind_process - Unbind process from all devices
  *
  * This removes all IOMMU device bindings of the process. To be used
  * before process termination.
  */
 void kfd_iommu_unbind_process(struct kfd_process *p)
 {
 	struct kfd_process_device *pdd;

 	list_for_each_entry(pdd, &p->per_device_data, per_device_list)
 		if (pdd->bound == PDD_BOUND)
 			amd_iommu_unbind_pasid(pdd->dev->pdev, p->pasid);
 }

 /* Callback for process shutdown invoked by the IOMMU driver */
 static void iommu_pasid_shutdown_callback(struct pci_dev *pdev, u32 pasid)
 {
 	struct kfd_dev *dev = kfd_device_by_pci_dev(pdev);
 	struct kfd_process *p;
 	struct kfd_process_device *pdd;

 	if (!dev)
 		return;

 	/*
 	 * Look for the process that matches the pasid. If there is no such
 	 * process, we either released it in amdkfd's own notifier, or there
 	 * is a bug. Unfortunately, there is no way to tell...
 	 */
 	p = kfd_lookup_process_by_pasid(pasid);
 	if (!p)
 		return;

 	pr_debug("Unbinding process 0x%x from IOMMU\n", pasid);

 	mutex_lock(kfd_get_dbgmgr_mutex());

 	if (dev->dbgmgr && dev->dbgmgr->pasid == p->pasid) {
 		if (!kfd_dbgmgr_unregister(dev->dbgmgr, p)) {
 			kfd_dbgmgr_destroy(dev->dbgmgr);
 			dev->dbgmgr = NULL;
 		}
 	}

 	mutex_unlock(kfd_get_dbgmgr_mutex());

 	mutex_lock(&p->mutex);

 	pdd = kfd_get_process_device_data(dev, p);
 	if (pdd)
 		/* For GPU relying on IOMMU, we need to dequeue here
 		 * when PASID is still bound.
 		 */
 		kfd_process_dequeue_from_device(pdd);

 	mutex_unlock(&p->mutex);

 	kfd_unref_process(p);
 }

 /* This function called by IOMMU driver on PPR failure */
 static int iommu_invalid_ppr_cb(struct pci_dev *pdev, u32 pasid,
 				unsigned long address, u16 flags)
 {
 	struct kfd_dev *dev;

 	dev_warn_ratelimited(kfd_device,
 			"Invalid PPR device %x:%x.%x pasid 0x%x address 0x%lX flags 0x%X",
 			pdev->bus->number,
 			PCI_SLOT(pdev->devfn),
 			PCI_FUNC(pdev->devfn),
 			pasid,
 			address,
 			flags);

 	dev = kfd_device_by_pci_dev(pdev);
 	if (!WARN_ON(!dev))
 		kfd_signal_iommu_event(dev, pasid, address,
 			flags & PPR_FAULT_WRITE, flags & PPR_FAULT_EXEC);

 	return AMD_IOMMU_INV_PRI_RSP_INVALID;
 }

 /*
  * Bind processes do the device that have been temporarily unbound
  * (PDD_BOUND_SUSPENDED) in kfd_unbind_processes_from_device.
  */
 static int kfd_bind_processes_to_device(struct kfd_dev *kfd)
 {
 	struct kfd_process_device *pdd;
 	struct kfd_process *p;
 	unsigned int temp;
 	int err = 0;

 	int idx = srcu_read_lock(&kfd_processes_srcu);

 	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
 		mutex_lock(&p->mutex);
 		pdd = kfd_get_process_device_data(kfd, p);

 		if (WARN_ON(!pdd) || pdd->bound != PDD_BOUND_SUSPENDED) {
 			mutex_unlock(&p->mutex);
 			continue;
 		}

 		err = amd_iommu_bind_pasid(kfd->pdev, p->pasid,
 				p->lead_thread);
 		if (err < 0) {
 			pr_err("Unexpected pasid 0x%x binding failure\n",
 					p->pasid);
 			mutex_unlock(&p->mutex);
 			break;
 		}

 		pdd->bound = PDD_BOUND;
 		mutex_unlock(&p->mutex);
 	}

 	srcu_read_unlock(&kfd_processes_srcu, idx);

 	return err;
 }

 /*
  * Mark currently bound processes as PDD_BOUND_SUSPENDED. These
  * processes will be restored to PDD_BOUND state in
  * kfd_bind_processes_to_device.
  */
 static void kfd_unbind_processes_from_device(struct kfd_dev *kfd)
 {
 	struct kfd_process_device *pdd;
 	struct kfd_process *p;
 	unsigned int temp;

 	int idx = srcu_read_lock(&kfd_processes_srcu);

 	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
 		mutex_lock(&p->mutex);
 		pdd = kfd_get_process_device_data(kfd, p);

 		if (WARN_ON(!pdd)) {
 			mutex_unlock(&p->mutex);
 			continue;
 		}

 		if (pdd->bound == PDD_BOUND)
 			pdd->bound = PDD_BOUND_SUSPENDED;
 		mutex_unlock(&p->mutex);
 	}

 	srcu_read_unlock(&kfd_processes_srcu, idx);
 }

 /** kfd_iommu_suspend - Prepare IOMMU for suspend
  *
  * This unbinds processes from the device and disables the IOMMU for
  * the device.
  */
 void kfd_iommu_suspend(struct kfd_dev *kfd)
 {
 	if (!kfd->use_iommu_v2)
 		return;

 	kfd_unbind_processes_from_device(kfd);

 	amd_iommu_set_invalidate_ctx_cb(kfd->pdev, NULL);
 	amd_iommu_set_invalid_ppr_cb(kfd->pdev, NULL);
 	amd_iommu_free_device(kfd->pdev);
 }

 /** kfd_iommu_resume - Restore IOMMU after resume
  *
  * This reinitializes the IOMMU for the device and re-binds previously
  * suspended processes to the device.
  */
 int kfd_iommu_resume(struct kfd_dev *kfd)
 {
 	unsigned int pasid_limit;
 	int err;

 	if (!kfd->use_iommu_v2)
 		return 0;

 	pasid_limit = kfd_get_pasid_limit();

 	err = amd_iommu_init_device(kfd->pdev, pasid_limit);
 	if (err)
 		return -ENXIO;

 	amd_iommu_set_invalidate_ctx_cb(kfd->pdev,
 					iommu_pasid_shutdown_callback);
 	amd_iommu_set_invalid_ppr_cb(kfd->pdev,
 				     iommu_invalid_ppr_cb);

 	err = kfd_bind_processes_to_device(kfd);
 	if (err) {
 		amd_iommu_set_invalidate_ctx_cb(kfd->pdev, NULL);
 		amd_iommu_set_invalid_ppr_cb(kfd->pdev, NULL);
 		amd_iommu_free_device(kfd->pdev);
 		return err;
 	}

 	return 0;
 }

 extern bool amd_iommu_pc_supported(void);
 extern u8 amd_iommu_pc_get_max_banks(u16 devid);
 extern u8 amd_iommu_pc_get_max_counters(u16 devid);

 /** kfd_iommu_add_perf_counters - Add IOMMU performance counters to topology
  */
 int kfd_iommu_add_perf_counters(struct kfd_topology_device *kdev)
 {
 	struct kfd_perf_properties *props;

 	if (!(kdev->node_props.capability & HSA_CAP_ATS_PRESENT))
 		return 0;

 	if (!amd_iommu_pc_supported())
 		return 0;

 	props = kfd_alloc_struct(props);
 	if (!props)
 		return -ENOMEM;
 	strcpy(props->block_name, "iommu");
 	props->max_concurrent = amd_iommu_pc_get_max_banks(0) *
 		amd_iommu_pc_get_max_counters(0); /* assume one iommu */
 	list_add_tail(&props->list, &kdev->perf_props);

 	return 0;
 }
	/*
	* Copyright 2018 Advanced Micro Devices, Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*/

	#include <linux/printk.h>
	#include <linux/device.h>
	#include <linux/slab.h>
	#include <linux/pci.h>
	#include <linux/amd-iommu.h>
	#include "kfd_priv.h"
	#include "kfd_dbgmgr.h"
	#include "kfd_topology.h"
	#include "kfd_iommu.h"

	static const u32 required_iommu_flags = AMD_IOMMU_DEVICE_FLAG_ATS_SUP \|
	AMD_IOMMU_DEVICE_FLAG_PRI_SUP \|
	AMD_IOMMU_DEVICE_FLAG_PASID_SUP;

	/** kfd_iommu_check_device - Check whether IOMMU is available for device
	*/
	int kfd_iommu_check_device(struct kfd_dev *kfd)
	{
	struct amd_iommu_device_info iommu_info;
	int err;

	if (!kfd->use_iommu_v2)
	return -ENODEV;

	iommu_info.flags = 0;
	err = amd_iommu_device_info(kfd->pdev, &iommu_info);
	if (err)
	return err;

	if ((iommu_info.flags & required_iommu_flags) != required_iommu_flags)
	return -ENODEV;

	return 0;
	}

	/** kfd_iommu_device_init - Initialize IOMMU for device
	*/
	int kfd_iommu_device_init(struct kfd_dev *kfd)
	{
	struct amd_iommu_device_info iommu_info;
	unsigned int pasid_limit;
	int err;

	if (!kfd->use_iommu_v2)
	return 0;

	iommu_info.flags = 0;
	err = amd_iommu_device_info(kfd->pdev, &iommu_info);
	if (err < 0) {
	dev_err(kfd_device,
	"error getting iommu info. is the iommu enabled?\n");
	return -ENODEV;
	}

	if ((iommu_info.flags & required_iommu_flags) != required_iommu_flags) {
	dev_err(kfd_device,
	"error required iommu flags ats %i, pri %i, pasid %i\n",
	(iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_ATS_SUP) != 0,
	(iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_PRI_SUP) != 0,
	(iommu_info.flags & AMD_IOMMU_DEVICE_FLAG_PASID_SUP)
	!= 0);
	return -ENODEV;
	}

	pasid_limit = min_t(unsigned int,
	(unsigned int)(1 << kfd->device_info->max_pasid_bits),
	iommu_info.max_pasids);

	if (!kfd_set_pasid_limit(pasid_limit)) {
	dev_err(kfd_device, "error setting pasid limit\n");
	return -EBUSY;
	}

	return 0;
	}

	/** kfd_iommu_bind_process_to_device - Have the IOMMU bind a process
	*
	* Binds the given process to the given device using its PASID. This
	* enables IOMMUv2 address translation for the process on the device.
	*
	* This function assumes that the process mutex is held.
	*/
	int kfd_iommu_bind_process_to_device(struct kfd_process_device *pdd)
	{
	struct kfd_dev *dev = pdd->dev;
	struct kfd_process *p = pdd->process;
	int err;

	if (!dev->use_iommu_v2 \|\| pdd->bound == PDD_BOUND)
	return 0;

	if (unlikely(pdd->bound == PDD_BOUND_SUSPENDED)) {
	pr_err("Binding PDD_BOUND_SUSPENDED pdd is unexpected!\n");
	return -EINVAL;
	}

	err = amd_iommu_bind_pasid(dev->pdev, p->pasid, p->lead_thread);
	if (!err)
	pdd->bound = PDD_BOUND;

	return err;
	}

	/** kfd_iommu_unbind_process - Unbind process from all devices
	*
	* This removes all IOMMU device bindings of the process. To be used
	* before process termination.
	*/
	void kfd_iommu_unbind_process(struct kfd_process *p)
	{
	struct kfd_process_device *pdd;

	list_for_each_entry(pdd, &p->per_device_data, per_device_list)
	if (pdd->bound == PDD_BOUND)
	amd_iommu_unbind_pasid(pdd->dev->pdev, p->pasid);
	}

	/* Callback for process shutdown invoked by the IOMMU driver */
	static void iommu_pasid_shutdown_callback(struct pci_dev *pdev, u32 pasid)
	{
	struct kfd_dev *dev = kfd_device_by_pci_dev(pdev);
	struct kfd_process *p;
	struct kfd_process_device *pdd;

	if (!dev)
	return;

	/*
	* Look for the process that matches the pasid. If there is no such
	* process, we either released it in amdkfd's own notifier, or there
	* is a bug. Unfortunately, there is no way to tell...
	*/
	p = kfd_lookup_process_by_pasid(pasid);
	if (!p)
	return;

	pr_debug("Unbinding process 0x%x from IOMMU\n", pasid);

	mutex_lock(kfd_get_dbgmgr_mutex());

	if (dev->dbgmgr && dev->dbgmgr->pasid == p->pasid) {
	if (!kfd_dbgmgr_unregister(dev->dbgmgr, p)) {
	kfd_dbgmgr_destroy(dev->dbgmgr);
	dev->dbgmgr = NULL;
	}
	}

	mutex_unlock(kfd_get_dbgmgr_mutex());

	mutex_lock(&p->mutex);

	pdd = kfd_get_process_device_data(dev, p);
	if (pdd)
	/* For GPU relying on IOMMU, we need to dequeue here
	* when PASID is still bound.
	*/
	kfd_process_dequeue_from_device(pdd);

	mutex_unlock(&p->mutex);

	kfd_unref_process(p);
	}

	/* This function called by IOMMU driver on PPR failure */
	static int iommu_invalid_ppr_cb(struct pci_dev *pdev, u32 pasid,
	unsigned long address, u16 flags)
	{
	struct kfd_dev *dev;

	dev_warn_ratelimited(kfd_device,
	"Invalid PPR device %x:%x.%x pasid 0x%x address 0x%lX flags 0x%X",
	pdev->bus->number,
	PCI_SLOT(pdev->devfn),
	PCI_FUNC(pdev->devfn),
	pasid,
	address,
	flags);

	dev = kfd_device_by_pci_dev(pdev);
	if (!WARN_ON(!dev))
	kfd_signal_iommu_event(dev, pasid, address,
	flags & PPR_FAULT_WRITE, flags & PPR_FAULT_EXEC);

	return AMD_IOMMU_INV_PRI_RSP_INVALID;
	}

	/*
	* Bind processes do the device that have been temporarily unbound
	* (PDD_BOUND_SUSPENDED) in kfd_unbind_processes_from_device.
	*/
	static int kfd_bind_processes_to_device(struct kfd_dev *kfd)
	{
	struct kfd_process_device *pdd;
	struct kfd_process *p;
	unsigned int temp;
	int err = 0;

	int idx = srcu_read_lock(&kfd_processes_srcu);

	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
	mutex_lock(&p->mutex);
	pdd = kfd_get_process_device_data(kfd, p);

	if (WARN_ON(!pdd) \|\| pdd->bound != PDD_BOUND_SUSPENDED) {
	mutex_unlock(&p->mutex);
	continue;
	}

	err = amd_iommu_bind_pasid(kfd->pdev, p->pasid,
	p->lead_thread);
	if (err < 0) {
	pr_err("Unexpected pasid 0x%x binding failure\n",
	p->pasid);
	mutex_unlock(&p->mutex);
	break;
	}

	pdd->bound = PDD_BOUND;
	mutex_unlock(&p->mutex);
	}

	srcu_read_unlock(&kfd_processes_srcu, idx);

	return err;
	}

	/*
	* Mark currently bound processes as PDD_BOUND_SUSPENDED. These
	* processes will be restored to PDD_BOUND state in
	* kfd_bind_processes_to_device.
	*/
	static void kfd_unbind_processes_from_device(struct kfd_dev *kfd)
	{
	struct kfd_process_device *pdd;
	struct kfd_process *p;
	unsigned int temp;

	int idx = srcu_read_lock(&kfd_processes_srcu);

	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
	mutex_lock(&p->mutex);
	pdd = kfd_get_process_device_data(kfd, p);

	if (WARN_ON(!pdd)) {
	mutex_unlock(&p->mutex);
	continue;
	}

	if (pdd->bound == PDD_BOUND)
	pdd->bound = PDD_BOUND_SUSPENDED;
	mutex_unlock(&p->mutex);
	}

	srcu_read_unlock(&kfd_processes_srcu, idx);
	}

	/** kfd_iommu_suspend - Prepare IOMMU for suspend
	*
	* This unbinds processes from the device and disables the IOMMU for
	* the device.
	*/
	void kfd_iommu_suspend(struct kfd_dev *kfd)
	{
	if (!kfd->use_iommu_v2)
	return;

	kfd_unbind_processes_from_device(kfd);

	amd_iommu_set_invalidate_ctx_cb(kfd->pdev, NULL);
	amd_iommu_set_invalid_ppr_cb(kfd->pdev, NULL);
	amd_iommu_free_device(kfd->pdev);
	}

	/** kfd_iommu_resume - Restore IOMMU after resume
	*
	* This reinitializes the IOMMU for the device and re-binds previously
	* suspended processes to the device.
	*/
	int kfd_iommu_resume(struct kfd_dev *kfd)
	{
	unsigned int pasid_limit;
	int err;

	if (!kfd->use_iommu_v2)
	return 0;

	pasid_limit = kfd_get_pasid_limit();

	err = amd_iommu_init_device(kfd->pdev, pasid_limit);
	if (err)
	return -ENXIO;

	amd_iommu_set_invalidate_ctx_cb(kfd->pdev,
	iommu_pasid_shutdown_callback);
	amd_iommu_set_invalid_ppr_cb(kfd->pdev,
	iommu_invalid_ppr_cb);

	err = kfd_bind_processes_to_device(kfd);
	if (err) {
	amd_iommu_set_invalidate_ctx_cb(kfd->pdev, NULL);
	amd_iommu_set_invalid_ppr_cb(kfd->pdev, NULL);
	amd_iommu_free_device(kfd->pdev);
	return err;
	}

	return 0;
	}

	extern bool amd_iommu_pc_supported(void);
	extern u8 amd_iommu_pc_get_max_banks(u16 devid);
	extern u8 amd_iommu_pc_get_max_counters(u16 devid);

	/** kfd_iommu_add_perf_counters - Add IOMMU performance counters to topology
	*/
	int kfd_iommu_add_perf_counters(struct kfd_topology_device *kdev)
	{
	struct kfd_perf_properties *props;

	if (!(kdev->node_props.capability & HSA_CAP_ATS_PRESENT))
	return 0;

	if (!amd_iommu_pc_supported())
	return 0;

	props = kfd_alloc_struct(props);
	if (!props)
	return -ENOMEM;
	strcpy(props->block_name, "iommu");
	props->max_concurrent = amd_iommu_pc_get_max_banks(0) *
	amd_iommu_pc_get_max_counters(0); /* assume one iommu */
	list_add_tail(&props->list, &kdev->perf_props);

	return 0;
	}