diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/iommu/io-pgfault.c | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c new file mode 100644 index 000000000..16e564cb3 --- /dev/null +++ b/drivers/iommu/io-pgfault.c @@ -0,0 +1,461 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Handle device page faults + * + * Copyright (C) 2020 ARM Ltd. + */ + +#include <linux/iommu.h> +#include <linux/list.h> +#include <linux/sched/mm.h> +#include <linux/slab.h> +#include <linux/workqueue.h> + +#include "iommu-sva-lib.h" + +/** + * struct iopf_queue - IO Page Fault queue + * @wq: the fault workqueue + * @devices: devices attached to this queue + * @lock: protects the device list + */ +struct iopf_queue { + struct workqueue_struct *wq; + struct list_head devices; + struct mutex lock; +}; + +/** + * struct iopf_device_param - IO Page Fault data attached to a device + * @dev: the device that owns this param + * @queue: IOPF queue + * @queue_list: index into queue->devices + * @partial: faults that are part of a Page Request Group for which the last + * request hasn't been submitted yet. + */ +struct iopf_device_param { + struct device *dev; + struct iopf_queue *queue; + struct list_head queue_list; + struct list_head partial; +}; + +struct iopf_fault { + struct iommu_fault fault; + struct list_head list; +}; + +struct iopf_group { + struct iopf_fault last_fault; + struct list_head faults; + struct work_struct work; + struct device *dev; +}; + +static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf, + enum iommu_page_response_code status) +{ + struct iommu_page_response resp = { + .version = IOMMU_PAGE_RESP_VERSION_1, + .pasid = iopf->fault.prm.pasid, + .grpid = iopf->fault.prm.grpid, + .code = status, + }; + + if ((iopf->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) && + (iopf->fault.prm.flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID)) + resp.flags = IOMMU_PAGE_RESP_PASID_VALID; + + return iommu_page_response(dev, &resp); +} + +static enum iommu_page_response_code +iopf_handle_single(struct iopf_fault *iopf) +{ + vm_fault_t ret; + struct mm_struct *mm; + struct vm_area_struct *vma; + unsigned int access_flags = 0; + unsigned int fault_flags = FAULT_FLAG_REMOTE; + struct iommu_fault_page_request *prm = &iopf->fault.prm; + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; + + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)) + return status; + + mm = iommu_sva_find(prm->pasid); + if (IS_ERR_OR_NULL(mm)) + return status; + + mmap_read_lock(mm); + + vma = vma_lookup(mm, prm->addr); + if (!vma) + /* Unmapped area */ + goto out_put_mm; + + if (prm->perm & IOMMU_FAULT_PERM_READ) + access_flags |= VM_READ; + + if (prm->perm & IOMMU_FAULT_PERM_WRITE) { + access_flags |= VM_WRITE; + fault_flags |= FAULT_FLAG_WRITE; + } + + if (prm->perm & IOMMU_FAULT_PERM_EXEC) { + access_flags |= VM_EXEC; + fault_flags |= FAULT_FLAG_INSTRUCTION; + } + + if (!(prm->perm & IOMMU_FAULT_PERM_PRIV)) + fault_flags |= FAULT_FLAG_USER; + + if (access_flags & ~vma->vm_flags) + /* Access fault */ + goto out_put_mm; + + ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL); + status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID : + IOMMU_PAGE_RESP_SUCCESS; + +out_put_mm: + mmap_read_unlock(mm); + mmput(mm); + + return status; +} + +static void iopf_handle_group(struct work_struct *work) +{ + struct iopf_group *group; + struct iopf_fault *iopf, *next; + enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS; + + group = container_of(work, struct iopf_group, work); + + list_for_each_entry_safe(iopf, next, &group->faults, list) { + /* + * For the moment, errors are sticky: don't handle subsequent + * faults in the group if there is an error. + */ + if (status == IOMMU_PAGE_RESP_SUCCESS) + status = iopf_handle_single(iopf); + + if (!(iopf->fault.prm.flags & + IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) + kfree(iopf); + } + + iopf_complete_group(group->dev, &group->last_fault, status); + kfree(group); +} + +/** + * iommu_queue_iopf - IO Page Fault handler + * @fault: fault event + * @cookie: struct device, passed to iommu_register_device_fault_handler. + * + * Add a fault to the device workqueue, to be handled by mm. + * + * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard + * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't + * expect a response. It may be generated when disabling a PASID (issuing a + * PASID stop request) by some PCI devices. + * + * The PASID stop request is issued by the device driver before unbind(). Once + * it completes, no page request is generated for this PASID anymore and + * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 - 6.20.1 + * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices will wait + * for all outstanding page requests to come back with a response before + * completing the PASID stop request. Others do not wait for page responses, and + * instead issue this Stop Marker that tells us when the PASID can be + * reallocated. + * + * It is safe to discard the Stop Marker because it is an optimization. + * a. Page requests, which are posted requests, have been flushed to the IOMMU + * when the stop request completes. + * b. The IOMMU driver flushes all fault queues on unbind() before freeing the + * PASID. + * + * So even though the Stop Marker might be issued by the device *after* the stop + * request completes, outstanding faults will have been dealt with by the time + * the PASID is freed. + * + * Return: 0 on success and <0 on error. + */ +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie) +{ + int ret; + struct iopf_group *group; + struct iopf_fault *iopf, *next; + struct iopf_device_param *iopf_param; + + struct device *dev = cookie; + struct dev_iommu *param = dev->iommu; + + lockdep_assert_held(¶m->lock); + + if (fault->type != IOMMU_FAULT_PAGE_REQ) + /* Not a recoverable page fault */ + return -EOPNOTSUPP; + + /* + * As long as we're holding param->lock, the queue can't be unlinked + * from the device and therefore cannot disappear. + */ + iopf_param = param->iopf_param; + if (!iopf_param) + return -ENODEV; + + if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) { + iopf = kzalloc(sizeof(*iopf), GFP_KERNEL); + if (!iopf) + return -ENOMEM; + + iopf->fault = *fault; + + /* Non-last request of a group. Postpone until the last one */ + list_add(&iopf->list, &iopf_param->partial); + + return 0; + } + + group = kzalloc(sizeof(*group), GFP_KERNEL); + if (!group) { + /* + * The caller will send a response to the hardware. But we do + * need to clean up before leaving, otherwise partial faults + * will be stuck. + */ + ret = -ENOMEM; + goto cleanup_partial; + } + + group->dev = dev; + group->last_fault.fault = *fault; + INIT_LIST_HEAD(&group->faults); + list_add(&group->last_fault.list, &group->faults); + INIT_WORK(&group->work, iopf_handle_group); + + /* See if we have partial faults for this group */ + list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) { + if (iopf->fault.prm.grpid == fault->prm.grpid) + /* Insert *before* the last fault */ + list_move(&iopf->list, &group->faults); + } + + queue_work(iopf_param->queue->wq, &group->work); + return 0; + +cleanup_partial: + list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) { + if (iopf->fault.prm.grpid == fault->prm.grpid) { + list_del(&iopf->list); + kfree(iopf); + } + } + return ret; +} +EXPORT_SYMBOL_GPL(iommu_queue_iopf); + +/** + * iopf_queue_flush_dev - Ensure that all queued faults have been processed + * @dev: the endpoint whose faults need to be flushed. + * + * The IOMMU driver calls this before releasing a PASID, to ensure that all + * pending faults for this PASID have been handled, and won't hit the address + * space of the next process that uses this PASID. The driver must make sure + * that no new fault is added to the queue. In particular it must flush its + * low-level queue before calling this function. + * + * Return: 0 on success and <0 on error. + */ +int iopf_queue_flush_dev(struct device *dev) +{ + int ret = 0; + struct iopf_device_param *iopf_param; + struct dev_iommu *param = dev->iommu; + + if (!param) + return -ENODEV; + + mutex_lock(¶m->lock); + iopf_param = param->iopf_param; + if (iopf_param) + flush_workqueue(iopf_param->queue->wq); + else + ret = -ENODEV; + mutex_unlock(¶m->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(iopf_queue_flush_dev); + +/** + * iopf_queue_discard_partial - Remove all pending partial fault + * @queue: the queue whose partial faults need to be discarded + * + * When the hardware queue overflows, last page faults in a group may have been + * lost and the IOMMU driver calls this to discard all partial faults. The + * driver shouldn't be adding new faults to this queue concurrently. + * + * Return: 0 on success and <0 on error. + */ +int iopf_queue_discard_partial(struct iopf_queue *queue) +{ + struct iopf_fault *iopf, *next; + struct iopf_device_param *iopf_param; + + if (!queue) + return -EINVAL; + + mutex_lock(&queue->lock); + list_for_each_entry(iopf_param, &queue->devices, queue_list) { + list_for_each_entry_safe(iopf, next, &iopf_param->partial, + list) { + list_del(&iopf->list); + kfree(iopf); + } + } + mutex_unlock(&queue->lock); + return 0; +} +EXPORT_SYMBOL_GPL(iopf_queue_discard_partial); + +/** + * iopf_queue_add_device - Add producer to the fault queue + * @queue: IOPF queue + * @dev: device to add + * + * Return: 0 on success and <0 on error. + */ +int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev) +{ + int ret = -EBUSY; + struct iopf_device_param *iopf_param; + struct dev_iommu *param = dev->iommu; + + if (!param) + return -ENODEV; + + iopf_param = kzalloc(sizeof(*iopf_param), GFP_KERNEL); + if (!iopf_param) + return -ENOMEM; + + INIT_LIST_HEAD(&iopf_param->partial); + iopf_param->queue = queue; + iopf_param->dev = dev; + + mutex_lock(&queue->lock); + mutex_lock(¶m->lock); + if (!param->iopf_param) { + list_add(&iopf_param->queue_list, &queue->devices); + param->iopf_param = iopf_param; + ret = 0; + } + mutex_unlock(¶m->lock); + mutex_unlock(&queue->lock); + + if (ret) + kfree(iopf_param); + + return ret; +} +EXPORT_SYMBOL_GPL(iopf_queue_add_device); + +/** + * iopf_queue_remove_device - Remove producer from fault queue + * @queue: IOPF queue + * @dev: device to remove + * + * Caller makes sure that no more faults are reported for this device. + * + * Return: 0 on success and <0 on error. + */ +int iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev) +{ + int ret = -EINVAL; + struct iopf_fault *iopf, *next; + struct iopf_device_param *iopf_param; + struct dev_iommu *param = dev->iommu; + + if (!param || !queue) + return -EINVAL; + + mutex_lock(&queue->lock); + mutex_lock(¶m->lock); + iopf_param = param->iopf_param; + if (iopf_param && iopf_param->queue == queue) { + list_del(&iopf_param->queue_list); + param->iopf_param = NULL; + ret = 0; + } + mutex_unlock(¶m->lock); + mutex_unlock(&queue->lock); + if (ret) + return ret; + + /* Just in case some faults are still stuck */ + list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) + kfree(iopf); + + kfree(iopf_param); + + return 0; +} +EXPORT_SYMBOL_GPL(iopf_queue_remove_device); + +/** + * iopf_queue_alloc - Allocate and initialize a fault queue + * @name: a unique string identifying the queue (for workqueue) + * + * Return: the queue on success and NULL on error. + */ +struct iopf_queue *iopf_queue_alloc(const char *name) +{ + struct iopf_queue *queue; + + queue = kzalloc(sizeof(*queue), GFP_KERNEL); + if (!queue) + return NULL; + + /* + * The WQ is unordered because the low-level handler enqueues faults by + * group. PRI requests within a group have to be ordered, but once + * that's dealt with, the high-level function can handle groups out of + * order. + */ + queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name); + if (!queue->wq) { + kfree(queue); + return NULL; + } + + INIT_LIST_HEAD(&queue->devices); + mutex_init(&queue->lock); + + return queue; +} +EXPORT_SYMBOL_GPL(iopf_queue_alloc); + +/** + * iopf_queue_free - Free IOPF queue + * @queue: queue to free + * + * Counterpart to iopf_queue_alloc(). The driver must not be queuing faults or + * adding/removing devices on this queue anymore. + */ +void iopf_queue_free(struct iopf_queue *queue) +{ + struct iopf_device_param *iopf_param, *next; + + if (!queue) + return; + + list_for_each_entry_safe(iopf_param, next, &queue->devices, queue_list) + iopf_queue_remove_device(queue, iopf_param->dev); + + destroy_workqueue(queue->wq); + kfree(queue); +} +EXPORT_SYMBOL_GPL(iopf_queue_free); |