Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 785 insertions, 0 deletions

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
new file mode 100644
index 000000000..82b07cf94
--- /dev/null
+++ b/drivers/dma/idxd/cdev.c
@@ -0,0 +1,785 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/device.h>
+#include <linux/sched/task.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/iommu.h>
+#include <linux/highmem.h>
+#include <uapi/linux/idxd.h>
+#include <linux/xarray.h>
+#include "registers.h"
+#include "idxd.h"
+
+struct idxd_cdev_context {
+	const char *name;
+	dev_t devt;
+	struct ida minor_ida;
+};
+
+/*
+ * Since user file names are global in DSA devices, define their ida's as
+ * global to avoid conflict file names.
+ */
+static DEFINE_IDA(file_ida);
+
+/*
+ * ictx is an array based off of accelerator types. enum idxd_type
+ * is used as index
+ */
+static struct idxd_cdev_context ictx[IDXD_TYPE_MAX] = {
+	{ .name = "dsa" },
+	{ .name = "iax" }
+};
+
+struct idxd_user_context {
+	struct idxd_wq *wq;
+	struct task_struct *task;
+	unsigned int pasid;
+	struct mm_struct *mm;
+	unsigned int flags;
+	struct iommu_sva *sva;
+	struct idxd_dev idxd_dev;
+	u64 counters[COUNTER_MAX];
+	int id;
+	pid_t pid;
+};
+
+static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid);
+static void idxd_xa_pasid_remove(struct idxd_user_context *ctx);
+
+static inline struct idxd_user_context *dev_to_uctx(struct device *dev)
+{
+	struct idxd_dev *idxd_dev = confdev_to_idxd_dev(dev);
+
+	return container_of(idxd_dev, struct idxd_user_context, idxd_dev);
+}
+
+static ssize_t cr_faults_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+
+	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULTS]);
+}
+static DEVICE_ATTR_RO(cr_faults);
+
+static ssize_t cr_fault_failures_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+
+	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULT_FAILS]);
+}
+static DEVICE_ATTR_RO(cr_fault_failures);
+
+static ssize_t pid_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+
+	return sysfs_emit(buf, "%u\n", ctx->pid);
+}
+static DEVICE_ATTR_RO(pid);
+
+static struct attribute *cdev_file_attributes[] = {
+	&dev_attr_cr_faults.attr,
+	&dev_attr_cr_fault_failures.attr,
+	&dev_attr_pid.attr,
+	NULL
+};
+
+static umode_t cdev_file_attr_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, typeof(*dev), kobj);
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+	struct idxd_wq *wq = ctx->wq;
+
+	if (!wq_pasid_enabled(wq))
+		return 0;
+
+	return a->mode;
+}
+
+static const struct attribute_group cdev_file_attribute_group = {
+	.attrs = cdev_file_attributes,
+	.is_visible = cdev_file_attr_visible,
+};
+
+static const struct attribute_group *cdev_file_attribute_groups[] = {
+	&cdev_file_attribute_group,
+	NULL
+};
+
+static void idxd_file_dev_release(struct device *dev)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_device *idxd = wq->idxd;
+	int rc;
+
+	ida_free(&file_ida, ctx->id);
+
+	/* Wait for in-flight operations to complete. */
+	if (wq_shared(wq)) {
+		idxd_device_drain_pasid(idxd, ctx->pasid);
+	} else {
+		if (device_user_pasid_enabled(idxd)) {
+			/* The wq disable in the disable pasid function will drain the wq */
+			rc = idxd_wq_disable_pasid(wq);
+			if (rc < 0)
+				dev_err(dev, "wq disable pasid failed.\n");
+		} else {
+			idxd_wq_drain(wq);
+		}
+	}
+
+	if (ctx->sva) {
+		idxd_cdev_evl_drain_pasid(wq, ctx->pasid);
+		iommu_sva_unbind_device(ctx->sva);
+		idxd_xa_pasid_remove(ctx);
+	}
+	kfree(ctx);
+	mutex_lock(&wq->wq_lock);
+	idxd_wq_put(wq);
+	mutex_unlock(&wq->wq_lock);
+}
+
+static const struct device_type idxd_cdev_file_type = {
+	.name = "idxd_file",
+	.release = idxd_file_dev_release,
+	.groups = cdev_file_attribute_groups,
+};
+
+static void idxd_cdev_dev_release(struct device *dev)
+{
+	struct idxd_cdev *idxd_cdev = dev_to_cdev(dev);
+
+	kfree(idxd_cdev);
+}
+
+static const struct device_type idxd_cdev_device_type = {
+	.name = "idxd_cdev",
+	.release = idxd_cdev_dev_release,
+};
+
+static inline struct idxd_cdev *inode_idxd_cdev(struct inode *inode)
+{
+	struct cdev *cdev = inode->i_cdev;
+
+	return container_of(cdev, struct idxd_cdev, cdev);
+}
+
+static inline struct idxd_wq *inode_wq(struct inode *inode)
+{
+	struct idxd_cdev *idxd_cdev = inode_idxd_cdev(inode);
+
+	return idxd_cdev->wq;
+}
+
+static void idxd_xa_pasid_remove(struct idxd_user_context *ctx)
+{
+	struct idxd_wq *wq = ctx->wq;
+	void *ptr;
+
+	mutex_lock(&wq->uc_lock);
+	ptr = xa_cmpxchg(&wq->upasid_xa, ctx->pasid, ctx, NULL, GFP_KERNEL);
+	if (ptr != (void *)ctx)
+		dev_warn(&wq->idxd->pdev->dev, "xarray cmpxchg failed for pasid %u\n",
+			 ctx->pasid);
+	mutex_unlock(&wq->uc_lock);
+}
+
+void idxd_user_counter_increment(struct idxd_wq *wq, u32 pasid, int index)
+{
+	struct idxd_user_context *ctx;
+
+	if (index >= COUNTER_MAX)
+		return;
+
+	mutex_lock(&wq->uc_lock);
+	ctx = xa_load(&wq->upasid_xa, pasid);
+	if (!ctx) {
+		mutex_unlock(&wq->uc_lock);
+		return;
+	}
+	ctx->counters[index]++;
+	mutex_unlock(&wq->uc_lock);
+}
+
+static int idxd_cdev_open(struct inode *inode, struct file *filp)
+{
+	struct idxd_user_context *ctx;
+	struct idxd_device *idxd;
+	struct idxd_wq *wq;
+	struct device *dev, *fdev;
+	int rc = 0;
+	struct iommu_sva *sva = NULL;
+	unsigned int pasid;
+	struct idxd_cdev *idxd_cdev;
+
+	wq = inode_wq(inode);
+	idxd = wq->idxd;
+	dev = &idxd->pdev->dev;
+
+	dev_dbg(dev, "%s called: %d\n", __func__, idxd_wq_refcount(wq));
+
+	ctx = kzalloc_obj(*ctx);
+	if (!ctx)
+		return -ENOMEM;
+
+	mutex_lock(&wq->wq_lock);
+
+	if (idxd_wq_refcount(wq) > 0 && wq_dedicated(wq)) {
+		rc = -EBUSY;
+		goto failed;
+	}
+
+	ctx->wq = wq;
+	filp->private_data = ctx;
+	ctx->pid = current->pid;
+
+	if (device_user_pasid_enabled(idxd)) {
+		sva = iommu_sva_bind_device(dev, current->mm);
+		if (IS_ERR(sva)) {
+			rc = PTR_ERR(sva);
+			dev_err(dev, "pasid allocation failed: %d\n", rc);
+			goto failed;
+		}
+
+		pasid = iommu_sva_get_pasid(sva);
+		if (pasid == IOMMU_PASID_INVALID) {
+			rc = -EINVAL;
+			goto failed_get_pasid;
+		}
+
+		ctx->sva = sva;
+		ctx->pasid = pasid;
+		ctx->mm = current->mm;
+
+		mutex_lock(&wq->uc_lock);
+		rc = xa_insert(&wq->upasid_xa, pasid, ctx, GFP_KERNEL);
+		mutex_unlock(&wq->uc_lock);
+		if (rc < 0)
+			dev_warn(dev, "PASID entry already exist in xarray.\n");
+
+		if (wq_dedicated(wq)) {
+			rc = idxd_wq_set_pasid(wq, pasid);
+			if (rc < 0) {
+				dev_err(dev, "wq set pasid failed: %d\n", rc);
+				goto failed_set_pasid;
+			}
+		}
+	}
+
+	idxd_cdev = wq->idxd_cdev;
+	ctx->id = ida_alloc(&file_ida, GFP_KERNEL);
+	if (ctx->id < 0) {
+		dev_warn(dev, "ida alloc failure\n");
+		goto failed_ida;
+	}
+	ctx->idxd_dev.type  = IDXD_DEV_CDEV_FILE;
+	fdev = user_ctx_dev(ctx);
+	device_initialize(fdev);
+	fdev->parent = cdev_dev(idxd_cdev);
+	fdev->bus = &dsa_bus_type;
+	fdev->type = &idxd_cdev_file_type;
+	idxd_wq_get(wq);
+
+	rc = dev_set_name(fdev, "file%d", ctx->id);
+	if (rc < 0) {
+		dev_warn(dev, "set name failure\n");
+		goto failed_dev_name;
+	}
+
+	rc = device_add(fdev);
+	if (rc < 0) {
+		dev_warn(dev, "file device add failure\n");
+		goto failed_dev_add;
+	}
+
+	mutex_unlock(&wq->wq_lock);
+	return 0;
+
+failed_dev_add:
+failed_dev_name:
+	mutex_unlock(&wq->wq_lock);
+	put_device(fdev);
+	return rc;
+failed_ida:
+failed_set_pasid:
+	if (device_user_pasid_enabled(idxd))
+		idxd_xa_pasid_remove(ctx);
+failed_get_pasid:
+	if (device_user_pasid_enabled(idxd) && !IS_ERR_OR_NULL(sva))
+		iommu_sva_unbind_device(sva);
+failed:
+	mutex_unlock(&wq->wq_lock);
+	kfree(ctx);
+	return rc;
+}
+
+static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid)
+{
+	struct idxd_device *idxd = wq->idxd;
+	struct idxd_evl *evl = idxd->evl;
+	union evl_status_reg status;
+	u16 h, t, size;
+	int ent_size = evl_ent_size(idxd);
+	struct __evl_entry *entry_head;
+
+	if (!evl)
+		return;
+
+	mutex_lock(&evl->lock);
+	status.bits = ioread64(idxd->reg_base + IDXD_EVLSTATUS_OFFSET);
+	t = status.tail;
+	h = status.head;
+	size = evl->size;
+
+	while (h != t) {
+		entry_head = (struct __evl_entry *)(evl->log + (h * ent_size));
+		if (entry_head->pasid == pasid && entry_head->wq_idx == wq->id)
+			set_bit(h, evl->bmap);
+		h = (h + 1) % size;
+	}
+	if (wq->wq)
+		drain_workqueue(wq->wq);
+
+	mutex_unlock(&evl->lock);
+}
+
+static int idxd_cdev_release(struct inode *node, struct file *filep)
+{
+	struct idxd_user_context *ctx = filep->private_data;
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_device *idxd = wq->idxd;
+	struct device *dev = &idxd->pdev->dev;
+
+	dev_dbg(dev, "%s called\n", __func__);
+	filep->private_data = NULL;
+
+	device_unregister(user_ctx_dev(ctx));
+
+	return 0;
+}
+
+static int check_vma(struct idxd_wq *wq, struct vm_area_struct *vma,
+		     const char *func)
+{
+	struct device *dev = &wq->idxd->pdev->dev;
+
+	if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
+		dev_info_ratelimited(dev,
+				     "%s: %s: mapping too large: %lu\n",
+				     current->comm, func,
+				     vma->vm_end - vma->vm_start);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int idxd_cdev_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct idxd_user_context *ctx = filp->private_data;
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_device *idxd = wq->idxd;
+	struct pci_dev *pdev = idxd->pdev;
+	phys_addr_t base = pci_resource_start(pdev, IDXD_WQ_BAR);
+	unsigned long pfn;
+	int rc;
+
+	dev_dbg(&pdev->dev, "%s called\n", __func__);
+
+	/*
+	 * Due to an erratum in some of the devices supported by the driver,
+	 * direct user submission to the device can be unsafe.
+	 * (See the INTEL-SA-01084 security advisory)
+	 *
+	 * For the devices that exhibit this behavior, require that the user
+	 * has CAP_SYS_RAWIO capabilities.
+	 */
+	if (!idxd->user_submission_safe && !capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
+	if (current->mm != ctx->mm)
+		return -EPERM;
+
+	rc = check_vma(wq, vma, __func__);
+	if (rc < 0)
+		return rc;
+
+	vm_flags_set(vma, VM_DONTCOPY);
+	pfn = (base + idxd_get_wq_portal_full_offset(wq->id,
+				IDXD_PORTAL_LIMITED)) >> PAGE_SHIFT;
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	vma->vm_private_data = ctx;
+
+	return io_remap_pfn_range(vma, vma->vm_start, pfn, PAGE_SIZE,
+			vma->vm_page_prot);
+}
+
+static int idxd_submit_user_descriptor(struct idxd_user_context *ctx,
+				       struct dsa_hw_desc __user *udesc)
+{
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_dev *idxd_dev = &wq->idxd->idxd_dev;
+	const uint64_t comp_addr_align = is_dsa_dev(idxd_dev) ? 0x20 : 0x40;
+	void __iomem *portal = idxd_wq_portal_addr(wq);
+	struct dsa_hw_desc descriptor __aligned(64);
+	int rc;
+
+	rc = copy_from_user(&descriptor, udesc, sizeof(descriptor));
+	if (rc)
+		return -EFAULT;
+
+	/*
+	 * DSA devices are capable of indirect ("batch") command submission.
+	 * On devices where direct user submissions are not safe, we cannot
+	 * allow this since there is no good way for us to verify these
+	 * indirect commands. Narrow the restriction of operations with the
+	 * BATCH opcode to only DSA version 1 devices.
+	 */
+	if (is_dsa_dev(idxd_dev) && descriptor.opcode == DSA_OPCODE_BATCH &&
+	    wq->idxd->hw.version == DEVICE_VERSION_1 &&
+	    !wq->idxd->user_submission_safe)
+		return -EINVAL;
+	/*
+	 * As per the programming specification, the completion address must be
+	 * aligned to 32 or 64 bytes. If this is violated the hardware
+	 * engine can get very confused (security issue).
+	 */
+	if (!IS_ALIGNED(descriptor.completion_addr, comp_addr_align))
+		return -EINVAL;
+
+	if (wq_dedicated(wq))
+		iosubmit_cmds512(portal, &descriptor, 1);
+	else {
+		descriptor.priv = 0;
+		descriptor.pasid = ctx->pasid;
+		rc = idxd_enqcmds(wq, portal, &descriptor);
+		if (rc < 0)
+			return rc;
+	}
+
+	return 0;
+}
+
+static ssize_t idxd_cdev_write(struct file *filp, const char __user *buf, size_t len,
+			       loff_t *unused)
+{
+	struct dsa_hw_desc __user *udesc = (struct dsa_hw_desc __user *)buf;
+	struct idxd_user_context *ctx = filp->private_data;
+	ssize_t written = 0;
+	int i;
+
+	if (current->mm != ctx->mm)
+		return -EPERM;
+
+	for (i = 0; i < len/sizeof(struct dsa_hw_desc); i++) {
+		int rc = idxd_submit_user_descriptor(ctx, udesc + i);
+
+		if (rc)
+			return written ? written : rc;
+
+		written += sizeof(struct dsa_hw_desc);
+	}
+
+	return written;
+}
+
+static __poll_t idxd_cdev_poll(struct file *filp,
+			       struct poll_table_struct *wait)
+{
+	struct idxd_user_context *ctx = filp->private_data;
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_device *idxd = wq->idxd;
+	__poll_t out = 0;
+
+	if (current->mm != ctx->mm)
+		return POLLNVAL;
+
+	poll_wait(filp, &wq->err_queue, wait);
+	spin_lock(&idxd->dev_lock);
+	if (idxd->sw_err.valid)
+		out = EPOLLIN | EPOLLRDNORM;
+	spin_unlock(&idxd->dev_lock);
+
+	return out;
+}
+
+static const struct file_operations idxd_cdev_fops = {
+	.owner = THIS_MODULE,
+	.open = idxd_cdev_open,
+	.release = idxd_cdev_release,
+	.mmap = idxd_cdev_mmap,
+	.write = idxd_cdev_write,
+	.poll = idxd_cdev_poll,
+};
+
+int idxd_cdev_get_major(struct idxd_device *idxd)
+{
+	return MAJOR(ictx[idxd->data->type].devt);
+}
+
+int idxd_wq_add_cdev(struct idxd_wq *wq)
+{
+	struct idxd_device *idxd = wq->idxd;
+	struct idxd_cdev *idxd_cdev;
+	struct cdev *cdev;
+	struct device *dev;
+	struct idxd_cdev_context *cdev_ctx;
+	int rc, minor;
+
+	idxd_cdev = kzalloc_obj(*idxd_cdev);
+	if (!idxd_cdev)
+		return -ENOMEM;
+
+	idxd_cdev->idxd_dev.type = IDXD_DEV_CDEV;
+	idxd_cdev->wq = wq;
+	cdev = &idxd_cdev->cdev;
+	dev = cdev_dev(idxd_cdev);
+	cdev_ctx = &ictx[wq->idxd->data->type];
+	minor = ida_alloc_max(&cdev_ctx->minor_ida, MINORMASK, GFP_KERNEL);
+	if (minor < 0) {
+		kfree(idxd_cdev);
+		return minor;
+	}
+	idxd_cdev->minor = minor;
+
+	device_initialize(dev);
+	dev->parent = wq_confdev(wq);
+	dev->bus = &dsa_bus_type;
+	dev->type = &idxd_cdev_device_type;
+	dev->devt = MKDEV(MAJOR(cdev_ctx->devt), minor);
+
+	rc = dev_set_name(dev, "%s/wq%u.%u", idxd->data->name_prefix, idxd->id, wq->id);
+	if (rc < 0)
+		goto err;
+
+	wq->idxd_cdev = idxd_cdev;
+	cdev_init(cdev, &idxd_cdev_fops);
+	rc = cdev_device_add(cdev, dev);
+	if (rc) {
+		dev_dbg(&wq->idxd->pdev->dev, "cdev_add failed: %d\n", rc);
+		goto err;
+	}
+
+	return 0;
+
+ err:
+	put_device(dev);
+	wq->idxd_cdev = NULL;
+	return rc;
+}
+
+void idxd_wq_del_cdev(struct idxd_wq *wq)
+{
+	struct idxd_cdev_context *cdev_ctx;
+	struct idxd_cdev *idxd_cdev;
+
+	idxd_cdev = wq->idxd_cdev;
+	wq->idxd_cdev = NULL;
+	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
+
+	cdev_ctx = &ictx[wq->idxd->data->type];
+	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
+	put_device(cdev_dev(idxd_cdev));
+}
+
+static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
+{
+	struct device *dev = &idxd_dev->conf_dev;
+	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
+	struct idxd_device *idxd = wq->idxd;
+	int rc;
+
+	if (idxd->state != IDXD_DEV_ENABLED)
+		return -ENXIO;
+
+	mutex_lock(&wq->wq_lock);
+
+	if (!idxd_wq_driver_name_match(wq, dev)) {
+		idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
+		rc = -ENODEV;
+		goto wq_err;
+	}
+
+	/*
+	 * User type WQ is enabled only when SVA is enabled for two reasons:
+	 *   - If no IOMMU or IOMMU Passthrough without SVA, userspace
+	 *     can directly access physical address through the WQ.
+	 *   - The IDXD cdev driver does not provide any ways to pin
+	 *     user pages and translate the address from user VA to IOVA or
+	 *     PA without IOMMU SVA. Therefore the application has no way
+	 *     to instruct the device to perform DMA function. This makes
+	 *     the cdev not usable for normal application usage.
+	 */
+	if (!device_user_pasid_enabled(idxd)) {
+		idxd->cmd_status = IDXD_SCMD_WQ_USER_NO_IOMMU;
+		dev_dbg(&idxd->pdev->dev,
+			"User type WQ cannot be enabled without SVA.\n");
+
+		rc = -EOPNOTSUPP;
+		goto wq_err;
+	}
+
+	wq->wq = create_workqueue(dev_name(wq_confdev(wq)));
+	if (!wq->wq) {
+		rc = -ENOMEM;
+		goto wq_err;
+	}
+
+	wq->type = IDXD_WQT_USER;
+	rc = idxd_drv_enable_wq(wq);
+	if (rc < 0)
+		goto err;
+
+	rc = idxd_wq_add_cdev(wq);
+	if (rc < 0) {
+		idxd->cmd_status = IDXD_SCMD_CDEV_ERR;
+		goto err_cdev;
+	}
+
+	idxd->cmd_status = 0;
+	mutex_unlock(&wq->wq_lock);
+	return 0;
+
+err_cdev:
+	idxd_drv_disable_wq(wq);
+err:
+	destroy_workqueue(wq->wq);
+	wq->type = IDXD_WQT_NONE;
+wq_err:
+	mutex_unlock(&wq->wq_lock);
+	return rc;
+}
+
+static void idxd_user_drv_remove(struct idxd_dev *idxd_dev)
+{
+	struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
+
+	mutex_lock(&wq->wq_lock);
+	idxd_wq_del_cdev(wq);
+	idxd_drv_disable_wq(wq);
+	wq->type = IDXD_WQT_NONE;
+	destroy_workqueue(wq->wq);
+	wq->wq = NULL;
+	mutex_unlock(&wq->wq_lock);
+}
+
+static enum idxd_dev_type dev_types[] = {
+	IDXD_DEV_WQ,
+	IDXD_DEV_NONE,
+};
+
+struct idxd_device_driver idxd_user_drv = {
+	.probe = idxd_user_drv_probe,
+	.remove = idxd_user_drv_remove,
+	.name = "user",
+	.type = dev_types,
+};
+EXPORT_SYMBOL_GPL(idxd_user_drv);
+
+int idxd_cdev_register(void)
+{
+	int rc, i;
+
+	for (i = 0; i < IDXD_TYPE_MAX; i++) {
+		ida_init(&ictx[i].minor_ida);
+		rc = alloc_chrdev_region(&ictx[i].devt, 0, MINORMASK,
+					 ictx[i].name);
+		if (rc)
+			goto err_free_chrdev_region;
+	}
+
+	return 0;
+
+err_free_chrdev_region:
+	for (i--; i >= 0; i--)
+		unregister_chrdev_region(ictx[i].devt, MINORMASK);
+
+	return rc;
+}
+
+void idxd_cdev_remove(void)
+{
+	int i;
+
+	for (i = 0; i < IDXD_TYPE_MAX; i++) {
+		unregister_chrdev_region(ictx[i].devt, MINORMASK);
+		ida_destroy(&ictx[i].minor_ida);
+	}
+}
+
+/**
+ * idxd_copy_cr - copy completion record to user address space found by wq and
+ *		  PASID
+ * @wq:		work queue
+ * @pasid:	PASID
+ * @addr:	user fault address to write
+ * @cr:		completion record
+ * @len:	number of bytes to copy
+ *
+ * This is called by a work that handles completion record fault.
+ *
+ * Return: number of bytes copied.
+ */
+int idxd_copy_cr(struct idxd_wq *wq, ioasid_t pasid, unsigned long addr,
+		 void *cr, int len)
+{
+	struct device *dev = &wq->idxd->pdev->dev;
+	int left = len, status_size = 1;
+	struct idxd_user_context *ctx;
+	struct mm_struct *mm;
+
+	mutex_lock(&wq->uc_lock);
+
+	ctx = xa_load(&wq->upasid_xa, pasid);
+	if (!ctx) {
+		dev_warn(dev, "No user context\n");
+		goto out;
+	}
+
+	mm = ctx->mm;
+	/*
+	 * The completion record fault handling work is running in kernel
+	 * thread context. It temporarily switches to the mm to copy cr
+	 * to addr in the mm.
+	 */
+	kthread_use_mm(mm);
+	left = copy_to_user((void __user *)addr + status_size, cr + status_size,
+			    len - status_size);
+	/*
+	 * Copy status only after the rest of completion record is copied
+	 * successfully so that the user gets the complete completion record
+	 * when a non-zero status is polled.
+	 */
+	if (!left) {
+		u8 status;
+
+		/*
+		 * Ensure that the completion record's status field is written
+		 * after the rest of the completion record has been written.
+		 * This ensures that the user receives the correct completion
+		 * record information once polling for a non-zero status.
+		 */
+		wmb();
+		status = *(u8 *)cr;
+		if (put_user(status, (u8 __user *)addr))
+			left += status_size;
+	} else {
+		left += status_size;
+	}
+	kthread_unuse_mm(mm);
+
+out:
+	mutex_unlock(&wq->uc_lock);
+
+	return len - left;
+}