#include <rdma/ib_umem.h>
#include <rdma/ib_umem_odp.h>
+static void ib_umem_notifier_start_account(struct ib_umem *item)
+{
+ mutex_lock(&item->odp_data->umem_mutex);
+
+ /* Only update private counters for this umem if it has them.
+ * Otherwise skip it. All page faults will be delayed for this umem. */
+ if (item->odp_data->mn_counters_active) {
+ int notifiers_count = item->odp_data->notifiers_count++;
+
+ if (notifiers_count == 0)
+ /* Initialize the completion object for waiting on
+ * notifiers. Since notifier_count is zero, no one
+ * should be waiting right now. */
+ reinit_completion(&item->odp_data->notifier_completion);
+ }
+ mutex_unlock(&item->odp_data->umem_mutex);
+}
+
+static void ib_umem_notifier_end_account(struct ib_umem *item)
+{
+ mutex_lock(&item->odp_data->umem_mutex);
+
+ /* Only update private counters for this umem if it has them.
+ * Otherwise skip it. All page faults will be delayed for this umem. */
+ if (item->odp_data->mn_counters_active) {
+ /*
+ * This sequence increase will notify the QP page fault that
+ * the page that is going to be mapped in the spte could have
+ * been freed.
+ */
+ ++item->odp_data->notifiers_seq;
+ if (--item->odp_data->notifiers_count == 0)
+ complete_all(&item->odp_data->notifier_completion);
+ }
+ mutex_unlock(&item->odp_data->umem_mutex);
+}
+
+/* Account for a new mmu notifier in an ib_ucontext. */
+static void ib_ucontext_notifier_start_account(struct ib_ucontext *context)
+{
+ atomic_inc(&context->notifier_count);
+}
+
+/* Account for a terminating mmu notifier in an ib_ucontext.
+ *
+ * Must be called with the ib_ucontext->umem_rwsem semaphore unlocked, since
+ * the function takes the semaphore itself. */
+static void ib_ucontext_notifier_end_account(struct ib_ucontext *context)
+{
+ int zero_notifiers = atomic_dec_and_test(&context->notifier_count);
+
+ if (zero_notifiers &&
+ !list_empty(&context->no_private_counters)) {
+ /* No currently running mmu notifiers. Now is the chance to
+ * add private accounting to all previously added umems. */
+ struct ib_umem_odp *odp_data, *next;
+
+ /* Prevent concurrent mmu notifiers from working on the
+ * no_private_counters list. */
+ down_write(&context->umem_rwsem);
+
+ /* Read the notifier_count again, with the umem_rwsem
+ * semaphore taken for write. */
+ if (!atomic_read(&context->notifier_count)) {
+ list_for_each_entry_safe(odp_data, next,
+ &context->no_private_counters,
+ no_private_counters) {
+ mutex_lock(&odp_data->umem_mutex);
+ odp_data->mn_counters_active = true;
+ list_del(&odp_data->no_private_counters);
+ complete_all(&odp_data->notifier_completion);
+ mutex_unlock(&odp_data->umem_mutex);
+ }
+ }
+
+ up_write(&context->umem_rwsem);
+ }
+}
+
+static int ib_umem_notifier_release_trampoline(struct ib_umem *item, u64 start,
+ u64 end, void *cookie) {
+ /*
+ * Increase the number of notifiers running, to
+ * prevent any further fault handling on this MR.
+ */
+ ib_umem_notifier_start_account(item);
+ item->odp_data->dying = 1;
+ /* Make sure that the fact the umem is dying is out before we release
+ * all pending page faults. */
+ smp_wmb();
+ complete_all(&item->odp_data->notifier_completion);
+ item->context->invalidate_range(item, ib_umem_start(item),
+ ib_umem_end(item));
+ return 0;
+}
+
+static void ib_umem_notifier_release(struct mmu_notifier *mn,
+ struct mm_struct *mm)
+{
+ struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+
+ if (!context->invalidate_range)
+ return;
+
+ ib_ucontext_notifier_start_account(context);
+ down_read(&context->umem_rwsem);
+ rbt_ib_umem_for_each_in_range(&context->umem_tree, 0,
+ ULLONG_MAX,
+ ib_umem_notifier_release_trampoline,
+ NULL);
+ up_read(&context->umem_rwsem);
+}
+
+static int invalidate_page_trampoline(struct ib_umem *item, u64 start,
+ u64 end, void *cookie)
+{
+ ib_umem_notifier_start_account(item);
+ item->context->invalidate_range(item, start, start + PAGE_SIZE);
+ ib_umem_notifier_end_account(item);
+ return 0;
+}
+
+static void ib_umem_notifier_invalidate_page(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long address)
+{
+ struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+
+ if (!context->invalidate_range)
+ return;
+
+ ib_ucontext_notifier_start_account(context);
+ down_read(&context->umem_rwsem);
+ rbt_ib_umem_for_each_in_range(&context->umem_tree, address,
+ address + PAGE_SIZE,
+ invalidate_page_trampoline, NULL);
+ up_read(&context->umem_rwsem);
+ ib_ucontext_notifier_end_account(context);
+}
+
+static int invalidate_range_start_trampoline(struct ib_umem *item, u64 start,
+ u64 end, void *cookie)
+{
+ ib_umem_notifier_start_account(item);
+ item->context->invalidate_range(item, start, end);
+ return 0;
+}
+
+static void ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+
+ if (!context->invalidate_range)
+ return;
+
+ ib_ucontext_notifier_start_account(context);
+ down_read(&context->umem_rwsem);
+ rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
+ end,
+ invalidate_range_start_trampoline, NULL);
+ up_read(&context->umem_rwsem);
+}
+
+static int invalidate_range_end_trampoline(struct ib_umem *item, u64 start,
+ u64 end, void *cookie)
+{
+ ib_umem_notifier_end_account(item);
+ return 0;
+}
+
+static void ib_umem_notifier_invalidate_range_end(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+
+ if (!context->invalidate_range)
+ return;
+
+ down_read(&context->umem_rwsem);
+ rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
+ end,
+ invalidate_range_end_trampoline, NULL);
+ up_read(&context->umem_rwsem);
+ ib_ucontext_notifier_end_account(context);
+}
+
+static struct mmu_notifier_ops ib_umem_notifiers = {
+ .release = ib_umem_notifier_release,
+ .invalidate_page = ib_umem_notifier_invalidate_page,
+ .invalidate_range_start = ib_umem_notifier_invalidate_range_start,
+ .invalidate_range_end = ib_umem_notifier_invalidate_range_end,
+};
+
int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem)
{
int ret_val;
struct pid *our_pid;
+ struct mm_struct *mm = get_task_mm(current);
+
+ if (!mm)
+ return -EINVAL;
/* Prevent creating ODP MRs in child processes */
rcu_read_lock();
our_pid = get_task_pid(current->group_leader, PIDTYPE_PID);
rcu_read_unlock();
put_pid(our_pid);
- if (context->tgid != our_pid)
- return -EINVAL;
+ if (context->tgid != our_pid) {
+ ret_val = -EINVAL;
+ goto out_mm;
+ }
umem->hugetlb = 0;
umem->odp_data = kzalloc(sizeof(*umem->odp_data), GFP_KERNEL);
- if (!umem->odp_data)
- return -ENOMEM;
+ if (!umem->odp_data) {
+ ret_val = -ENOMEM;
+ goto out_mm;
+ }
+ umem->odp_data->umem = umem;
mutex_init(&umem->odp_data->umem_mutex);
+ init_completion(&umem->odp_data->notifier_completion);
+
umem->odp_data->page_list = vzalloc(ib_umem_num_pages(umem) *
sizeof(*umem->odp_data->page_list));
if (!umem->odp_data->page_list) {
goto out_page_list;
}
+ /*
+ * When using MMU notifiers, we will get a
+ * notification before the "current" task (and MM) is
+ * destroyed. We use the umem_rwsem semaphore to synchronize.
+ */
+ down_write(&context->umem_rwsem);
+ context->odp_mrs_count++;
+ if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
+ rbt_ib_umem_insert(&umem->odp_data->interval_tree,
+ &context->umem_tree);
+ if (likely(!atomic_read(&context->notifier_count)))
+ umem->odp_data->mn_counters_active = true;
+ else
+ list_add(&umem->odp_data->no_private_counters,
+ &context->no_private_counters);
+ downgrade_write(&context->umem_rwsem);
+
+ if (context->odp_mrs_count == 1) {
+ /*
+ * Note that at this point, no MMU notifier is running
+ * for this context!
+ */
+ atomic_set(&context->notifier_count, 0);
+ INIT_HLIST_NODE(&context->mn.hlist);
+ context->mn.ops = &ib_umem_notifiers;
+ /*
+ * Lock-dep detects a false positive for mmap_sem vs.
+ * umem_rwsem, due to not grasping downgrade_write correctly.
+ */
+ lockdep_off();
+ ret_val = mmu_notifier_register(&context->mn, mm);
+ lockdep_on();
+ if (ret_val) {
+ pr_err("Failed to register mmu_notifier %d\n", ret_val);
+ ret_val = -EBUSY;
+ goto out_mutex;
+ }
+ }
+
+ up_read(&context->umem_rwsem);
+
+ /*
+ * Note that doing an mmput can cause a notifier for the relevant mm.
+ * If the notifier is called while we hold the umem_rwsem, this will
+ * cause a deadlock. Therefore, we release the reference only after we
+ * released the semaphore.
+ */
+ mmput(mm);
return 0;
+out_mutex:
+ up_read(&context->umem_rwsem);
+ vfree(umem->odp_data->dma_list);
out_page_list:
vfree(umem->odp_data->page_list);
out_odp_data:
kfree(umem->odp_data);
+out_mm:
+ mmput(mm);
return ret_val;
}
void ib_umem_odp_release(struct ib_umem *umem)
{
+ struct ib_ucontext *context = umem->context;
+
/*
* Ensure that no more pages are mapped in the umem.
*
ib_umem_odp_unmap_dma_pages(umem, ib_umem_start(umem),
ib_umem_end(umem));
+ down_write(&context->umem_rwsem);
+ if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
+ rbt_ib_umem_remove(&umem->odp_data->interval_tree,
+ &context->umem_tree);
+ context->odp_mrs_count--;
+ if (!umem->odp_data->mn_counters_active) {
+ list_del(&umem->odp_data->no_private_counters);
+ complete_all(&umem->odp_data->notifier_completion);
+ }
+
+ /*
+ * Downgrade the lock to a read lock. This ensures that the notifiers
+ * (who lock the mutex for reading) will be able to finish, and we
+ * will be able to enventually obtain the mmu notifiers SRCU. Note
+ * that since we are doing it atomically, no other user could register
+ * and unregister while we do the check.
+ */
+ downgrade_write(&context->umem_rwsem);
+ if (!context->odp_mrs_count) {
+ struct task_struct *owning_process = NULL;
+ struct mm_struct *owning_mm = NULL;
+
+ owning_process = get_pid_task(context->tgid,
+ PIDTYPE_PID);
+ if (owning_process == NULL)
+ /*
+ * The process is already dead, notifier were removed
+ * already.
+ */
+ goto out;
+
+ owning_mm = get_task_mm(owning_process);
+ if (owning_mm == NULL)
+ /*
+ * The process' mm is already dead, notifier were
+ * removed already.
+ */
+ goto out_put_task;
+ mmu_notifier_unregister(&context->mn, owning_mm);
+
+ mmput(owning_mm);
+
+out_put_task:
+ put_task_struct(owning_process);
+ }
+out:
+ up_read(&context->umem_rwsem);
+
vfree(umem->odp_data->dma_list);
vfree(umem->odp_data->page_list);
kfree(umem->odp_data);
* the sequence number is taken from
* umem->odp_data->notifiers_seq.
*
- * The function returns -EFAULT if the DMA mapping operation fails.
+ * The function returns -EFAULT if the DMA mapping operation fails. It returns
+ * -EAGAIN if a concurrent invalidation prevents us from updating the page.
*
* The page is released via put_page even if the operation failed. For
* on-demand pinning, the page is released whenever it isn't stored in the
static int ib_umem_odp_map_dma_single_page(
struct ib_umem *umem,
int page_index,
+ u64 base_virt_addr,
struct page *page,
u64 access_mask,
unsigned long current_seq)
struct ib_device *dev = umem->context->device;
dma_addr_t dma_addr;
int stored_page = 0;
+ int remove_existing_mapping = 0;
int ret = 0;
mutex_lock(&umem->odp_data->umem_mutex);
+ /*
+ * Note: we avoid writing if seq is different from the initial seq, to
+ * handle case of a racing notifier. This check also allows us to bail
+ * early if we have a notifier running in parallel with us.
+ */
+ if (ib_umem_mmu_notifier_retry(umem, current_seq)) {
+ ret = -EAGAIN;
+ goto out;
+ }
if (!(umem->odp_data->dma_list[page_index])) {
dma_addr = ib_dma_map_page(dev,
page,
} else {
pr_err("error: got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n",
umem->odp_data->page_list[page_index], page);
+ /* Better remove the mapping now, to prevent any further
+ * damage. */
+ remove_existing_mapping = 1;
}
out:
mutex_unlock(&umem->odp_data->umem_mutex);
- if (!stored_page)
+ /* On Demand Paging - avoid pinning the page */
+ if (umem->context->invalidate_range || !stored_page)
put_page(page);
+ if (remove_existing_mapping && umem->context->invalidate_range) {
+ invalidate_page_trampoline(
+ umem,
+ base_virt_addr + (page_index * PAGE_SIZE),
+ base_virt_addr + ((page_index+1)*PAGE_SIZE),
+ NULL);
+ ret = -EAGAIN;
+ }
+
return ret;
}
*
* Returns the number of pages mapped in success, negative error code
* for failure.
+ * An -EAGAIN error code is returned when a concurrent mmu notifier prevents
+ * the function from completing its task.
*
* @umem: the umem to map and pin
* @user_virt: the address from which we need to map.
struct page **local_page_list = NULL;
u64 off;
int j, k, ret = 0, start_idx, npages = 0;
+ u64 base_virt_addr;
if (access_mask == 0)
return -EINVAL;
off = user_virt & (~PAGE_MASK);
user_virt = user_virt & PAGE_MASK;
+ base_virt_addr = user_virt;
bcnt += off; /* Charge for the first page offset as well. */
owning_process = get_pid_task(umem->context->tgid, PIDTYPE_PID);
user_virt += npages << PAGE_SHIFT;
for (j = 0; j < npages; ++j) {
ret = ib_umem_odp_map_dma_single_page(
- umem, k, local_page_list[j], access_mask,
- current_seq);
+ umem, k, base_virt_addr, local_page_list[j],
+ access_mask, current_seq);
if (ret < 0)
break;
k++;
virt = max_t(u64, virt, ib_umem_start(umem));
bound = min_t(u64, bound, ib_umem_end(umem));
+ /* Note that during the run of this function, the
+ * notifiers_count of the MR is > 0, preventing any racing
+ * faults from completion. We might be racing with other
+ * invalidations, so we must make sure we free each page only
+ * once. */
for (addr = virt; addr < bound; addr += (u64)umem->page_size) {
idx = (addr - ib_umem_start(umem)) / PAGE_SIZE;
mutex_lock(&umem->odp_data->umem_mutex);
ib_dma_unmap_page(dev, dma_addr, PAGE_SIZE,
DMA_BIDIRECTIONAL);
if (dma & ODP_WRITE_ALLOWED_BIT)
- set_page_dirty_lock(head_page);
- put_page(page);
+ /*
+ * set_page_dirty prefers being called with
+ * the page lock. However, MMU notifiers are
+ * called sometimes with and sometimes without
+ * the lock. We rely on the umem_mutex instead
+ * to prevent other mmu notifiers from
+ * continuing and allowing the page mapping to
+ * be removed.
+ */
+ set_page_dirty(head_page);
+ /* on demand pinning support */
+ if (!umem->context->invalidate_range)
+ put_page(page);
+ umem->odp_data->page_list[idx] = NULL;
+ umem->odp_data->dma_list[idx] = 0;
}
mutex_unlock(&umem->odp_data->umem_mutex);
}
--- /dev/null
+/*
+ * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * 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 AUTHORS OR COPYRIGHT HOLDERS
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/interval_tree_generic.h>
+#include <linux/sched.h>
+#include <linux/gfp.h>
+#include <rdma/ib_umem_odp.h>
+
+/*
+ * The ib_umem list keeps track of memory regions for which the HW
+ * device request to receive notification when the related memory
+ * mapping is changed.
+ *
+ * ib_umem_lock protects the list.
+ */
+
+static inline u64 node_start(struct umem_odp_node *n)
+{
+ struct ib_umem_odp *umem_odp =
+ container_of(n, struct ib_umem_odp, interval_tree);
+
+ return ib_umem_start(umem_odp->umem);
+}
+
+/* Note that the representation of the intervals in the interval tree
+ * considers the ending point as contained in the interval, while the
+ * function ib_umem_end returns the first address which is not contained
+ * in the umem.
+ */
+static inline u64 node_last(struct umem_odp_node *n)
+{
+ struct ib_umem_odp *umem_odp =
+ container_of(n, struct ib_umem_odp, interval_tree);
+
+ return ib_umem_end(umem_odp->umem) - 1;
+}
+
+INTERVAL_TREE_DEFINE(struct umem_odp_node, rb, u64, __subtree_last,
+ node_start, node_last, , rbt_ib_umem)
+
+/* @last is not a part of the interval. See comment for function
+ * node_last.
+ */
+int rbt_ib_umem_for_each_in_range(struct rb_root *root,
+ u64 start, u64 last,
+ umem_call_back cb,
+ void *cookie)
+{
+ int ret_val = 0;
+ struct umem_odp_node *node;
+ struct ib_umem_odp *umem;
+
+ if (unlikely(start == last))
+ return ret_val;
+
+ for (node = rbt_ib_umem_iter_first(root, start, last - 1); node;
+ node = rbt_ib_umem_iter_next(node, start, last - 1)) {
+ umem = container_of(node, struct ib_umem_odp, interval_tree);
+ ret_val = cb(umem->umem, start, last, cookie) || ret_val;
+ }
+
+ return ret_val;
+}
projects / users / hch / xfs.git / commitdiff