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Subject[PATCH 33/36] IB/odp/hmm: add core infiniband structure and helper for ODP with HMM.
Date
From: Jérôme Glisse <jglisse@redhat.com>

This add new core infiniband structure and helper to implement ODP (on
demand paging) on top of HMM. We need to retain the tree of ib_umem as
some hardware associate unique identifiant with each umem (or mr) and
only allow hardware page table to be updated using this unique id.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
cc: <linux-rdma@vger.kernel.org>
---
drivers/infiniband/core/umem_odp.c | 148 +++++++++++++++++++++++++++++++++-
drivers/infiniband/core/uverbs_cmd.c | 6 +-
drivers/infiniband/core/uverbs_main.c | 6 ++
include/rdma/ib_umem_odp.h | 28 ++++++-
include/rdma/ib_verbs.h | 17 +++-
5 files changed, 199 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index e55e124..d5d57a8 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -41,9 +41,155 @@
#include <rdma/ib_umem.h>
#include <rdma/ib_umem_odp.h>

+
#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
-#error "CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM not supported at this stage !"
+
+
+static void ib_mirror_destroy(struct kref *kref)
+{
+ struct ib_mirror *ib_mirror;
+ struct ib_device *ib_device;
+
+ ib_mirror = container_of(kref, struct ib_mirror, kref);
+ hmm_mirror_unregister(&ib_mirror->base);
+
+ ib_device = ib_mirror->ib_device;
+ mutex_lock(&ib_device->hmm_mutex);
+ list_del_init(&ib_mirror->list);
+ mutex_unlock(&ib_device->hmm_mutex);
+ kfree(ib_mirror);
+}
+
+void ib_mirror_unref(struct ib_mirror *ib_mirror)
+{
+ if (ib_mirror == NULL)
+ return;
+
+ kref_put(&ib_mirror->kref, ib_mirror_destroy);
+}
+EXPORT_SYMBOL(ib_mirror_unref);
+
+static inline struct ib_mirror *ib_mirror_ref(struct ib_mirror *ib_mirror)
+{
+ if (!ib_mirror || !kref_get_unless_zero(&ib_mirror->kref))
+ return NULL;
+ return ib_mirror;
+}
+
+int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem)
+{
+ struct mm_struct *mm = get_task_mm(current);
+ struct ib_device *ib_device = context->device;
+ struct ib_mirror *ib_mirror;
+ struct pid *our_pid;
+ int ret;
+
+ if (!mm || !ib_device->hmm_ready)
+ return -EINVAL;
+
+ /* FIXME can this really happen ? */
+ if (unlikely(ib_umem_start(umem) == ib_umem_end(umem)))
+ 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) {
+ mmput(mm);
+ return -EINVAL;
+ }
+
+ umem->hugetlb = 0;
+ umem->odp_data = kmalloc(sizeof(*umem->odp_data), GFP_KERNEL);
+ if (umem->odp_data == NULL) {
+ mmput(mm);
+ return -ENOMEM;
+ }
+ umem->odp_data->private = NULL;
+ umem->odp_data->umem = umem;
+
+ mutex_lock(&ib_device->hmm_mutex);
+ /* Is there an existing mirror for this process mm ? */
+ ib_mirror = ib_mirror_ref(context->ib_mirror);
+ if (!ib_mirror)
+ list_for_each_entry(ib_mirror, &ib_device->ib_mirrors, list) {
+ if (ib_mirror->base.hmm->mm != mm)
+ continue;
+ ib_mirror = ib_mirror_ref(ib_mirror);
+ break;
+ }
+
+ if (ib_mirror == NULL ||
+ ib_mirror == list_first_entry(&ib_device->ib_mirrors,
+ struct ib_mirror, list)) {
+ /* We need to create a new mirror. */
+ ib_mirror = kmalloc(sizeof(*ib_mirror), GFP_KERNEL);
+ if (ib_mirror == NULL) {
+ mutex_unlock(&ib_device->hmm_mutex);
+ mmput(mm);
+ return -ENOMEM;
+ }
+ kref_init(&ib_mirror->kref);
+ init_rwsem(&ib_mirror->hmm_mr_rwsem);
+ ib_mirror->umem_tree = RB_ROOT;
+ ib_mirror->ib_device = ib_device;
+
+ ib_mirror->base.device = &ib_device->hmm_dev;
+ ret = hmm_mirror_register(&ib_mirror->base);
+ if (ret) {
+ mutex_unlock(&ib_device->hmm_mutex);
+ kfree(ib_mirror);
+ mmput(mm);
+ return ret;
+ }
+
+ list_add(&ib_mirror->list, &ib_device->ib_mirrors);
+ context->ib_mirror = ib_mirror_ref(ib_mirror);
+ }
+ mutex_unlock(&ib_device->hmm_mutex);
+ umem->odp_data.ib_mirror = ib_mirror;
+
+ down_write(&ib_mirror->umem_rwsem);
+ rbt_ib_umem_insert(&umem->odp_data->interval_tree, &mirror->umem_tree);
+ up_write(&ib_mirror->umem_rwsem);
+
+ mmput(mm);
+ return 0;
+}
+
+void ib_umem_odp_release(struct ib_umem *umem)
+{
+ struct ib_mirror *ib_mirror = umem->odp_data;
+
+ /*
+ * Ensure that no more pages are mapped in the umem.
+ *
+ * It is the driver's responsibility to ensure, before calling us,
+ * that the hardware will not attempt to access the MR any more.
+ */
+
+ /* One optimization to release resources early here would be to call :
+ * hmm_mirror_range_discard(&ib_mirror->base,
+ * ib_umem_start(umem),
+ * ib_umem_end(umem));
+ * But we can have overlapping umem so we would need to only discard
+ * range covered by one and only one umem while holding the umem rwsem.
+ */
+ down_write(&ib_mirror->umem_rwsem);
+ rbt_ib_umem_remove(&umem->odp_data->interval_tree, &mirror->umem_tree);
+ up_write(&ib_mirror->umem_rwsem);
+
+ ib_mirror_unref(ib_mirror);
+ kfree(umem->odp_data);
+ kfree(umem);
+}
+
+
#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
+
+
static void ib_umem_notifier_start_account(struct ib_umem *item)
{
mutex_lock(&item->odp_data->umem_mutex);
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index ccd6bbe..3225ab5 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -337,7 +337,9 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
ucontext->closing = 0;

#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-#ifndef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+ ucontext->ib_mirror = NULL;
+#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
ucontext->umem_tree = RB_ROOT;
init_rwsem(&ucontext->umem_rwsem);
ucontext->odp_mrs_count = 0;
@@ -348,7 +350,7 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
goto err_free;
if (!(dev_attr.device_cap_flags & IB_DEVICE_ON_DEMAND_PAGING))
ucontext->invalidate_range = NULL;
-#endif /* !CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
+#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */

resp.num_comp_vectors = file->device->num_comp_vectors;
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 88cce9b..3f069d7 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -45,6 +45,7 @@
#include <linux/cdev.h>
#include <linux/anon_inodes.h>
#include <linux/slab.h>
+#include <rdma/ib_umem_odp.h>

#include <asm/uaccess.h>

@@ -297,6 +298,11 @@ static int ib_uverbs_cleanup_ucontext(struct ib_uverbs_file *file,
kfree(uobj);
}

+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+ ib_mirror_unref(context->ib_mirror);
+ context->ib_mirror = NULL;
+#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
+
put_pid(context->tgid);

return context->device->dealloc_ucontext(context);
diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index 765aeb3..c7c2670 100644
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -37,6 +37,32 @@
#include <rdma/ib_verbs.h>
#include <linux/interval_tree.h>

+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+/* struct ib_mirror - per process mirror structure for infiniband driver.
+ *
+ * @ib_device: Infiniband device this mirror is associated with.
+ * @base: The hmm base mirror struct.
+ * @kref: Refcount for the structure.
+ * @list: For the list of ib_mirror of a given ib_device.
+ * @umem_tree: Red black tree of ib_umem ordered by virtual address.
+ * @umem_rwsem: Semaphore protecting the reb black tree.
+ *
+ * Because ib_ucontext struct is tie to file descriptor there can be several of
+ * them for a same process, which violate HMM requirement. Hence we create only
+ * one ib_mirror struct per process and have each ib_umem struct reference it.
+ */
+struct ib_mirror {
+ struct ib_device *ib_device;
+ struct hmm_mirror base;
+ struct kref kref;
+ struct list_head list;
+ struct rb_root umem_tree;
+ struct rw_semaphore umem_rwsem;
+};
+
+void ib_mirror_unref(struct ib_mirror *ib_mirror);
+#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
+
struct umem_odp_node {
u64 __subtree_last;
struct rb_node rb;
@@ -44,7 +70,7 @@ struct umem_odp_node {

struct ib_umem_odp {
#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
-#error "CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM not supported at this stage !"
+ struct ib_mirror *ib_mirror;
#else
/*
* An array of the pages included in the on-demand paging umem.
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 7b00d30..83da1bd 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -49,6 +49,9 @@
#include <linux/scatterlist.h>
#include <linux/workqueue.h>
#include <uapi/linux/if_ether.h>
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+#include <linux/hmm.h>
+#endif

#include <linux/atomic.h>
#include <linux/mmu_notifier.h>
@@ -1157,7 +1160,9 @@ struct ib_ucontext {

struct pid *tgid;
#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-#ifndef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+ struct ib_mirror *ib_mirror;
+#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
struct rb_root umem_tree;
/*
* Protects .umem_rbroot and tree, as well as odp_mrs_count and
@@ -1172,7 +1177,7 @@ struct ib_ucontext {
/* A list of umems that don't have private mmu notifier counters yet. */
struct list_head no_private_counters;
int odp_mrs_count;
-#endif /* !CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
+#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM */
#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
};

@@ -1657,6 +1662,14 @@ struct ib_device {

struct ib_dma_mapping_ops *dma_ops;

+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING_HMM
+ /* For ODP using HMM. */
+ struct hmm_device hmm_dev;
+ struct list_head ib_mirrors;
+ struct mutex hmm_mutex;
+ bool hmm_ready;
+#endif
+
struct module *owner;
struct device dev;
struct kobject *ports_parent;
--
1.9.3


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