[PATCH 8/9] amdkfd: identify a secondary kfd process by its id

[Zhu Lingshan]

This commit introduces a new id field for
struct kfd process, which helps identify
a kfd process among multiple contexts that
all belong to a single user space program.

The sysfs entry of a secondary kfd process
is placed under the sysfs entry folder of
its primary kfd process.

The naming format of the sysfs entry of a secondary
kfd process is "context_%u" where %u is the process id.

Signed-off-by: Zhu Lingshan <lingshan.zhu at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  6 ++
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 82 +++++++++++++++++++++++-
 2 files changed, 85 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index de701d72aa5c..a6e12c705734 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -995,6 +995,9 @@ struct kfd_process {
 	/* Tracks debug per-vmid request for debug flags */
 	u32 dbg_flags;
 
+	/* kfd process id */
+	u16 id;
+
 	atomic_t poison;
 	/* Queues are in paused stated because we are in the process of doing a CRIU checkpoint */
 	bool queues_paused;
@@ -1009,6 +1012,9 @@ struct kfd_process {
 
 	/* indicating whether this is a primary kfd_process */
 	bool primary;
+
+	/* The primary kfd_process allocating IDs for its secondary kfd_process, 0 for primary kfd_process */
+	struct ida id_table;
 };
 
 #define KFD_PROCESS_TABLE_SIZE 8 /* bits: 256 entries */
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 440fde75d1e4..e1ba9015bb83 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -54,6 +54,9 @@ DEFINE_MUTEX(kfd_processes_mutex);
 
 DEFINE_SRCU(kfd_processes_srcu);
 
+#define KFD_PROCESS_ID_MIN 1
+#define KFD_PROCESS_ID_WIDTH 16
+
 /* For process termination handling */
 static struct workqueue_struct *kfd_process_wq;
 
@@ -827,6 +830,7 @@ static void kfd_process_device_destroy_ib_mem(struct kfd_process_device *pdd)
 
 int kfd_create_process_sysfs(struct kfd_process *process)
 {
+	struct kfd_process *primary_process;
 	int ret;
 
 	if (process->kobj) {
@@ -839,9 +843,22 @@ int kfd_create_process_sysfs(struct kfd_process *process)
 		pr_warn("Creating procfs kobject failed");
 		return -ENOMEM;
 	}
-	ret = kobject_init_and_add(process->kobj, &procfs_type,
-				   procfs.kobj, "%d",
-				   (int)process->lead_thread->pid);
+
+	if (process->primary)
+		ret = kobject_init_and_add(process->kobj, &procfs_type,
+					   procfs.kobj, "%d",
+					   (int)process->lead_thread->pid);
+	else {
+		primary_process = kfd_lookup_process_by_mm(process->lead_thread->mm);
+		if (!primary_process)
+			return -EFAULT;
+
+		ret = kobject_init_and_add(process->kobj, &procfs_type,
+					   primary_process->kobj, "context_%u",
+					   process->id);
+		kfd_unref_process(primary_process);
+	}
+
 	if (ret) {
 		pr_warn("Creating procfs pid directory failed");
 		kobject_put(process->kobj);
@@ -863,6 +880,51 @@ int kfd_create_process_sysfs(struct kfd_process *process)
 	return 0;
 }
 
+static int kfd_process_alloc_id(struct kfd_process *process)
+{
+	u16 ret;
+	struct kfd_process *primary_process;
+
+	if (process->primary) {
+		process->id = 0;
+
+		return 0;
+	}
+
+	primary_process = kfd_lookup_process_by_mm(process->lead_thread->mm);
+	if (!primary_process)
+		return -EFAULT;
+
+	ret = ida_alloc_range(&primary_process->id_table, KFD_PROCESS_ID_MIN,
+	     1 << (KFD_PROCESS_ID_WIDTH - 1), GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	process->id = ret;
+
+	kfd_unref_process(primary_process);
+
+	return 0;
+}
+
+static void kfd_process_free_id(struct kfd_process *process)
+{
+	struct kfd_process *primary_process;
+
+	if (process->primary)
+		return;
+
+	primary_process = kfd_lookup_process_by_mm(process->lead_thread->mm);
+	if (!primary_process)
+		return;
+
+	ida_free(&primary_process->id_table, process->id);
+
+	kfd_unref_process(primary_process);
+
+	return;
+}
+
 struct kfd_process *kfd_create_process(struct task_struct *thread)
 {
 	struct kfd_process *process;
@@ -1193,6 +1255,11 @@ static void kfd_process_wq_release(struct work_struct *work)
 	if (ef)
 		dma_fence_signal(ef);
 
+	if (!p->primary)
+		kfd_process_free_id(p);
+	else
+		ida_destroy(&p->id_table);
+
 	kfd_process_remove_sysfs(p);
 	kfd_debugfs_remove_process(p);
 
@@ -1549,6 +1616,12 @@ static struct kfd_process *create_process(const struct task_struct *thread, bool
 	process->queues_paused = false;
 	process->primary = primary;
 
+	err = kfd_process_alloc_id(process);
+	if (err) {
+		pr_err("Creating kfd process: failed to alloc an id\n");
+		goto err_alloc_process;
+	}
+
 	INIT_DELAYED_WORK(&process->eviction_work, evict_process_worker);
 	INIT_DELAYED_WORK(&process->restore_work, restore_process_worker);
 	process->last_restore_timestamp = get_jiffies_64();
@@ -1599,6 +1672,8 @@ static struct kfd_process *create_process(const struct task_struct *thread, bool
 			goto err_register_notifier;
 		}
 		BUG_ON(mn != &process->mmu_notifier);
+
+		ida_init(&process->id_table);
 	}
 
 	kfd_unref_process(process);
@@ -1619,6 +1694,7 @@ static struct kfd_process *create_process(const struct task_struct *thread, bool
 err_process_pqm_init:
 	kfd_event_free_process(process);
 err_event_init:
+	kfd_process_free_id(process);
 	mutex_destroy(&process->mutex);
 	kfree(process);
 err_alloc_process:
-- 
2.47.1