[PATCH V6 08/18] amdkfd: identify a secondary kfd process by its id

[Zhu Lingshan <lingshan.zhu@amd.com>]

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@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  5 ++
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 78 +++++++++++++++++++++++-
 2 files changed, 80 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 919510f18249..30b0b45bcc8d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -1021,10 +1021,15 @@ struct kfd_process {
 
 	/*kfd context id */
 	u16 context_id;
+
+	/* 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 */
 #define KFD_CONTEXT_ID_PRIMARY	0xFFFF
+#define KFD_CONTEXT_ID_MIN 0
 
 extern DECLARE_HASHTABLE(kfd_processes_table, KFD_PROCESS_TABLE_SIZE);
 extern struct srcu_struct kfd_processes_srcu;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 995d27be06e3..f1e8ce61290b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -827,6 +827,7 @@ 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 +840,22 @@ 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->context_id == KFD_CONTEXT_ID_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 -ESRCH;
+
+		ret = kobject_init_and_add(process->kobj, &procfs_type,
+					   primary_process->kobj, "context_%u",
+					   process->context_id);
+		kfd_unref_process(primary_process);
+	}
+
 	if (ret) {
 		pr_warn("Creating procfs pid directory failed");
 		kobject_put(process->kobj);
@@ -863,6 +877,50 @@ int kfd_create_process_sysfs(struct kfd_process *process)
 	return 0;
 }
 
+static int kfd_process_alloc_id(struct kfd_process *process)
+{
+	int ret;
+	struct kfd_process *primary_process;
+
+	/* already assign 0xFFFF when create */
+	if (process->context_id == KFD_CONTEXT_ID_PRIMARY)
+		return 0;
+
+	primary_process = kfd_lookup_process_by_mm(process->lead_thread->mm);
+	if (!primary_process)
+		return -ESRCH;
+
+	/* id range: KFD_CONTEXT_ID_MIN to 0xFFFE */
+	ret = ida_alloc_range(&primary_process->id_table, KFD_CONTEXT_ID_MIN,
+	      KFD_CONTEXT_ID_PRIMARY - 1, GFP_KERNEL);
+	if (ret < 0)
+		goto out;
+
+	process->context_id = ret;
+	ret = 0;
+
+out:
+	kfd_unref_process(primary_process);
+
+	return ret;
+}
+
+static void kfd_process_free_id(struct kfd_process *process)
+{
+	struct kfd_process *primary_process;
+
+	if (process->context_id != KFD_CONTEXT_ID_PRIMARY)
+		return;
+
+	primary_process = kfd_lookup_process_by_mm(process->lead_thread->mm);
+	if (!primary_process)
+		return;
+
+	ida_free(&primary_process->id_table, process->context_id);
+
+	kfd_unref_process(primary_process);
+}
+
 struct kfd_process *kfd_create_process(struct task_struct *thread)
 {
 	struct kfd_process *process;
@@ -1195,6 +1253,11 @@ static void kfd_process_wq_release(struct work_struct *work)
 	if (ef)
 		dma_fence_signal(ef);
 
+	if (p->context_id != KFD_CONTEXT_ID_PRIMARY)
+		kfd_process_free_id(p);
+	else
+		ida_destroy(&p->id_table);
+
 	kfd_process_remove_sysfs(p);
 	kfd_debugfs_remove_process(p);
 
@@ -1601,6 +1664,13 @@ 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);
+	}
+
+	err = kfd_process_alloc_id(process);
+	if (err) {
+		pr_err("Creating kfd process: failed to alloc an id\n");
+		goto err_alloc_id;
 	}
 
 	kfd_unref_process(process);
@@ -1610,6 +1680,8 @@ static struct kfd_process *create_process(const struct task_struct *thread, bool
 
 	return process;
 
+err_alloc_id:
+	kfd_process_free_id(process);
 err_register_notifier:
 	hash_del_rcu(&process->kfd_processes);
 	svm_range_list_fini(process);
-- 
2.51.0