drm/amdkfd: Add procfs-style information for KFD processes

Add a folder structure to /sys/class/kfd/kfd/ called proc which contains
subfolders, each representing an active KFD process' PID, containing 1
file: pasid.

Signed-off-by: Kent Russell <[e-mail]>
Reviewed-by: Felix Kuehling <[e-mail]>
Acked-by: Christian König <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdkfd/kfd_module.c

···
 	if (err < 0)
 		goto err_create_wq;
 
+	/* Ignore the return value, so that we can continue
+	 * to init the KFD, even if procfs isn't craated
+	 */
+	kfd_procfs_init();
+
 	kfd_debugfs_init();
 
 	return 0;
···
 {
 	kfd_debugfs_fini();
 	kfd_process_destroy_wq();
+	kfd_procfs_shutdown();
 	kfd_topology_shutdown();
 	kfd_chardev_exit();
 }

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

···
 #include <linux/kfifo.h>
 #include <linux/seq_file.h>
 #include <linux/kref.h>
+#include <linux/sysfs.h>
 #include <kgd_kfd_interface.h>
 
 #include "amd_shared.h"
···
 	 * restored after an eviction
 	 */
 	unsigned long last_restore_timestamp;
+
+	/* Kobj for our procfs */
+	struct kobject *kobj;
+	struct attribute attr_pasid;
 };
 
 #define KFD_PROCESS_TABLE_SIZE 5 /* bits: 32 entries */
···
 int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj);
 
 extern struct device *kfd_device;
+
+/* KFD's procfs */
+void kfd_procfs_init(void);
+void kfd_procfs_shutdown(void);
 
 /* Topology */
 int kfd_topology_init(void);

drivers/gpu/drm/amd/amdkfd/kfd_process.c

···
 static void evict_process_worker(struct work_struct *work);
 static void restore_process_worker(struct work_struct *work);
 
+struct kfd_procfs_tree {
+	struct kobject *kobj;
+};
+
+static struct kfd_procfs_tree procfs;
+
+static ssize_t kfd_procfs_show(struct kobject *kobj, struct attribute *attr,
+			       char *buffer)
+{
+	int val = 0;
+
+	if (strcmp(attr->name, "pasid") == 0) {
+		struct kfd_process *p = container_of(attr, struct kfd_process,
+						     attr_pasid);
+		val = p->pasid;
+	} else {
+		pr_err("Invalid attribute");
+		return -EINVAL;
+	}
+
+	return snprintf(buffer, PAGE_SIZE, "%d\n", val);
+}
+
+static void kfd_procfs_kobj_release(struct kobject *kobj)
+{
+	kfree(kobj);
+}
+
+static const struct sysfs_ops kfd_procfs_ops = {
+	.show = kfd_procfs_show,
+};
+
+static struct kobj_type procfs_type = {
+	.release = kfd_procfs_kobj_release,
+	.sysfs_ops = &kfd_procfs_ops,
+};
+
+void kfd_procfs_init(void)
+{
+	int ret = 0;
+
+	procfs.kobj = kfd_alloc_struct(procfs.kobj);
+	if (!procfs.kobj)
+		return;
+
+	ret = kobject_init_and_add(procfs.kobj, &procfs_type,
+				   &kfd_device->kobj, "proc");
+	if (ret) {
+		pr_warn("Could not create procfs proc folder");
+		/* If we fail to create the procfs, clean up */
+		kfd_procfs_shutdown();
+	}
+}
+
+void kfd_procfs_shutdown(void)
+{
+	if (procfs.kobj) {
+		kobject_del(procfs.kobj);
+		kobject_put(procfs.kobj);
+		procfs.kobj = NULL;
+	}
+}
 
 int kfd_process_create_wq(void)
 {
···
 {
 	struct kfd_process *process;
 	struct task_struct *thread = current;
+	int ret;
 
 	if (!thread->mm)
 		return ERR_PTR(-EINVAL);
···
 
 	/* A prior open of /dev/kfd could have already created the process. */
 	process = find_process(thread);
-	if (process)
+	if (process) {
 		pr_debug("Process already found\n");
-	else
+	} else {
 		process = create_process(thread, filep);
 
+		if (!procfs.kobj)
+			goto out;
+
+		process->kobj = kfd_alloc_struct(process->kobj);
+		if (!process->kobj) {
+			pr_warn("Creating procfs kobject failed");
+			goto out;
+		}
+		ret = kobject_init_and_add(process->kobj, &procfs_type,
+					   procfs.kobj, "%d",
+					   (int)process->lead_thread->pid);
+		if (ret) {
+			pr_warn("Creating procfs pid directory failed");
+			goto out;
+		}
+
+		process->attr_pasid.name = "pasid";
+		process->attr_pasid.mode = KFD_SYSFS_FILE_MODE;
+		sysfs_attr_init(&process->attr_pasid);
+		ret = sysfs_create_file(process->kobj, &process->attr_pasid);
+		if (ret)
+			pr_warn("Creating pasid for pid %d failed",
+					(int)process->lead_thread->pid);
+	}
+out:
 	mutex_unlock(&kfd_processes_mutex);
 
 	return process;
···
 {
 	struct kfd_process *p = container_of(work, struct kfd_process,
 					     release_work);
+
+	/* Remove the procfs files */
+	if (p->kobj) {
+		sysfs_remove_file(p->kobj, &p->attr_pasid);
+		kobject_del(p->kobj);
+		kobject_put(p->kobj);
+		p->kobj = NULL;
+	}
 
 	kfd_iommu_unbind_process(p);