[PATCH] drm/amdkfd: add pasid debugfs entries

[Chen, Xiaogang]

On 4/24/2025 3:04 PM, Eric Huang wrote:
> the entries will be appearing at
> /sys/kernel/debug/kfd/proc/<pid>/pasid_<gpuid>.

why need move pasid from sysfs to debugfs? debugfs is not always 
available and does not hide pasid from users either.

Regards

Xiaogang

>
> Signed-off-by: Eric Huang <jinhuieric.huang at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c | 77 ++++++++++++++++++++++++
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  5 ++
>   drivers/gpu/drm/amd/amdkfd/kfd_process.c |  3 +
>   3 files changed, 85 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> index 4a5a0a4e00f2..14ab770fb877 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> @@ -27,6 +27,16 @@
>   #include "kfd_priv.h"
>   
>   static struct dentry *debugfs_root;
> +static struct dentry *debugfs_proc;
> +static struct list_head procs;
> +
> +struct debugfs_proc_entry {
> +	struct list_head list;
> +	struct dentry *proc_dentry;
> +	pid_t pid;
> +};
> +
> +#define MAX_DEBUGFS_FILENAME_LEN 32
>   
>   static int kfd_debugfs_open(struct inode *inode, struct file *file)
>   {
> @@ -92,6 +102,8 @@ static const struct file_operations kfd_debugfs_hang_hws_fops = {
>   void kfd_debugfs_init(void)
>   {
>   	debugfs_root = debugfs_create_dir("kfd", NULL);
> +	debugfs_proc = debugfs_create_dir("proc", debugfs_root);
> +	INIT_LIST_HEAD(&procs);
>   
>   	debugfs_create_file("mqds", S_IFREG | 0444, debugfs_root,
>   			    kfd_debugfs_mqds_by_process, &kfd_debugfs_fops);
> @@ -107,5 +119,70 @@ void kfd_debugfs_init(void)
>   
>   void kfd_debugfs_fini(void)
>   {
> +	debugfs_remove_recursive(debugfs_proc);
>   	debugfs_remove_recursive(debugfs_root);
>   }
> +
> +static ssize_t kfd_debugfs_pasid_read(struct file *file, char __user *buf,
> +				      size_t count, loff_t *ppos)
> +{
> +    struct kfd_process_device *pdd = file_inode(file)->i_private;
> +    char tmp[32];
> +    int len;
> +
> +    len = snprintf(tmp, sizeof(tmp), "%u\n", pdd->pasid);
> +
> +    return simple_read_from_buffer(buf, count, ppos, tmp, len);
> +}
> +
> +static const struct file_operations kfd_debugfs_pasid_fops = {
> +    .owner = THIS_MODULE,
> +    .read = kfd_debugfs_pasid_read,
> +};
> +
> +void kfd_debugfs_add_process(struct kfd_process *p)
> +{
> +	int i;
> +	char name[MAX_DEBUGFS_FILENAME_LEN];
> +	struct debugfs_proc_entry *entry;
> +
> +	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> +	if (!entry)
> +		return;
> +
> +	list_add(&entry->list, &procs);
> +	entry->pid = p->lead_thread->pid;
> +	snprintf(name, MAX_DEBUGFS_FILENAME_LEN, "%d",
> +		 (int)entry->pid);
> +	entry->proc_dentry = debugfs_create_dir(name, debugfs_proc);
> +
> +	/* Create debugfs files for each GPU:
> +	 * - proc/<pid>/pasid_<gpuid>
> +	 */
> +	for (i = 0; i < p->n_pdds; i++) {
> +		struct kfd_process_device *pdd = p->pdds[i];
> +
> +		snprintf(name, MAX_DEBUGFS_FILENAME_LEN, "pasid_%u",
> +			 pdd->dev->id);
> +		debugfs_create_file((const char *)name, S_IFREG | 0444,
> +				    entry->proc_dentry,
> +				    pdd,
> +				    &kfd_debugfs_pasid_fops);
> +	}
> +}
> +
> +void kfd_debugfs_remove_process(struct kfd_process *p)
> +{
> +	struct debugfs_proc_entry *entry, *next;
> +
> +	mutex_lock(&kfd_processes_mutex);
> +	list_for_each_entry_safe(entry, next, &procs, list) {
> +		if (entry->pid != p->lead_thread->pid)
> +			continue;
> +
> +		debugfs_remove_recursive(entry->proc_dentry);
> +		list_del(&entry->list);
> +		kfree(entry);
> +	}
> +	mutex_unlock(&kfd_processes_mutex);
> +}
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> index f6aedf69c644..0ae794539bb0 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> @@ -1581,10 +1581,15 @@ int kfd_debugfs_hang_hws(struct kfd_node *dev);
>   int pm_debugfs_hang_hws(struct packet_manager *pm);
>   int dqm_debugfs_hang_hws(struct device_queue_manager *dqm);
>   
> +void kfd_debugfs_add_process(struct kfd_process *p);
> +void kfd_debugfs_remove_process(struct kfd_process *p);
> +
>   #else
>   
>   static inline void kfd_debugfs_init(void) {}
>   static inline void kfd_debugfs_fini(void) {}
> +static inline void kfd_debugfs_add_process(struct kfd_process *p) {}
> +static inline void kfd_debugfs_remove_process(struct kfd_process *p) {}
>   
>   #endif
>   
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 41d7dc8c2850..722ac1662bdc 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -900,6 +900,8 @@ struct kfd_process *kfd_create_process(struct task_struct *thread)
>   		kfd_procfs_add_sysfs_files(process);
>   		kfd_procfs_add_sysfs_counters(process);
>   
> +		kfd_debugfs_add_process(process);
> +
>   		init_waitqueue_head(&process->wait_irq_drain);
>   	}
>   out:
> @@ -1176,6 +1178,7 @@ static void kfd_process_wq_release(struct work_struct *work)
>   		dma_fence_signal(ef);
>   
>   	kfd_process_remove_sysfs(p);
> +	kfd_debugfs_remove_process(p);
>   
>   	kfd_process_kunmap_signal_bo(p);
>   	kfd_process_free_outstanding_kfd_bos(p);