Re: [PATCH] amdkfd: implement per process/device pasid in sysfs

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

On 10/30/25 16:53, Chen, Xiaogang wrote:
> 
> On 10/29/2025 10:45 PM, Zhu Lingshan wrote:
>> The pasid is a per-process-per-device attribute,
>> therefore this commit implements per
>> struct kfd_process_device->pasid in sysfs
> This per device pasid is used internally in kfd, not used at user space. So no need to exposing it.

Agree completely, the PASID is a technical attribute we use internally in the kernel and should not expose to userspace at all.

Maybe in debugfs to narrow down problems, but certainly not in sysfs. That would make the internal handling an uAPI and so not changeable any more.

Regards,
Christian.

>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  9 ++-------
>>   drivers/gpu/drm/amd/amdkfd/kfd_process.c | 18 +++++++++++-------
>>   2 files changed, 13 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
>> index 70ef051511bb..6a3cfeccacd8 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
>> @@ -864,6 +864,8 @@ struct kfd_process_device {
>>       bool has_reset_queue;
>>         u32 pasid;
>> +    char pasid_filename[MAX_SYSFS_FILENAME_LEN];
>> +    struct attribute attr_pasid;
>>   };
>>     #define qpd_to_pdd(x) container_of(x, struct kfd_process_device, qpd)
>> @@ -983,7 +985,6 @@ struct kfd_process {
>>       /* Kobj for our procfs */
>>       struct kobject *kobj;
>>       struct kobject *kobj_queues;
>> -    struct attribute attr_pasid;
> We keep it to have use space tools(ex rocm-smi) work as the tools still read it before they change.
>>         /* Keep track cwsr init */
>>       bool has_cwsr;
>> @@ -1100,12 +1101,6 @@ void kfd_process_device_remove_obj_handle(struct kfd_process_device *pdd,
>>                       int handle);
>>   struct kfd_process *kfd_lookup_process_by_pid(struct pid *pid);
>>   -/* PASIDs */
>> -int kfd_pasid_init(void);
>> -void kfd_pasid_exit(void);
>> -u32 kfd_pasid_alloc(void);
>> -void kfd_pasid_free(u32 pasid);
> This part is right, these declarations were forgotten to remove.
>> -
>>   /* Doorbells */
>>   size_t kfd_doorbell_process_slice(struct kfd_dev *kfd);
>>   int kfd_doorbell_init(struct kfd_dev *kfd);
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> index ddfe30c13e9d..24cf3b250b37 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> @@ -328,9 +328,11 @@ static int kfd_get_cu_occupancy(struct attribute *attr, char *buffer)
>>   static ssize_t kfd_procfs_show(struct kobject *kobj, struct attribute *attr,
>>                      char *buffer)
>>   {
>> -    if (strcmp(attr->name, "pasid") == 0)
>> -        return snprintf(buffer, PAGE_SIZE, "%d\n", 0);
> 
> Same as above we keep it to have compatibility with current tools.
> 
>  Regards
> 
> Xiaogang
> 
>> -    else if (strncmp(attr->name, "vram_", 5) == 0) {
>> +    if (strncmp(attr->name, "pasid_", 6) == 0) {
>> +        struct kfd_process_device *pdd = container_of(attr, struct kfd_process_device,
>> +                                  attr_pasid);
>> +        return snprintf(buffer, PAGE_SIZE, "%u\n", pdd->pasid);
>> +    } else if (strncmp(attr->name, "vram_", 5) == 0) {
>>           struct kfd_process_device *pdd = container_of(attr, struct kfd_process_device,
>>                                     attr_vram);
>>           return snprintf(buffer, PAGE_SIZE, "%llu\n", atomic64_read(&pdd->vram_usage));
>> @@ -662,6 +664,7 @@ static void kfd_procfs_add_sysfs_files(struct kfd_process *p)
>>        * Create sysfs files for each GPU:
>>        * - proc/<pid>/vram_<gpuid>
>>        * - proc/<pid>/sdma_<gpuid>
>> +     * - proc/<pid>/pasid_<gpuid>
>>        */
>>       for (i = 0; i < p->n_pdds; i++) {
>>           struct kfd_process_device *pdd = p->pdds[i];
>> @@ -675,6 +678,10 @@ static void kfd_procfs_add_sysfs_files(struct kfd_process *p)
>>                pdd->dev->id);
>>           kfd_sysfs_create_file(p->kobj, &pdd->attr_sdma,
>>                           pdd->sdma_filename);
>> +
>> +        snprintf(pdd->pasid_filename, MAX_SYSFS_FILENAME_LEN, "pasid_%u",
>> +             pdd->dev->id);
>> +        kfd_sysfs_create_file(p->kobj, &pdd->attr_pasid, pdd->pasid_filename);
>>       }
>>   }
>>   @@ -888,9 +895,6 @@ struct kfd_process *kfd_create_process(struct task_struct *thread)
>>               goto out;
>>           }
>>   -        kfd_sysfs_create_file(process->kobj, &process->attr_pasid,
>> -                      "pasid");
>> -
>>           process->kobj_queues = kobject_create_and_add("queues",
>>                               process->kobj);
>>           if (!process->kobj_queues)
>> @@ -1104,7 +1108,6 @@ static void kfd_process_remove_sysfs(struct kfd_process *p)
>>       if (!p->kobj)
>>           return;
>>   -    sysfs_remove_file(p->kobj, &p->attr_pasid);
>>       kobject_del(p->kobj_queues);
>>       kobject_put(p->kobj_queues);
>>       p->kobj_queues = NULL;
>> @@ -1114,6 +1117,7 @@ static void kfd_process_remove_sysfs(struct kfd_process *p)
>>             sysfs_remove_file(p->kobj, &pdd->attr_vram);
>>           sysfs_remove_file(p->kobj, &pdd->attr_sdma);
>> +        sysfs_remove_file(p->kobj, &pdd->attr_pasid);
>>             sysfs_remove_file(pdd->kobj_stats, &pdd->attr_evict);
>>           if (pdd->dev->kfd2kgd->get_cu_occupancy)