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

[Chen, Xiaogang]

On 10/30/2025 9:48 PM, Zhu, Lingshan wrote:
On 10/30/2025 11:53 PM, 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.
current sysfs implementation exposing PASID to user space, but buggy value 0, 
this commit
intends to fix this issue.

It is just for keeping current tools working. The PASID value has no 
meaning for use space that it would not get useful info about driver 
through it or uses PASID to change driver behavior.

Regards

Xiaogang


Thanks
Lingshan

Signed-off-by: Zhu Lingshan <lingshan....@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)