drm/amdkfd: Create KFD VMs on demand

Instead of creating all VMs on process creation, create them when
a process is bound to a device. This will later allow registering
an existing VM from a DRM render node FD at runtime, before the
process is bound to the device. This way the render node VM can be
used for KFD instead of creating our own redundant VM.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

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

@@ -536,6 +536,7 @@ struct kfd_process_device {
 	uint64_t scratch_limit;
 
 	/* VM context for GPUVM allocations */
+	struct file *drm_file;
 	void *vm;
 
 	/* Flag used to tell the pdd has dequeued from the dqm.
@@ -661,6 +662,8 @@ void kfd_unref_process(struct kfd_process *p);
 void kfd_suspend_all_processes(void);
 int kfd_resume_all_processes(void);
 
+int kfd_process_device_init_vm(struct kfd_process_device *pdd,
+			       struct file *drm_file);
 struct kfd_process_device *kfd_bind_process_to_device(struct kfd_dev *dev,
 						struct kfd_process *p);
 struct kfd_process_device *kfd_get_process_device_data(struct kfd_dev *dev,

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

@@ -30,6 +30,7 @@
 #include <linux/notifier.h>
 #include <linux/compat.h>
 #include <linux/mman.h>
+#include <linux/file.h>
 
 struct mm_struct;
 
@@ -158,7 +159,9 @@ static void kfd_process_destroy_pdds(struct kfd_process *p)
 		pr_debug("Releasing pdd (topology id %d) for process (pasid %d)\n",
 				pdd->dev->id, p->pasid);
 
-		if (pdd->vm)
+		if (pdd->drm_file)
+			fput(pdd->drm_file);
+		else if (pdd->vm)
 			pdd->dev->kfd2kgd->destroy_process_vm(
 				pdd->dev->kgd, pdd->vm);
 
@@ -418,18 +421,51 @@ struct kfd_process_device *kfd_create_process_device_data(struct kfd_dev *dev,
 	pdd->already_dequeued = false;
 	list_add(&pdd->per_device_list, &p->per_device_data);
 
-	/* Create the GPUVM context for this specific device */
-	if (dev->kfd2kgd->create_process_vm(dev->kgd, &pdd->vm,
-					    &p->kgd_process_info, &p->ef)) {
+	return pdd;
+}
+
+/**
+ * kfd_process_device_init_vm - Initialize a VM for a process-device
+ *
+ * @pdd: The process-device
+ * @drm_file: Optional pointer to a DRM file descriptor
+ *
+ * If @drm_file is specified, it will be used to acquire the VM from
+ * that file descriptor. If successful, the @pdd takes ownership of
+ * the file descriptor.
+ *
+ * If @drm_file is NULL, a new VM is created.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kfd_process_device_init_vm(struct kfd_process_device *pdd,
+			       struct file *drm_file)
+{
+	struct kfd_process *p;
+	struct kfd_dev *dev;
+	int ret;
+
+	if (pdd->vm)
+		return drm_file ? -EBUSY : 0;
+
+	p = pdd->process;
+	dev = pdd->dev;
+
+	if (drm_file)
+		ret = dev->kfd2kgd->acquire_process_vm(
+			dev->kgd, drm_file,
+			&pdd->vm, &p->kgd_process_info, &p->ef);
+	else
+		ret = dev->kfd2kgd->create_process_vm(
+			dev->kgd, &pdd->vm, &p->kgd_process_info, &p->ef);
+	if (ret) {
 		pr_err("Failed to create process VM object\n");
-		goto err_create_pdd;
+		return ret;
 	}
-	return pdd;
 
-err_create_pdd:
-	list_del(&pdd->per_device_list);
-	kfree(pdd);
-	return NULL;
+	pdd->drm_file = drm_file;
+
+	return 0;
 }
 
 /*
@@ -455,6 +491,10 @@ struct kfd_process_device *kfd_bind_process_to_device(struct kfd_dev *dev,
 	if (err)
 		return ERR_PTR(err);
 
+	err = kfd_process_device_init_vm(pdd, NULL);
+	if (err)
+		return ERR_PTR(err);
+
 	return pdd;
 }