Re: [PATCH v2] accel/ivpu: Limit number of maximum contexts and doorbells per user

[Lizhi Hou <lizhi.hou@amd.com>]

Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>

On 2/25/26 10:06, Maciej Falkowski wrote:
> From: Karol Wachowski <karol.wachowski@linux.intel.com>
>
> Implement per-user resource limits to prevent resource exhaustion.
>
> Root users can allocate all available contexts (128) and doorbells
> (255), while non-root users are limited to half of the available
> resources (64 contexts and 127 doorbells respectively).
>
> This prevents scenarios where a single user could monopolize NPU
> resources and starve other users on multi-user systems.
>
> Change doorbell ID and command queue ID allocation errors to debug
> messages as those are user triggered.
>
> Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
> Signed-off-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
> ---
> v1 -> v2:
>    - Fixed off-by-one error (Lizhi)
> ---
>   drivers/accel/ivpu/ivpu_drv.c | 94 ++++++++++++++++++++++++++++++++---
>   drivers/accel/ivpu/ivpu_drv.h | 26 ++++++++--
>   drivers/accel/ivpu/ivpu_job.c | 36 ++++++++++----
>   3 files changed, 136 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/accel/ivpu/ivpu_drv.c b/drivers/accel/ivpu/ivpu_drv.c
> index 3b6ec8eecf2f..1d9f7d2f71a2 100644
> --- a/drivers/accel/ivpu/ivpu_drv.c
> +++ b/drivers/accel/ivpu/ivpu_drv.c
> @@ -68,6 +68,73 @@ bool ivpu_force_snoop;
>   module_param_named(force_snoop, ivpu_force_snoop, bool, 0444);
>   MODULE_PARM_DESC(force_snoop, "Force snooping for NPU host memory access");
>   
> +static struct ivpu_user_limits *ivpu_user_limits_alloc(struct ivpu_device *vdev, uid_t uid)
> +{
> +	struct ivpu_user_limits *limits;
> +
> +	limits = kzalloc(sizeof(*limits), GFP_KERNEL);
> +	if (!limits)
> +		return ERR_PTR(-ENOMEM);
> +
> +	kref_init(&limits->ref);
> +	atomic_set(&limits->db_count, 0);
> +	limits->vdev = vdev;
> +	limits->uid = uid;
> +
> +	/* Allow root user to allocate all contexts */
> +	if (uid == 0) {
> +		limits->max_ctx_count = ivpu_get_context_count(vdev);
> +		limits->max_db_count = ivpu_get_doorbell_count(vdev);
> +	} else {
> +		limits->max_ctx_count = ivpu_get_context_count(vdev) / 2;
> +		limits->max_db_count = ivpu_get_doorbell_count(vdev) / 2;
> +	}
> +
> +	hash_add(vdev->user_limits, &limits->hash_node, uid);
> +
> +	return limits;
> +}
> +
> +static struct ivpu_user_limits *ivpu_user_limits_get(struct ivpu_device *vdev)
> +{
> +	struct ivpu_user_limits *limits;
> +	uid_t uid = current_uid().val;
> +
> +	guard(mutex)(&vdev->user_limits_lock);
> +
> +	hash_for_each_possible(vdev->user_limits, limits, hash_node, uid) {
> +		if (limits->uid == uid) {
> +			if (kref_read(&limits->ref) >= limits->max_ctx_count) {
> +				ivpu_dbg(vdev, IOCTL, "User %u exceeded max ctx count %u\n", uid,
> +					 limits->max_ctx_count);
> +				return ERR_PTR(-EMFILE);
> +			}
> +
> +			kref_get(&limits->ref);
> +			return limits;
> +		}
> +	}
> +
> +	return ivpu_user_limits_alloc(vdev, uid);
> +}
> +
> +static void ivpu_user_limits_release(struct kref *ref)
> +{
> +	struct ivpu_user_limits *limits = container_of(ref, struct ivpu_user_limits, ref);
> +	struct ivpu_device *vdev = limits->vdev;
> +
> +	lockdep_assert_held(&vdev->user_limits_lock);
> +	drm_WARN_ON(&vdev->drm, atomic_read(&limits->db_count));
> +	hash_del(&limits->hash_node);
> +	kfree(limits);
> +}
> +
> +static void ivpu_user_limits_put(struct ivpu_device *vdev, struct ivpu_user_limits *limits)
> +{
> +	guard(mutex)(&vdev->user_limits_lock);
> +	kref_put(&limits->ref, ivpu_user_limits_release);
> +}
> +
>   struct ivpu_file_priv *ivpu_file_priv_get(struct ivpu_file_priv *file_priv)
>   {
>   	struct ivpu_device *vdev = file_priv->vdev;
> @@ -111,6 +178,7 @@ static void file_priv_release(struct kref *ref)
>   	mutex_unlock(&vdev->context_list_lock);
>   	pm_runtime_put_autosuspend(vdev->drm.dev);
>   
> +	ivpu_user_limits_put(vdev, file_priv->user_limits);
>   	mutex_destroy(&file_priv->ms_lock);
>   	mutex_destroy(&file_priv->lock);
>   	kfree(file_priv);
> @@ -170,7 +238,7 @@ static int ivpu_get_param_ioctl(struct drm_device *dev, void *data, struct drm_f
>   		args->value = ivpu_hw_dpu_max_freq_get(vdev);
>   		break;
>   	case DRM_IVPU_PARAM_NUM_CONTEXTS:
> -		args->value = ivpu_get_context_count(vdev);
> +		args->value = file_priv->user_limits->max_ctx_count;
>   		break;
>   	case DRM_IVPU_PARAM_CONTEXT_BASE_ADDRESS:
>   		args->value = vdev->hw->ranges.user.start;
> @@ -232,22 +300,30 @@ static int ivpu_open(struct drm_device *dev, struct drm_file *file)
>   {
>   	struct ivpu_device *vdev = to_ivpu_device(dev);
>   	struct ivpu_file_priv *file_priv;
> +	struct ivpu_user_limits *limits;
>   	u32 ctx_id;
>   	int idx, ret;
>   
>   	if (!drm_dev_enter(dev, &idx))
>   		return -ENODEV;
>   
> +	limits = ivpu_user_limits_get(vdev);
> +	if (IS_ERR(limits)) {
> +		ret = PTR_ERR(limits);
> +		goto err_dev_exit;
> +	}
> +
>   	file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
>   	if (!file_priv) {
>   		ret = -ENOMEM;
> -		goto err_dev_exit;
> +		goto err_user_limits_put;
>   	}
>   
>   	INIT_LIST_HEAD(&file_priv->ms_instance_list);
>   
>   	file_priv->vdev = vdev;
>   	file_priv->bound = true;
> +	file_priv->user_limits = limits;
>   	kref_init(&file_priv->ref);
>   	mutex_init(&file_priv->lock);
>   	mutex_init(&file_priv->ms_lock);
> @@ -285,6 +361,8 @@ static int ivpu_open(struct drm_device *dev, struct drm_file *file)
>   	mutex_destroy(&file_priv->ms_lock);
>   	mutex_destroy(&file_priv->lock);
>   	kfree(file_priv);
> +err_user_limits_put:
> +	ivpu_user_limits_put(vdev, limits);
>   err_dev_exit:
>   	drm_dev_exit(idx);
>   	return ret;
> @@ -344,8 +422,7 @@ static int ivpu_wait_for_ready(struct ivpu_device *vdev)
>   	ivpu_ipc_consumer_del(vdev, &cons);
>   
>   	if (!ret && ipc_hdr.data_addr != IVPU_IPC_BOOT_MSG_DATA_ADDR) {
> -		ivpu_err(vdev, "Invalid NPU ready message: 0x%x\n",
> -			 ipc_hdr.data_addr);
> +		ivpu_err(vdev, "Invalid NPU ready message: 0x%x\n", ipc_hdr.data_addr);
>   		return -EIO;
>   	}
>   
> @@ -454,7 +531,7 @@ int ivpu_shutdown(struct ivpu_device *vdev)
>   }
>   
>   static const struct file_operations ivpu_fops = {
> -	.owner		= THIS_MODULE,
> +	.owner = THIS_MODULE,
>   	DRM_ACCEL_FOPS,
>   #ifdef CONFIG_PROC_FS
>   	.show_fdinfo = drm_show_fdinfo,
> @@ -593,6 +670,7 @@ static int ivpu_dev_init(struct ivpu_device *vdev)
>   	xa_init_flags(&vdev->submitted_jobs_xa, XA_FLAGS_ALLOC1);
>   	xa_init_flags(&vdev->db_xa, XA_FLAGS_ALLOC1);
>   	INIT_LIST_HEAD(&vdev->bo_list);
> +	hash_init(vdev->user_limits);
>   
>   	vdev->db_limit.min = IVPU_MIN_DB;
>   	vdev->db_limit.max = IVPU_MAX_DB;
> @@ -601,6 +679,10 @@ static int ivpu_dev_init(struct ivpu_device *vdev)
>   	if (ret)
>   		goto err_xa_destroy;
>   
> +	ret = drmm_mutex_init(&vdev->drm, &vdev->user_limits_lock);
> +	if (ret)
> +		goto err_xa_destroy;
> +
>   	ret = drmm_mutex_init(&vdev->drm, &vdev->submitted_jobs_lock);
>   	if (ret)
>   		goto err_xa_destroy;
> @@ -718,7 +800,7 @@ static struct pci_device_id ivpu_pci_ids[] = {
>   	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_PTL_P) },
>   	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_WCL) },
>   	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_NVL) },
> -	{ }
> +	{}
>   };
>   MODULE_DEVICE_TABLE(pci, ivpu_pci_ids);
>   
> diff --git a/drivers/accel/ivpu/ivpu_drv.h b/drivers/accel/ivpu/ivpu_drv.h
> index 78ecddf2831d..0b5aa41151c6 100644
> --- a/drivers/accel/ivpu/ivpu_drv.h
> +++ b/drivers/accel/ivpu/ivpu_drv.h
> @@ -12,6 +12,7 @@
>   #include <drm/drm_mm.h>
>   #include <drm/drm_print.h>
>   
> +#include <linux/hashtable.h>
>   #include <linux/pci.h>
>   #include <linux/xarray.h>
>   #include <uapi/drm/ivpu_accel.h>
> @@ -43,7 +44,7 @@
>   /* SSID 1 is used by the VPU to represent reserved context */
>   #define IVPU_RESERVED_CONTEXT_MMU_SSID 1
>   #define IVPU_USER_CONTEXT_MIN_SSID     2
> -#define IVPU_USER_CONTEXT_MAX_SSID     (IVPU_USER_CONTEXT_MIN_SSID + 63)
> +#define IVPU_USER_CONTEXT_MAX_SSID     (IVPU_USER_CONTEXT_MIN_SSID + 128)
>   
>   #define IVPU_MIN_DB 1
>   #define IVPU_MAX_DB 255
> @@ -51,9 +52,6 @@
>   #define IVPU_JOB_ID_JOB_MASK		GENMASK(7, 0)
>   #define IVPU_JOB_ID_CONTEXT_MASK	GENMASK(31, 8)
>   
> -#define IVPU_NUM_PRIORITIES    4
> -#define IVPU_NUM_CMDQS_PER_CTX (IVPU_NUM_PRIORITIES)
> -
>   #define IVPU_CMDQ_MIN_ID 1
>   #define IVPU_CMDQ_MAX_ID 255
>   
> @@ -124,6 +122,16 @@ struct ivpu_fw_info;
>   struct ivpu_ipc_info;
>   struct ivpu_pm_info;
>   
> +struct ivpu_user_limits {
> +	struct hlist_node hash_node;
> +	struct ivpu_device *vdev;
> +	struct kref ref;
> +	u32 max_ctx_count;
> +	u32 max_db_count;
> +	u32 uid;
> +	atomic_t db_count;
> +};
> +
>   struct ivpu_device {
>   	struct drm_device drm;
>   	void __iomem *regb;
> @@ -143,6 +151,8 @@ struct ivpu_device {
>   	struct mutex context_list_lock; /* Protects user context addition/removal */
>   	struct xarray context_xa;
>   	struct xa_limit context_xa_limit;
> +	DECLARE_HASHTABLE(user_limits, 8);
> +	struct mutex user_limits_lock; /* Protects user_limits */
>   
>   	struct xarray db_xa;
>   	struct xa_limit db_limit;
> @@ -190,6 +200,7 @@ struct ivpu_file_priv {
>   	struct list_head ms_instance_list;
>   	struct ivpu_bo *ms_info_bo;
>   	struct xa_limit job_limit;
> +	struct ivpu_user_limits *user_limits;
>   	u32 job_id_next;
>   	struct xa_limit cmdq_limit;
>   	u32 cmdq_id_next;
> @@ -287,6 +298,13 @@ static inline u32 ivpu_get_context_count(struct ivpu_device *vdev)
>   	return (ctx_limit.max - ctx_limit.min + 1);
>   }
>   
> +static inline u32 ivpu_get_doorbell_count(struct ivpu_device *vdev)
> +{
> +	struct xa_limit db_limit = vdev->db_limit;
> +
> +	return (db_limit.max - db_limit.min + 1);
> +}
> +
>   static inline u32 ivpu_get_platform(struct ivpu_device *vdev)
>   {
>   	WARN_ON_ONCE(vdev->platform == IVPU_PLATFORM_INVALID);
> diff --git a/drivers/accel/ivpu/ivpu_job.c b/drivers/accel/ivpu/ivpu_job.c
> index 4f8564e2878a..337ed269fd3e 100644
> --- a/drivers/accel/ivpu/ivpu_job.c
> +++ b/drivers/accel/ivpu/ivpu_job.c
> @@ -173,7 +173,7 @@ static struct ivpu_cmdq *ivpu_cmdq_create(struct ivpu_file_priv *file_priv, u8 p
>   	ret = xa_alloc_cyclic(&file_priv->cmdq_xa, &cmdq->id, cmdq, file_priv->cmdq_limit,
>   			      &file_priv->cmdq_id_next, GFP_KERNEL);
>   	if (ret < 0) {
> -		ivpu_err(vdev, "Failed to allocate command queue ID: %d\n", ret);
> +		ivpu_dbg(vdev, IOCTL, "Failed to allocate command queue ID: %d\n", ret);
>   		goto err_free_cmdq;
>   	}
>   
> @@ -215,14 +215,22 @@ static int ivpu_hws_cmdq_init(struct ivpu_file_priv *file_priv, struct ivpu_cmdq
>   
>   static int ivpu_register_db(struct ivpu_file_priv *file_priv, struct ivpu_cmdq *cmdq)
>   {
> +	struct ivpu_user_limits *limits = file_priv->user_limits;
>   	struct ivpu_device *vdev = file_priv->vdev;
>   	int ret;
>   
> +	if (atomic_inc_return(&limits->db_count) > limits->max_db_count) {
> +		ivpu_dbg(vdev, IOCTL, "Maximum number of %u doorbells for uid %u reached\n",
> +			 limits->max_db_count, limits->uid);
> +		ret = -EBUSY;
> +		goto err_dec_db_count;
> +	}
> +
>   	ret = xa_alloc_cyclic(&vdev->db_xa, &cmdq->db_id, NULL, vdev->db_limit, &vdev->db_next,
>   			      GFP_KERNEL);
>   	if (ret < 0) {
> -		ivpu_err(vdev, "Failed to allocate doorbell ID: %d\n", ret);
> -		return ret;
> +		ivpu_dbg(vdev, IOCTL, "Failed to allocate doorbell ID: %d\n", ret);
> +		goto err_dec_db_count;
>   	}
>   
>   	if (vdev->fw->sched_mode == VPU_SCHEDULING_MODE_HW)
> @@ -231,15 +239,18 @@ static int ivpu_register_db(struct ivpu_file_priv *file_priv, struct ivpu_cmdq *
>   	else
>   		ret = ivpu_jsm_register_db(vdev, file_priv->ctx.id, cmdq->db_id,
>   					   cmdq->mem->vpu_addr, ivpu_bo_size(cmdq->mem));
> -
> -	if (!ret) {
> -		ivpu_dbg(vdev, JOB, "DB %d registered to cmdq %d ctx %d priority %d\n",
> -			 cmdq->db_id, cmdq->id, file_priv->ctx.id, cmdq->priority);
> -	} else {
> +	if (ret) {
>   		xa_erase(&vdev->db_xa, cmdq->db_id);
>   		cmdq->db_id = 0;
> +		goto err_dec_db_count;
>   	}
>   
> +	ivpu_dbg(vdev, JOB, "DB %d registered to cmdq %d ctx %d priority %d\n",
> +		 cmdq->db_id, cmdq->id, file_priv->ctx.id, cmdq->priority);
> +	return 0;
> +
> +err_dec_db_count:
> +	atomic_dec(&limits->db_count);
>   	return ret;
>   }
>   
> @@ -298,6 +309,7 @@ static int ivpu_cmdq_unregister(struct ivpu_file_priv *file_priv, struct ivpu_cm
>   	}
>   
>   	xa_erase(&file_priv->vdev->db_xa, cmdq->db_id);
> +	atomic_dec(&file_priv->user_limits->db_count);
>   	cmdq->db_id = 0;
>   
>   	return 0;
> @@ -313,6 +325,7 @@ static inline u8 ivpu_job_to_jsm_priority(u8 priority)
>   
>   static void ivpu_cmdq_destroy(struct ivpu_file_priv *file_priv, struct ivpu_cmdq *cmdq)
>   {
> +	lockdep_assert_held(&file_priv->lock);
>   	ivpu_cmdq_unregister(file_priv, cmdq);
>   	xa_erase(&file_priv->cmdq_xa, cmdq->id);
>   	ivpu_cmdq_free(file_priv, cmdq);
> @@ -380,8 +393,11 @@ static void ivpu_cmdq_reset(struct ivpu_file_priv *file_priv)
>   	mutex_lock(&file_priv->lock);
>   
>   	xa_for_each(&file_priv->cmdq_xa, cmdq_id, cmdq) {
> -		xa_erase(&file_priv->vdev->db_xa, cmdq->db_id);
> -		cmdq->db_id = 0;
> +		if (cmdq->db_id) {
> +			xa_erase(&file_priv->vdev->db_xa, cmdq->db_id);
> +			atomic_dec(&file_priv->user_limits->db_count);
> +			cmdq->db_id = 0;
> +		}
>   	}
>   
>   	mutex_unlock(&file_priv->lock);