[PATCH v3] accel/ivpu: Limit number of maximum contexts and doorbells per user

[Maciej Falkowski <maciej.falkowski@linux.intel.com>]

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>
---
v2 -> v3:
  - Refactor to use kzalloc_obj*() due to treewide rework.
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 5900a40c7a78..dd3a486df5f1 100644
--- a/drivers/accel/ivpu/ivpu_drv.c
+++ b/drivers/accel/ivpu/ivpu_drv.c
@@ -67,6 +67,73 @@ 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_obj(*limits);
+	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;
@@ -110,6 +177,7 @@ 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);
@@ -169,7 +237,7 @@ 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;
@@ -231,22 +299,30 @@ 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_obj(*file_priv);
 	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);
@@ -284,6 +360,8 @@ 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;
@@ -343,8 +421,7 @@ 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;
 	}
 
@@ -453,7 +530,7 @@ 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,
@@ -592,6 +669,7 @@ 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;
@@ -600,6 +678,10 @@ 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;
@@ -717,7 +799,7 @@ 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 5b34b6f50e69..6378e23e0c97 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
 
@@ -123,6 +121,16 @@ 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;
@@ -142,6 +150,8 @@ 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;
@@ -189,6 +199,7 @@ 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;
@@ -286,6 +297,13 @@ 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 fe02b7bd465b..f0154dfa6ddc 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);
-- 
2.43.0