drm/i915: Add ioctl to set per-context parameters

Sometimes we wish to tweak how an individual context behaves. Since we
always create a context for every filp, this means that individual
processes can fine tune their behaviour even if they do not explicitly
create a context.

The first example parameter here is to enable multi-process GPU testing,
but the interface should be able to cope with passing arbitrarily complex
parameters.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Testcase: igt/gem_reset_stats/ban-period-*
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1066,6 +1066,8 @@ const struct drm_ioctl_desc i915_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(I915_REG_READ, i915_reg_read_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_GET_RESET_STATS, i915_get_reset_stats_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_GEM_USERPTR, i915_gem_userptr_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_GETPARAM, i915_gem_context_getparam_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_SETPARAM, i915_gem_context_setparam_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 };
 
 int i915_max_ioctl = ARRAY_SIZE(i915_ioctls);

drivers/gpu/drm/i915/i915_drv.h

@@ -2898,6 +2898,10 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 				  struct drm_file *file);
 int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
 				   struct drm_file *file);
+int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
+				    struct drm_file *file_priv);
+int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
+				    struct drm_file *file_priv);
 
 /* i915_gem_evict.c */
 int __must_check i915_gem_evict_something(struct drm_device *dev,

drivers/gpu/drm/i915/i915_gem_context.c

@@ -762,3 +762,72 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
 	DRM_DEBUG_DRIVER("HW context %d destroyed\n", args->ctx_id);
 	return 0;
 }
+
+int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
+				    struct drm_file *file)
+{
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct drm_i915_gem_context_param *args = data;
+	struct intel_context *ctx;
+	int ret;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+
+	ctx = i915_gem_context_get(file_priv, args->ctx_id);
+	if (IS_ERR(ctx)) {
+		mutex_unlock(&dev->struct_mutex);
+		return PTR_ERR(ctx);
+	}
+
+	args->size = 0;
+	switch (args->param) {
+	case I915_CONTEXT_PARAM_BAN_PERIOD:
+		args->value = ctx->hang_stats.ban_period_seconds;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&dev->struct_mutex);
+
+	return ret;
+}
+
+int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
+				    struct drm_file *file)
+{
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct drm_i915_gem_context_param *args = data;
+	struct intel_context *ctx;
+	int ret;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+
+	ctx = i915_gem_context_get(file_priv, args->ctx_id);
+	if (IS_ERR(ctx)) {
+		mutex_unlock(&dev->struct_mutex);
+		return PTR_ERR(ctx);
+	}
+
+	switch (args->param) {
+	case I915_CONTEXT_PARAM_BAN_PERIOD:
+		if (args->size)
+			ret = -EINVAL;
+		else if (args->value < ctx->hang_stats.ban_period_seconds &&
+			 !capable(CAP_SYS_ADMIN))
+			ret = -EPERM;
+		else
+			ctx->hang_stats.ban_period_seconds = args->value;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&dev->struct_mutex);
+
+	return ret;
+}

include/uapi/drm/i915_drm.h

@@ -224,6 +224,8 @@ typedef struct _drm_i915_sarea {
 #define DRM_I915_REG_READ		0x31
 #define DRM_I915_GET_RESET_STATS	0x32
 #define DRM_I915_GEM_USERPTR		0x33
+#define DRM_I915_GEM_CONTEXT_GETPARAM	0x34
+#define DRM_I915_GEM_CONTEXT_SETPARAM	0x35
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -275,6 +277,8 @@ typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_REG_READ			DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_REG_READ, struct drm_i915_reg_read)
 #define DRM_IOCTL_I915_GET_RESET_STATS		DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GET_RESET_STATS, struct drm_i915_reset_stats)
 #define DRM_IOCTL_I915_GEM_USERPTR			DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_USERPTR, struct drm_i915_gem_userptr)
+#define DRM_IOCTL_I915_GEM_CONTEXT_GETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_GETPARAM, struct drm_i915_gem_context_param)
+#define DRM_IOCTL_I915_GEM_CONTEXT_SETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_SETPARAM, struct drm_i915_gem_context_param)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -1082,4 +1086,12 @@ struct drm_i915_gem_userptr {
 	__u32 handle;
 };
 
+struct drm_i915_gem_context_param {
+	__u32 ctx_id;
+	__u32 size;
+	__u64 param;
+#define I915_CONTEXT_PARAM_BAN_PERIOD 0x1
+	__u64 value;
+};
+
 #endif /* _UAPI_I915_DRM_H_ */