[PATCH v3 4/6] drm/i915: cgroup integration (v2)

[Matt Roper <matthew.d.roper@intel.com>]

Introduce a new DRM_IOCTL_I915_CGROUP_SETPARAM ioctl that will allow
userspace to set i915-specific parameters for individual cgroups.  i915
cgroup data will be registered and later looked up via the new
cgroup_priv infrastructure.

v2:
 - Large rebase/rewrite for new cgroup_priv interface

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/i915/Makefile      |   1 +
 drivers/gpu/drm/i915/i915_cgroup.c | 167 +++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.c    |   5 ++
 drivers/gpu/drm/i915/i915_drv.h    |  24 ++++++
 include/uapi/drm/i915_drm.h        |  12 +++
 5 files changed, 209 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/i915_cgroup.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 1bd9bc5b8c5c..5974e32834bf 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -48,6 +48,7 @@ i915-y := i915_drv.o \
 i915-$(CONFIG_COMPAT)   += i915_ioc32.o
 i915-$(CONFIG_DEBUG_FS) += i915_debugfs.o intel_pipe_crc.o
 i915-$(CONFIG_PERF_EVENTS) += i915_pmu.o
+i915-$(CONFIG_CGROUPS) += i915_cgroup.o
 
 # GEM code
 i915-y += i915_cmd_parser.o \
diff --git a/drivers/gpu/drm/i915/i915_cgroup.c b/drivers/gpu/drm/i915/i915_cgroup.c
new file mode 100644
index 000000000000..4a46cb167f53
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_cgroup.c
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * i915_cgroup.c - Linux cgroups integration for i915
+ *
+ * Copyright (C) 2018 Intel Corporation
+ */
+
+#include <linux/cgroup.h>
+
+#include "i915_drv.h"
+
+struct i915_cgroup_data {
+	struct cgroup_priv base;
+
+	struct list_head node;
+};
+
+static inline struct i915_cgroup_data *
+cgrp_to_i915(struct cgroup_priv *priv)
+{
+	return container_of(priv, struct i915_cgroup_data, base);
+}
+
+static void
+i915_cgroup_free(struct cgroup_priv *priv)
+{
+	struct cgroup *cgrp = priv->cgroup;
+	struct i915_cgroup_data *ipriv;
+
+	WARN_ON(!mutex_is_locked(&cgrp->privdata_mutex));
+
+	ipriv = cgrp_to_i915(priv);
+
+	/*
+	 * Remove private data from both cgroup's hashtable and i915's list.
+	 * If this function is being called as a result of cgroup removal
+	 * (as opposed to an i915 unload), it will have already been removed from
+	 * the hashtable, but the hash_del() call here is still safe.
+	 */
+	hash_del(&priv->hnode);
+	list_del(&ipriv->node);
+
+	kfree(ipriv);
+}
+
+void
+i915_cgroup_init(struct drm_i915_private *dev_priv)
+{
+	INIT_LIST_HEAD(&dev_priv->cgroup_list);
+}
+
+void
+i915_cgroup_shutdown(struct drm_i915_private *dev_priv)
+{
+	struct i915_cgroup_data *priv, *tmp;
+	struct cgroup *cgrp;
+
+	mutex_lock(&cgroup_mutex);
+
+	list_for_each_entry_safe(priv, tmp, &dev_priv->cgroup_list, node) {
+		cgrp = priv->base.cgroup;
+
+		mutex_lock(&cgrp->privdata_mutex);
+		i915_cgroup_free(&priv->base);
+		mutex_unlock(&cgrp->privdata_mutex);
+	}
+
+	mutex_unlock(&cgroup_mutex);
+}
+
+/*
+ * Return i915 cgroup private data, creating and registering it if one doesn't
+ * already exist for this cgroup.
+ */
+static struct i915_cgroup_data *
+get_or_create_cgroup_data(struct drm_i915_private *dev_priv,
+			  struct cgroup *cgrp)
+{
+	struct cgroup_priv *priv;
+	struct i915_cgroup_data *ipriv;
+
+	mutex_lock(&cgrp->privdata_mutex);
+
+	priv = cgroup_priv_lookup(cgrp, dev_priv);
+	if (priv) {
+		ipriv = cgrp_to_i915(priv);
+	} else {
+		ipriv = kzalloc(sizeof *ipriv, GFP_KERNEL);
+		if (!ipriv) {
+			ipriv = ERR_PTR(-ENOMEM);
+			goto out;
+		}
+
+		ipriv->base.key = dev_priv;
+		ipriv->base.free = i915_cgroup_free;
+		list_add(&ipriv->node, &dev_priv->cgroup_list);
+
+		cgroup_priv_install(cgrp, &ipriv->base);
+	}
+
+out:
+	mutex_unlock(&cgrp->privdata_mutex);
+
+	return ipriv;
+}
+
+/**
+ * i915_cgroup_setparam_ioctl - ioctl to alter i915 settings for a cgroup
+ * @dev: DRM device
+ * @data: data pointer for the ioctl
+ * @file_priv: DRM file handle for the ioctl call
+ *
+ * Allows i915-specific parameters to be set for a Linux cgroup.
+ */
+int
+i915_cgroup_setparam_ioctl(struct drm_device *dev,
+			   void *data,
+			   struct drm_file *file)
+{
+	struct drm_i915_cgroup_param *req = data;
+	struct cgroup *cgrp;
+	int ret;
+
+	/* We don't actually support any flags yet. */
+	if (req->flags) {
+		DRM_DEBUG_DRIVER("Invalid flags\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Make sure the file descriptor really is a cgroup fd and is on the
+	 * v2 hierarchy.
+	 */
+	cgrp = cgroup_get_from_fd(req->cgroup_fd);
+	if (IS_ERR(cgrp)) {
+		DRM_DEBUG_DRIVER("Invalid cgroup file descriptor\n");
+		return PTR_ERR(cgrp);
+	}
+
+	/*
+	 * Access control:  The strategy for using cgroups in a given
+	 * environment is generally determined by the system integrator
+	 * and/or OS vendor, so the specific policy about who can/can't
+	 * manipulate them tends to be domain-specific (and may vary
+	 * depending on the location in the cgroup hierarchy).  Rather than
+	 * trying to tie permission on this ioctl to a DRM-specific concepts
+	 * like DRM master, we'll allow cgroup parameters to be set by any
+	 * process that has been granted write access on the cgroup's
+	 * virtual file system (i.e., the same permissions that would
+	 * generally be needed to update the virtual files provided by
+	 * cgroup controllers).
+	 */
+	ret = cgroup_permission(req->cgroup_fd, MAY_WRITE);
+	if (ret)
+		goto out;
+
+	switch (req->param) {
+	default:
+		DRM_DEBUG_DRIVER("Invalid cgroup parameter %lld\n", req->param);
+		ret = -EINVAL;
+	}
+
+out:
+	cgroup_put(cgrp);
+
+	return ret;
+}
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index d61b51c0bf0b..a1c7bc9cd173 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1405,6 +1405,8 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	intel_runtime_pm_put(dev_priv);
 
+	i915_cgroup_init(dev_priv);
+
 	i915_welcome_messages(dev_priv);
 
 	return 0;
@@ -1431,6 +1433,8 @@ void i915_driver_unload(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct pci_dev *pdev = dev_priv->drm.pdev;
 
+	i915_cgroup_shutdown(dev_priv);
+
 	i915_driver_unregister(dev_priv);
 
 	if (i915_gem_suspend(dev_priv))
@@ -2832,6 +2836,7 @@ static const struct drm_ioctl_desc i915_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(I915_PERF_OPEN, i915_perf_open_ioctl, DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_PERF_ADD_CONFIG, i915_perf_add_config_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_PERF_REMOVE_CONFIG, i915_perf_remove_config_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_CGROUP_SETPARAM, i915_cgroup_setparam_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 };
 
 static struct drm_driver driver = {
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7eec99d7fad4..7c38142ee009 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2006,6 +2006,9 @@ struct drm_i915_private {
 
 	struct intel_ppat ppat;
 
+	/* cgroup private data */
+	struct list_head cgroup_list;
+
 	/* Kernel Modesetting */
 
 	struct intel_crtc *plane_to_crtc_mapping[I915_MAX_PIPES];
@@ -2938,6 +2941,27 @@ intel_ggtt_update_needs_vtd_wa(struct drm_i915_private *dev_priv)
 int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
 				int enable_ppgtt);
 
+/* i915_cgroup.c */
+#ifdef CONFIG_CGROUPS
+void i915_cgroup_init(struct drm_i915_private *dev_priv);
+int i915_cgroup_setparam_ioctl(struct drm_device *dev, void *data,
+			       struct drm_file *file);
+void i915_cgroup_shutdown(struct drm_i915_private *dev_priv);
+#else
+static inline int
+i915_cgroup_init(struct drm_i915_private *dev_priv)
+{
+	return 0;
+}
+static inline void i915_cgroup_shutdown(struct drm_i915_private *dev_priv) {}
+static inline int
+i915_cgroup_setparam_ioctl(struct drm_device *dev, void *data,
+			   struct drm_file *file)
+{
+	return -EINVAL;
+}
+#endif
+
 /* i915_drv.c */
 void __printf(3, 4)
 __i915_printk(struct drm_i915_private *dev_priv, const char *level,
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 29fa48e4755d..b6651b263838 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -318,6 +318,7 @@ typedef struct _drm_i915_sarea {
 #define DRM_I915_PERF_OPEN		0x36
 #define DRM_I915_PERF_ADD_CONFIG	0x37
 #define DRM_I915_PERF_REMOVE_CONFIG	0x38
+#define DRM_I915_CGROUP_SETPARAM	0x39
 
 #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)
@@ -375,6 +376,7 @@ typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_PERF_OPEN	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_OPEN, struct drm_i915_perf_open_param)
 #define DRM_IOCTL_I915_PERF_ADD_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_ADD_CONFIG, struct drm_i915_perf_oa_config)
 #define DRM_IOCTL_I915_PERF_REMOVE_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_REMOVE_CONFIG, __u64)
+#define DRM_IOCTL_I915_CGROUP_SETPARAM		DRM_IOW(DRM_COMMAND_BASE + DRM_I915_CGROUP_SETPARAM, struct drm_i915_cgroup_param)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -1615,6 +1617,16 @@ struct drm_i915_perf_oa_config {
 	__u64 flex_regs_ptr;
 };
 
+/**
+ * Structure to set i915 parameter on a cgroup.
+ */
+struct drm_i915_cgroup_param {
+	__s32 cgroup_fd;
+	__u32 flags;
+	__u64 param;
+	__s64 value;
+};
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.14.3

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