sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 92 insertions, 0 deletions

diff --git a/drivers/clk/qcom/common.h b/drivers/clk/qcom/common.h
new file mode 100644
index 000000000..6f2406f88
--- /dev/null
+++ b/drivers/clk/qcom/common.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2014, The Linux Foundation. All rights reserved. */
+
+#ifndef __QCOM_CLK_COMMON_H__
+#define __QCOM_CLK_COMMON_H__
+
+struct platform_device;
+struct regmap_config;
+struct clk_regmap;
+struct qcom_reset_map;
+struct regmap;
+struct freq_tbl;
+struct clk_hw;
+
+#define PLL_LOCK_COUNT_SHIFT	8
+#define PLL_LOCK_COUNT_MASK	0x3f
+#define PLL_BIAS_COUNT_SHIFT	14
+#define PLL_BIAS_COUNT_MASK	0x3f
+#define PLL_VOTE_FSM_ENA	BIT(20)
+#define PLL_VOTE_FSM_RESET	BIT(21)
+
+struct qcom_icc_hws_data {
+	int master_id;
+	int slave_id;
+	int clk_id;
+};
+
+struct qcom_cc_driver_data {
+	struct clk_alpha_pll **alpha_plls;
+	size_t num_alpha_plls;
+	const u32 *clk_cbcrs;
+	size_t num_clk_cbcrs;
+	const struct clk_rcg_dfs_data *dfs_rcgs;
+	size_t num_dfs_rcgs;
+	void (*clk_regs_configure)(struct device *dev, struct regmap *regmap);
+};
+
+struct qcom_cc_desc {
+	const struct regmap_config *config;
+	struct clk_regmap **clks;
+	size_t num_clks;
+	const struct qcom_reset_map *resets;
+	size_t num_resets;
+	struct gdsc **gdscs;
+	size_t num_gdscs;
+	struct clk_hw **clk_hws;
+	size_t num_clk_hws;
+	const struct qcom_icc_hws_data *icc_hws;
+	size_t num_icc_hws;
+	unsigned int icc_first_node_id;
+	bool use_rpm;
+	const struct qcom_cc_driver_data *driver_data;
+};
+
+/**
+ * struct parent_map - map table for source select configuration values
+ * @src: source
+ * @cfg: configuration value
+ */
+struct parent_map {
+	u8 src;
+	u8 cfg;
+};
+
+extern const struct freq_tbl *qcom_find_freq(const struct freq_tbl *f,
+					     unsigned long rate);
+extern const struct freq_tbl *qcom_find_freq_floor(const struct freq_tbl *f,
+						   unsigned long rate);
+extern const struct freq_multi_tbl *qcom_find_freq_multi(const struct freq_multi_tbl *f,
+							 unsigned long rate);
+extern void
+qcom_pll_set_fsm_mode(struct regmap *m, u32 reg, u8 bias_count, u8 lock_count);
+extern int qcom_find_src_index(struct clk_hw *hw, const struct parent_map *map,
+			       u8 src);
+extern int qcom_find_cfg_index(struct clk_hw *hw, const struct parent_map *map,
+			       u8 cfg);
+
+extern int qcom_cc_register_board_clk(struct device *dev, const char *path,
+				      const char *name, unsigned long rate);
+extern int qcom_cc_register_sleep_clk(struct device *dev);
+
+extern struct regmap *qcom_cc_map(struct platform_device *pdev,
+				  const struct qcom_cc_desc *desc);
+extern int qcom_cc_really_probe(struct device *dev,
+				const struct qcom_cc_desc *desc,
+				struct regmap *regmap);
+extern int qcom_cc_probe(struct platform_device *pdev,
+			 const struct qcom_cc_desc *desc);
+extern int qcom_cc_probe_by_index(struct platform_device *pdev, int index,
+				  const struct qcom_cc_desc *desc);
+
+#endif