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, 258 insertions, 0 deletions

diff --git a/sound/soc/sof/sof-client-probes-ipc3.c b/sound/soc/sof/sof-client-probes-ipc3.c
new file mode 100644
index 000000000..a3e382d61
--- /dev/null
+++ b/sound/soc/sof/sof-client-probes-ipc3.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2019-2022 Intel Corporation
+//
+// Author: Cezary Rojewski <cezary.rojewski@intel.com>
+//
+// Code moved to this file by:
+//  Jyri Sarha <jyri.sarha@intel.com>
+//
+
+#include <linux/stddef.h>
+#include <sound/soc.h>
+#include <sound/sof/header.h>
+#include "sof-client.h"
+#include "sof-client-probes.h"
+
+struct sof_probe_dma {
+	unsigned int stream_tag;
+	unsigned int dma_buffer_size;
+} __packed;
+
+struct sof_ipc_probe_dma_add_params {
+	struct sof_ipc_cmd_hdr hdr;
+	unsigned int num_elems;
+	struct sof_probe_dma dma[];
+} __packed;
+
+struct sof_ipc_probe_info_params {
+	struct sof_ipc_reply rhdr;
+	unsigned int num_elems;
+	union {
+		DECLARE_FLEX_ARRAY(struct sof_probe_dma, dma);
+		DECLARE_FLEX_ARRAY(struct sof_probe_point_desc, desc);
+	};
+} __packed;
+
+struct sof_ipc_probe_point_add_params {
+	struct sof_ipc_cmd_hdr hdr;
+	unsigned int num_elems;
+	struct sof_probe_point_desc desc[];
+} __packed;
+
+struct sof_ipc_probe_point_remove_params {
+	struct sof_ipc_cmd_hdr hdr;
+	unsigned int num_elems;
+	unsigned int buffer_id[];
+} __packed;
+
+/**
+ * ipc3_probes_init - initialize data probing
+ * @cdev:		SOF client device
+ * @stream_tag:		Extractor stream tag
+ * @buffer_size:	DMA buffer size to set for extractor
+ *
+ * Host chooses whether extraction is supported or not by providing
+ * valid stream tag to DSP. Once specified, stream described by that
+ * tag will be tied to DSP for extraction for the entire lifetime of
+ * probe.
+ *
+ * Probing is initialized only once and each INIT request must be
+ * matched by DEINIT call.
+ */
+static int ipc3_probes_init(struct sof_client_dev *cdev, u32 stream_tag,
+			    size_t buffer_size)
+{
+	struct sof_ipc_probe_dma_add_params *msg;
+	size_t size = struct_size(msg, dma, 1);
+	int ret;
+
+	msg = kmalloc(size, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+	msg->hdr.size = size;
+	msg->hdr.cmd = SOF_IPC_GLB_PROBE | SOF_IPC_PROBE_INIT;
+	msg->num_elems = 1;
+	msg->dma[0].stream_tag = stream_tag;
+	msg->dma[0].dma_buffer_size = buffer_size;
+
+	ret = sof_client_ipc_tx_message_no_reply(cdev, msg);
+	kfree(msg);
+	return ret;
+}
+
+/**
+ * ipc3_probes_deinit - cleanup after data probing
+ * @cdev:		SOF client device
+ *
+ * Host sends DEINIT request to free previously initialized probe
+ * on DSP side once it is no longer needed. DEINIT only when there
+ * are no probes connected and with all injectors detached.
+ */
+static int ipc3_probes_deinit(struct sof_client_dev *cdev)
+{
+	struct sof_ipc_cmd_hdr msg;
+
+	msg.size = sizeof(msg);
+	msg.cmd = SOF_IPC_GLB_PROBE | SOF_IPC_PROBE_DEINIT;
+
+	return sof_client_ipc_tx_message_no_reply(cdev, &msg);
+}
+
+static int ipc3_probes_info(struct sof_client_dev *cdev, unsigned int cmd,
+			    void **params, size_t *num_params,
+			    enum sof_probe_info_type type)
+{
+	size_t max_msg_size = sof_client_get_ipc_max_payload_size(cdev);
+	struct device *dev = &cdev->auxdev.dev;
+	struct sof_ipc_probe_info_params msg = {{{0}}};
+	struct sof_ipc_probe_info_params *reply;
+	size_t bytes, elem_size, payload_size;
+	int ret;
+
+	*params = NULL;
+	*num_params = 0;
+
+	if (type != PROBES_INFO_ACTIVE_PROBES) {
+		dev_err(dev, "%s: info type %u not supported", __func__, type);
+		return -EOPNOTSUPP;
+	}
+
+	reply = kzalloc(max_msg_size, GFP_KERNEL);
+	if (!reply)
+		return -ENOMEM;
+	msg.rhdr.hdr.size = sizeof(msg);
+	msg.rhdr.hdr.cmd = SOF_IPC_GLB_PROBE | cmd;
+
+	ret = sof_client_ipc_tx_message(cdev, &msg, reply, max_msg_size);
+	if (ret < 0 || reply->rhdr.error < 0)
+		goto exit;
+
+	payload_size = reply->rhdr.hdr.size;
+	if (payload_size < offsetof(struct sof_ipc_probe_info_params, dma)) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	if (!reply->num_elems)
+		goto exit;
+
+	if (cmd == SOF_IPC_PROBE_DMA_INFO)
+		elem_size = sizeof(reply->dma[0]);
+	else
+		elem_size = sizeof(reply->desc[0]);
+
+	payload_size -= offsetof(struct sof_ipc_probe_info_params, dma);
+	if (reply->num_elems > payload_size / elem_size) {
+		dev_err(dev, "%s: invalid probe info element count %u\n",
+			__func__, reply->num_elems);
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	bytes = reply->num_elems * elem_size;
+	*params = kmemdup(&reply->dma[0], bytes, GFP_KERNEL);
+	if (!*params) {
+		ret = -ENOMEM;
+		goto exit;
+	}
+	*num_params = reply->num_elems;
+
+exit:
+	kfree(reply);
+	return ret;
+}
+
+/**
+ * ipc3_probes_points_info - retrieve list of probe points
+ * @cdev:		SOF client device
+ * @desc:	Returned list of active probes
+ * @num_desc:	Returned count of active probes
+ * @type:	Either PROBES_INFO_ACTIVE_PROBES or PROBES_INFO_AVAILABE_PROBES
+ *
+ * If type is PROBES_INFO_ACTIVE_PROBES, host sends PROBE_POINT_INFO
+ * request to obtain list of active probe points, valid for
+ * disconnection when given probe is no longer required.
+ *
+ * Type PROBES_INFO_AVAILABE_PROBES is not yet supported.
+ */
+static int ipc3_probes_points_info(struct sof_client_dev *cdev,
+				   struct sof_probe_point_desc **desc,
+				   size_t *num_desc,
+				   enum sof_probe_info_type type)
+{
+	return ipc3_probes_info(cdev, SOF_IPC_PROBE_POINT_INFO,
+				(void **)desc, num_desc, type);
+}
+
+/**
+ * ipc3_probes_points_add - connect specified probes
+ * @cdev:		SOF client device
+ * @desc:	List of probe points to connect
+ * @num_desc:	Number of elements in @desc
+ *
+ * Dynamically connects to provided set of endpoints. Immediately
+ * after connection is established, host must be prepared to
+ * transfer data from or to target stream given the probing purpose.
+ *
+ * Each probe point should be removed using PROBE_POINT_REMOVE
+ * request when no longer needed.
+ */
+static int ipc3_probes_points_add(struct sof_client_dev *cdev,
+				  struct sof_probe_point_desc *desc,
+				  size_t num_desc)
+{
+	struct sof_ipc_probe_point_add_params *msg;
+	size_t size = struct_size(msg, desc, num_desc);
+	int ret;
+
+	msg = kmalloc(size, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+	msg->hdr.size = size;
+	msg->num_elems = num_desc;
+	msg->hdr.cmd = SOF_IPC_GLB_PROBE | SOF_IPC_PROBE_POINT_ADD;
+	memcpy(&msg->desc[0], desc, size - sizeof(*msg));
+
+	ret = sof_client_ipc_tx_message_no_reply(cdev, msg);
+	kfree(msg);
+	return ret;
+}
+
+/**
+ * ipc3_probes_points_remove - disconnect specified probes
+ * @cdev:		SOF client device
+ * @buffer_id:		List of probe points to disconnect
+ * @num_buffer_id:	Number of elements in @desc
+ *
+ * Removes previously connected probes from list of active probe
+ * points and frees all resources on DSP side.
+ */
+static int ipc3_probes_points_remove(struct sof_client_dev *cdev,
+				     unsigned int *buffer_id,
+				     size_t num_buffer_id)
+{
+	struct sof_ipc_probe_point_remove_params *msg;
+	size_t size = struct_size(msg, buffer_id, num_buffer_id);
+	int ret;
+
+	msg = kmalloc(size, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+	msg->hdr.size = size;
+	msg->num_elems = num_buffer_id;
+	msg->hdr.cmd = SOF_IPC_GLB_PROBE | SOF_IPC_PROBE_POINT_REMOVE;
+	memcpy(&msg->buffer_id[0], buffer_id, size - sizeof(*msg));
+
+	ret = sof_client_ipc_tx_message_no_reply(cdev, msg);
+	kfree(msg);
+	return ret;
+}
+
+const struct sof_probes_ipc_ops ipc3_probe_ops =  {
+	.init = ipc3_probes_init,
+	.deinit = ipc3_probes_deinit,
+	.points_info = ipc3_probes_points_info,
+	.points_add = ipc3_probes_points_add,
+	.points_remove = ipc3_probes_points_remove,
+};