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, 106 insertions, 0 deletions

diff --git a/include/crypto/engine.h b/include/crypto/engine.h
new file mode 100644
index 000000000..2e6034443
--- /dev/null
+++ b/include/crypto/engine.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Crypto engine API
+ *
+ * Copyright (c) 2016 Baolin Wang <baolin.wang@linaro.org>
+ */
+#ifndef _CRYPTO_ENGINE_H
+#define _CRYPTO_ENGINE_H
+
+#include <crypto/aead.h>
+#include <crypto/akcipher.h>
+#include <crypto/hash.h>
+#include <crypto/kpp.h>
+#include <crypto/skcipher.h>
+#include <linux/types.h>
+
+struct crypto_engine;
+struct device;
+
+/*
+ * struct crypto_engine_op - crypto hardware engine operations
+ * @do_one_request: do encryption for current request
+ */
+struct crypto_engine_op {
+	int (*do_one_request)(struct crypto_engine *engine,
+			      void *areq);
+};
+
+struct aead_engine_alg {
+	struct aead_alg base;
+	struct crypto_engine_op op;
+};
+
+struct ahash_engine_alg {
+	struct ahash_alg base;
+	struct crypto_engine_op op;
+};
+
+struct akcipher_engine_alg {
+	struct akcipher_alg base;
+	struct crypto_engine_op op;
+};
+
+struct kpp_engine_alg {
+	struct kpp_alg base;
+	struct crypto_engine_op op;
+};
+
+struct skcipher_engine_alg {
+	struct skcipher_alg base;
+	struct crypto_engine_op op;
+};
+
+int crypto_transfer_aead_request_to_engine(struct crypto_engine *engine,
+					   struct aead_request *req);
+int crypto_transfer_akcipher_request_to_engine(struct crypto_engine *engine,
+					       struct akcipher_request *req);
+int crypto_transfer_hash_request_to_engine(struct crypto_engine *engine,
+					       struct ahash_request *req);
+int crypto_transfer_kpp_request_to_engine(struct crypto_engine *engine,
+					  struct kpp_request *req);
+int crypto_transfer_skcipher_request_to_engine(struct crypto_engine *engine,
+					       struct skcipher_request *req);
+void crypto_finalize_aead_request(struct crypto_engine *engine,
+				  struct aead_request *req, int err);
+void crypto_finalize_akcipher_request(struct crypto_engine *engine,
+				      struct akcipher_request *req, int err);
+void crypto_finalize_hash_request(struct crypto_engine *engine,
+				  struct ahash_request *req, int err);
+void crypto_finalize_kpp_request(struct crypto_engine *engine,
+				 struct kpp_request *req, int err);
+void crypto_finalize_skcipher_request(struct crypto_engine *engine,
+				      struct skcipher_request *req, int err);
+int crypto_engine_start(struct crypto_engine *engine);
+int crypto_engine_stop(struct crypto_engine *engine);
+struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt);
+struct crypto_engine *crypto_engine_alloc_init_and_set(struct device *dev,
+						       bool retry_support,
+						       bool rt, int qlen);
+void crypto_engine_exit(struct crypto_engine *engine);
+
+int crypto_engine_register_aead(struct aead_engine_alg *alg);
+void crypto_engine_unregister_aead(struct aead_engine_alg *alg);
+int crypto_engine_register_aeads(struct aead_engine_alg *algs, int count);
+void crypto_engine_unregister_aeads(struct aead_engine_alg *algs, int count);
+
+int crypto_engine_register_ahash(struct ahash_engine_alg *alg);
+void crypto_engine_unregister_ahash(struct ahash_engine_alg *alg);
+int crypto_engine_register_ahashes(struct ahash_engine_alg *algs, int count);
+void crypto_engine_unregister_ahashes(struct ahash_engine_alg *algs,
+				      int count);
+
+int crypto_engine_register_akcipher(struct akcipher_engine_alg *alg);
+void crypto_engine_unregister_akcipher(struct akcipher_engine_alg *alg);
+
+int crypto_engine_register_kpp(struct kpp_engine_alg *alg);
+void crypto_engine_unregister_kpp(struct kpp_engine_alg *alg);
+
+int crypto_engine_register_skcipher(struct skcipher_engine_alg *alg);
+void crypto_engine_unregister_skcipher(struct skcipher_engine_alg *alg);
+int crypto_engine_register_skciphers(struct skcipher_engine_alg *algs,
+				     int count);
+void crypto_engine_unregister_skciphers(struct skcipher_engine_alg *algs,
+					int count);
+
+#endif /* _CRYPTO_ENGINE_H */