[PATCH bpf-next v5 6/9] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps

[Leon Hwang <leon.hwang@linux.dev>]

Introduce BPF_F_ALL_CPUS flag support for percpu_hash and lru_percpu_hash
maps to allow updating values for all CPUs with a single value for both
update_elem and update_batch APIs.

Introduce BPF_F_CPU flag support for percpu_hash and lru_percpu_hash
maps to allow:

* update value for specified CPU for both update_elem and update_batch
  APIs.
* lookup value for specified CPU for both lookup_elem and lookup_batch
  APIs.

The BPF_F_CPU flag is passed via:

* map_flags along with embedded cpu info.
* elem_flags along with embedded cpu info.

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 include/linux/bpf.h  |  2 ++
 kernel/bpf/hashtab.c | 41 +++++++++++++++++++++++++++++++----------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 67122f852f16d..2254aafc93773 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3756,6 +3756,8 @@ static inline bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type)
 {
 	switch (map_type) {
 	case BPF_MAP_TYPE_PERCPU_ARRAY:
+	case BPF_MAP_TYPE_PERCPU_HASH:
+	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
 		return true;
 	default:
 		return false;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 8955ae8482065..48b45c0945923 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1259,9 +1259,15 @@ static long htab_map_update_elem_in_place(struct bpf_map *map, void *key,
 	u32 key_size, hash;
 	int ret;
 
-	if (unlikely(map_flags > BPF_EXIST))
-		/* unknown flags */
-		return -EINVAL;
+	if (percpu) {
+		ret = bpf_map_check_cpu_flags(map_flags, true);
+		if (unlikely(ret))
+			return ret;
+	} else {
+		if (unlikely(map_flags > BPF_EXIST))
+			/* unknown flags */
+			return -EINVAL;
+	}
 
 	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
 		     !rcu_read_lock_bh_held());
@@ -1322,9 +1328,9 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
 	u32 key_size, hash;
 	int ret;
 
-	if (unlikely(map_flags > BPF_EXIST))
-		/* unknown flags */
-		return -EINVAL;
+	ret = bpf_map_check_cpu_flags(map_flags, true);
+	if (unlikely(ret))
+		return ret;
 
 	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
 		     !rcu_read_lock_bh_held());
@@ -1689,9 +1695,19 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map,
 	int ret = 0;
 
 	elem_map_flags = attr->batch.elem_flags;
-	if ((elem_map_flags & ~BPF_F_LOCK) ||
-	    ((elem_map_flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
-		return -EINVAL;
+	if (!do_delete && is_percpu) {
+		ret = bpf_map_check_lookup_batch_flags(map, elem_map_flags);
+		if (ret)
+			return ret;
+		ret = bpf_map_check_cpu_flags(elem_map_flags, false);
+		if (ret)
+			return ret;
+	} else {
+		if ((elem_map_flags & ~BPF_F_LOCK) ||
+		    ((elem_map_flags & BPF_F_LOCK) &&
+		     !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
+			return -EINVAL;
+	}
 
 	map_flags = attr->batch.flags;
 	if (map_flags)
@@ -2355,8 +2371,13 @@ int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value, u64 map_fl
 {
 	struct htab_elem *l;
 	void __percpu *pptr;
-	int ret = -ENOENT;
 	u32 size;
+	int ret;
+
+	ret = bpf_map_check_cpu_flags(map_flags, false);
+	if (unlikely(ret))
+		return ret;
+	ret = -ENOENT;
 
 	/* per_cpu areas are zero-filled and bpf programs can only
 	 * access 'value_size' of them, so copying rounded areas
-- 
2.50.1