Hi Vladimir,

quoted

--- /dev/null
+++ b/lib/librte_hash/k32v64_hash.c

@@ -0,0 +1,277 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2020 Intel Corporation
+ */
+
+#include <string.h>
+
+#include <rte_errno.h>
+#include <rte_malloc.h>
+#include <rte_memory.h>
+
+#include "k32v64_hash.h"
+
+static inline int
+k32v64_hash_lookup(struct k32v64_hash_table *table, uint32_t key,
+	uint32_t hash, uint64_t *value)
+{
+	return __k32v64_hash_lookup(table, key, hash, value, __kv_cmp_keys);
+}
+
+static int
+k32v64_hash_bulk_lookup(struct rte_kv_hash_table *ht, void *keys_p,
+	uint32_t *hashes, void *values_p, unsigned int n)
+{
+	struct k32v64_hash_table *table = (struct k32v64_hash_table *)ht;
+	uint32_t *keys = keys_p;
+	uint64_t *values = values_p;
+	int ret, cnt = 0;
+	unsigned int i;
+
+	if (unlikely((table == NULL) || (keys == NULL) || (hashes == NULL) ||
+			(values == NULL)))
+		return -EINVAL;

As a nit - this formal parameter checking better to do in public function
(rte_kv_hash_bulk_lookup) before de-refencing table and calling actual lookup().  
Same story for modify() - formal parameter checking can be done at the top of public function.
BTW, why to unite add/delete into modify(), if internally you have 2 different functions
(for add/delete) anyway?

quoted

+
+	for (i = 0; i < n; i++) {
+		ret = k32v64_hash_lookup(table, keys[i], hashes[i],
+			&values[i]);
+		if (ret == 0)
+			cnt++;
+	}
+	return cnt;
+}
+
+#ifdef CC_AVX512VL_SUPPORT
+int
+k32v64_hash_bulk_lookup_avx512vl(struct rte_kv_hash_table *ht,
+	void *keys_p, uint32_t *hashes, void *values_p, unsigned int n);
+#endif
+
+static rte_kv_hash_bulk_lookup_t
+get_lookup_bulk_fn(void)
+{
+#ifdef CC_AVX512VL_SUPPORT
+	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX512VL))
+		return k32v64_hash_bulk_lookup_avx512vl;
+#endif
+	return k32v64_hash_bulk_lookup;
+}
+
+static int
+k32v64_hash_add(struct k32v64_hash_table *table, uint32_t key,
+	uint32_t hash, uint64_t value, uint64_t *old_value, int *found)
+{
+	uint32_t bucket;
+	int i, idx, ret;
+	uint8_t msk;
+	struct k32v64_ext_ent *tmp, *ent, *prev = NULL;
+
+	if (table == NULL)
+		return -EINVAL;
+
+	bucket = hash & table->bucket_msk;
+	/* Search key in table. Update value if exists */
+	for (i = 0; i < K32V64_KEYS_PER_BUCKET; i++) {
+		if ((key == table->t[bucket].key[i]) &&
+				(table->t[bucket].key_mask & (1 << i))) {
+			*old_value = table->t[bucket].val[i];
+			*found = 1;
+			__atomic_fetch_add(&table->t[bucket].cnt, 1,
+				__ATOMIC_ACQUIRE);

After another thought - atomic add is probably an overkill here.
Something like:
void update_start(struct k32v64_hash_bucket *bkt)
{
	bkt->cnt++;
        __atomic_thread_fence(__ATOMIC_ACQ_REL);
}

void update_finish(struct k32v64_hash_bucket *bkt)
{
	__atomic_thread_fence(__ATOMIC_ACQ_REL);
	bkt->cnt++;
}

I think should be sufficient here.

quoted

+			table->t[bucket].val[i] = value;
+			__atomic_fetch_add(&table->t[bucket].cnt, 1,
+				__ATOMIC_RELEASE);
+			return 0;
+		}
+	}
+
+	if (!SLIST_EMPTY(&table->t[bucket].head)) {
+		SLIST_FOREACH(ent, &table->t[bucket].head, next) {
+			if (ent->key == key) {
+				*old_value = ent->val;
+				*found = 1;
+				__atomic_fetch_add(&table->t[bucket].cnt, 1,
+					__ATOMIC_ACQUIRE);
+				ent->val = value;
+				__atomic_fetch_add(&table->t[bucket].cnt, 1,
+					__ATOMIC_RELEASE);
+				return 0;
+			}
+		}
+	}
+
+	msk = ~table->t[bucket].key_mask & VALID_KEY_MSK;
+	if (msk) {
+		idx = __builtin_ctz(msk);
+		table->t[bucket].key[idx] = key;
+		table->t[bucket].val[idx] = value;
+		__atomic_or_fetch(&table->t[bucket].key_mask, 1 << idx,
+			__ATOMIC_RELEASE);

I think this case also has to guarded with table->t[bucket].cnt updates.

quoted

+		table->nb_ent++;
+		*found = 0;
+		return 0;
+	}
+
+	ret = rte_mempool_get(table->ext_ent_pool, (void **)&ent);
+	if (ret < 0)
+		return ret;
+
+	SLIST_NEXT(ent, next) = NULL;
+	ent->key = key;
+	ent->val = value;
+	rte_smp_wmb();

__atomic_thread_fence(__ATOMIC_RELEASE);
?

quoted

+	SLIST_FOREACH(tmp, &table->t[bucket].head, next)
+		prev = tmp;
+
+	if (prev == NULL)
+		SLIST_INSERT_HEAD(&table->t[bucket].head, ent, next);
+	else
+		SLIST_INSERT_AFTER(prev, ent, next);
+
+	table->nb_ent++;
+	table->nb_ext_ent++;
+	*found = 0;
+	return 0;
+}
+
+static int
+k32v64_hash_delete(struct k32v64_hash_table *table, uint32_t key,
+	uint32_t hash, uint64_t *old_value)
+{
+	uint32_t bucket;
+	int i;
+	struct k32v64_ext_ent *ent;
+
+	if (table == NULL)
+		return -EINVAL;
+
+	bucket = hash & table->bucket_msk;
+
+	for (i = 0; i < K32V64_KEYS_PER_BUCKET; i++) {
+		if ((key == table->t[bucket].key[i]) &&
+				(table->t[bucket].key_mask & (1 << i))) {
+			*old_value = table->t[bucket].val[i];
+			ent = SLIST_FIRST(&table->t[bucket].head);
+			if (ent) {
+				__atomic_fetch_add(&table->t[bucket].cnt, 1,
+					__ATOMIC_ACQUIRE);
+				table->t[bucket].key[i] = ent->key;
+				table->t[bucket].val[i] = ent->val;
+				SLIST_REMOVE_HEAD(&table->t[bucket].head, next);
+				__atomic_fetch_add(&table->t[bucket].cnt, 1,
+					__ATOMIC_RELEASE);
+				table->nb_ext_ent--;
+			} else
+				__atomic_and_fetch(&table->t[bucket].key_mask,
+					~(1 << i), __ATOMIC_RELEASE);

Same thought as above - safer to guard this mask update with cnt update.

quoted

+			if (ent)
+				rte_mempool_put(table->ext_ent_pool, ent);

Can't this 'if(ent)' be merged with previous 'if (ent) {...}' above?

quoted

+			table->nb_ent--;
+			return 0;
+		}
+	}
+
+	SLIST_FOREACH(ent, &table->t[bucket].head, next)
+		if (ent->key == key)
+			break;
+
+	if (ent == NULL)
+		return -ENOENT;
+
+	*old_value = ent->val;
+
+	__atomic_fetch_add(&table->t[bucket].cnt, 1, __ATOMIC_ACQUIRE);
+	SLIST_REMOVE(&table->t[bucket].head, ent, k32v64_ext_ent, next);
+	__atomic_fetch_add(&table->t[bucket].cnt, 1, __ATOMIC_RELEASE);
+	rte_mempool_put(table->ext_ent_pool, ent);
+
+	table->nb_ext_ent--;
+	table->nb_ent--;
+
+	return 0;
+}
+