[PATCH v3 05/21] s390/zcrypt: Introduce cprb mempool for cca misc functions

Harald Freudenberger
2025-03-27T14:39:52Z

Introduce a new module parameter "zcrypt_mempool_threshold"
for the zcrypt module. This parameter controls the minimal
amount of mempool items which are pre-allocated for urgent
requests/replies and will be used with the support for the
new xflag ZCRYPT_XFLAG_NOMEMALLOC. The default value of 5
shall provide enough memory items to support up to 5 requests
(and their associated reply) in parallel.

For CCA each mempool item is 16KB, as a CCA CPRB needs to
hold the request and the reply. The pool items only support
requests/replies with a limit of about 8KB.
So by default the CCA mempool consumes
5 * 16KB = 80KB

This is only part of an rework to support a new xflag
ZCRYPT_XFLAG_NOMEMALLOC but not yet complete.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
---
drivers/s390/crypto/zcrypt_api.c | 13 ++-
drivers/s390/crypto/zcrypt_api.h | 2 +
drivers/s390/crypto/zcrypt_ccamisc.c | 117 ++++++++++++++++++++-------
drivers/s390/crypto/zcrypt_ccamisc.h | 1 +
4 files changed, 102 insertions(+), 31 deletions(-)

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 01cb72fed828..cca7d7fdf644 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -50,6 +50,10 @@ MODULE_DESCRIPTION("Cryptographic Coprocessor interface, " \
"Copyright IBM Corp. 2001, 2012");
MODULE_LICENSE("GPL");

+unsigned int zcrypt_mempool_threshold = 5;
+module_param_named(mempool_threshold, zcrypt_mempool_threshold, uint, 0440);
+MODULE_PARM_DESC(mempool_threshold, "CCA and EP11 request/reply mempool minimal items.");
+
/*
* zcrypt tracepoint functions
*/
@@ -2157,7 +2161,11 @@ int __init zcrypt_api_init(void)

rc = zcdn_init();
if (rc)
- goto out;
+ goto out_zcdn_init_failed;
+
+ rc = zcrypt_ccamisc_init();
+ if (rc)
+ goto out_ccamisc_init_failed;

/* Register the request sprayer. */
rc = misc_register(&zcrypt_misc_device);
@@ -2170,7 +2178,10 @@ int __init zcrypt_api_init(void)
return 0;

out_misc_register_failed:
+ zcrypt_ccamisc_exit();
+out_ccamisc_init_failed:
zcdn_exit();
+out_zcdn_init_failed:
zcrypt_debug_exit();
out:
return rc;
diff --git a/drivers/s390/crypto/zcrypt_api.h b/drivers/s390/crypto/zcrypt_api.h
index b1e2e8804932..5112cdc35ee2 100644
--- a/drivers/s390/crypto/zcrypt_api.h
+++ b/drivers/s390/crypto/zcrypt_api.h
@@ -139,6 +139,8 @@ extern atomic_t zcrypt_rescan_req;
extern spinlock_t zcrypt_list_lock;
extern struct list_head zcrypt_card_list;

+extern unsigned int zcrypt_mempool_threshold;
+
#define for_each_zcrypt_card(_zc) \
list_for_each_entry(_zc, &zcrypt_card_list, list)

diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c b/drivers/s390/crypto/zcrypt_ccamisc.c
index 521baaea06ff..a2d7facac085 100644
--- a/drivers/s390/crypto/zcrypt_ccamisc.c
+++ b/drivers/s390/crypto/zcrypt_ccamisc.c
@@ -11,6 +11,7 @@
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/init.h>
+#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/random.h>
@@ -40,6 +41,16 @@ struct cca_info_list_entry {
static LIST_HEAD(cca_info_list);
static DEFINE_SPINLOCK(cca_info_list_lock);

+/*
+ * Cprb memory pool held for urgent cases where no memory
+ * can be allocated via kmalloc. This pool is only used
+ * when alloc_and_prep_cprbmem() is called with the xflag
+ * ZCRYPT_XFLAG_NOMEMALLOC. The cprb memory needs to hold
+ * space for request AND reply!
+ */
+#define CPRB_MEMPOOL_ITEM_SIZE (16 * 1024)
+static mempool_t *cprb_mempool;
+
/*
* Simple check if the token is a valid CCA secure AES data key
* token. If keybitsize is given, the bitsize of the key is
@@ -219,9 +230,10 @@ EXPORT_SYMBOL(cca_check_sececckeytoken);
static int alloc_and_prep_cprbmem(size_t paramblen,
u8 **p_cprb_mem,
struct CPRBX **p_req_cprb,
- struct CPRBX **p_rep_cprb)
+ struct CPRBX **p_rep_cprb,
+ u32 xflags)
{
- u8 *cprbmem;
+ u8 *cprbmem = NULL;
size_t cprbplusparamblen = sizeof(struct CPRBX) + paramblen;
struct CPRBX *preqcblk, *prepcblk;

@@ -229,7 +241,16 @@ static int alloc_and_prep_cprbmem(size_t paramblen,
* allocate consecutive memory for request CPRB, request param
* block, reply CPRB and reply param block
*/
- cprbmem = kcalloc(2, cprbplusparamblen, GFP_KERNEL);
+ if (xflags & ZCRYPT_XFLAG_NOMEMALLOC) {
+ size_t len = 2 * cprbplusparamblen;
+
+ if (cprb_mempool && len <= CPRB_MEMPOOL_ITEM_SIZE) {
+ cprbmem = mempool_alloc_preallocated(cprb_mempool);
+ memset(cprbmem, 0, len);
+ }
+ } else {
+ cprbmem = kcalloc(2, cprbplusparamblen, GFP_KERNEL);
+ }
if (!cprbmem)
return -ENOMEM;

@@ -261,11 +282,15 @@ static int alloc_and_prep_cprbmem(size_t paramblen,
* with zeros before freeing (useful if there was some
* clear key material in there).
*/
-static void free_cprbmem(void *mem, size_t paramblen, int scrub)
+static void free_cprbmem(void *mem, size_t paramblen, bool scrub, u32 xflags)
{
if (scrub)
memzero_explicit(mem, 2 * (sizeof(struct CPRBX) + paramblen));
- kfree(mem);
+
+ if (xflags & ZCRYPT_XFLAG_NOMEMALLOC)
+ mempool_free(mem, cprb_mempool);
+ else
+ kfree(mem);
}

/*
@@ -330,9 +355,11 @@ int cca_genseckey(u16 cardnr, u16 domain,
} keyblock;
} lv3;
} __packed * prepparm;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -379,7 +406,7 @@ int cca_genseckey(u16 cardnr, u16 domain,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, errno %d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -424,7 +451,7 @@ int cca_genseckey(u16 cardnr, u16 domain,
memcpy(seckey, prepparm->lv3.keyblock.tok, SECKEYBLOBSIZE);

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, false, xflags);
return rc;
}
EXPORT_SYMBOL(cca_genseckey);
@@ -471,9 +498,11 @@ int cca_clr2seckey(u16 cardnr, u16 domain, u32 keybitsize,
} keyblock;
} lv3;
} __packed * prepparm;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -517,7 +546,7 @@ int cca_clr2seckey(u16 cardnr, u16 domain, u32 keybitsize,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -563,7 +592,7 @@ int cca_clr2seckey(u16 cardnr, u16 domain, u32 keybitsize,
memcpy(seckey, prepparm->lv3.keyblock.tok, SECKEYBLOBSIZE);

out:
- free_cprbmem(mem, PARMBSIZE, 1);
+ free_cprbmem(mem, PARMBSIZE, true, xflags);
return rc;
}
EXPORT_SYMBOL(cca_clr2seckey);
@@ -617,9 +646,11 @@ int cca_sec2protkey(u16 cardnr, u16 domain,
} ckb;
} lv3;
} __packed * prepparm;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -644,7 +675,7 @@ int cca_sec2protkey(u16 cardnr, u16 domain,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -712,7 +743,7 @@ int cca_sec2protkey(u16 cardnr, u16 domain,
*protkeylen = prepparm->lv3.ckb.len;

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, true, xflags);
return rc;
}
EXPORT_SYMBOL(cca_sec2protkey);
@@ -811,9 +842,11 @@ int cca_gencipherkey(u16 cardnr, u16 domain, u32 keybitsize, u32 keygenflags,
} kb;
} __packed * prepparm;
struct cipherkeytoken *t;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -872,7 +905,7 @@ int cca_gencipherkey(u16 cardnr, u16 domain, u32 keybitsize, u32 keygenflags,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -923,7 +956,7 @@ int cca_gencipherkey(u16 cardnr, u16 domain, u32 keybitsize, u32 keygenflags,
*keybufsize = t->len;

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, false, xflags);
return rc;
}
EXPORT_SYMBOL(cca_gencipherkey);
@@ -987,9 +1020,11 @@ static int _ip_cprb_helper(u16 cardnr, u16 domain,
} __packed * prepparm;
struct cipherkeytoken *t;
int complete = strncmp(rule_array_2, "COMPLETE", 8) ? 0 : 1;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -1038,7 +1073,7 @@ static int _ip_cprb_helper(u16 cardnr, u16 domain,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -1077,7 +1112,7 @@ static int _ip_cprb_helper(u16 cardnr, u16 domain,
*key_token_size = t->len;

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, false, xflags);
return rc;
}

@@ -1217,9 +1252,11 @@ int cca_cipher2protkey(u16 cardnr, u16 domain, const u8 *ckey,
} kb;
} __packed * prepparm;
int keytoklen = ((struct cipherkeytoken *)ckey)->len;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -1249,7 +1286,7 @@ int cca_cipher2protkey(u16 cardnr, u16 domain, const u8 *ckey,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -1323,7 +1360,7 @@ int cca_cipher2protkey(u16 cardnr, u16 domain, const u8 *ckey,
*protkeylen = prepparm->vud.ckb.keylen;

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, true, xflags);
return rc;
}
EXPORT_SYMBOL(cca_cipher2protkey);
@@ -1380,9 +1417,11 @@ int cca_ecc2protkey(u16 cardnr, u16 domain, const u8 *key,
/* followed by a key block */
} __packed * prepparm;
int keylen = ((struct eccprivkeytoken *)key)->len;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -1412,7 +1451,7 @@ int cca_ecc2protkey(u16 cardnr, u16 domain, const u8 *key,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -1470,7 +1509,7 @@ int cca_ecc2protkey(u16 cardnr, u16 domain, const u8 *key,
*protkeytype = PKEY_KEYTYPE_ECC;

out:
- free_cprbmem(mem, PARMBSIZE, 0);
+ free_cprbmem(mem, PARMBSIZE, true, xflags);
return rc;
}
EXPORT_SYMBOL(cca_ecc2protkey);
@@ -1503,9 +1542,11 @@ int cca_query_crypto_facility(u16 cardnr, u16 domain,
u8 subfunc_code[2];
u8 lvdata[];
} __packed * prepparm;
+ const u32 xflags = 0;

/* get already prepared memory for 2 cprbs with param block each */
- rc = alloc_and_prep_cprbmem(parmbsize, &mem, &preqcblk, &prepcblk);
+ rc = alloc_and_prep_cprbmem(parmbsize, &mem,
+ &preqcblk, &prepcblk, xflags);
if (rc)
return rc;

@@ -1526,7 +1567,7 @@ int cca_query_crypto_facility(u16 cardnr, u16 domain,
prep_xcrb(&xcrb, cardnr, preqcblk, prepcblk);

/* forward xcrb with request CPRB and reply CPRB to zcrypt dd */
- rc = zcrypt_send_cprb(&xcrb, 0);
+ rc = zcrypt_send_cprb(&xcrb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_cprb (cardnr=%d domain=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -1573,7 +1614,7 @@ int cca_query_crypto_facility(u16 cardnr, u16 domain,
}

out:
- free_cprbmem(mem, parmbsize, 0);
+ free_cprbmem(mem, parmbsize, false, xflags);
return rc;
}
EXPORT_SYMBOL(cca_query_crypto_facility);
@@ -1959,7 +2000,23 @@ int cca_findcard2(u32 **apqns, u32 *nr_apqns, u16 cardnr, u16 domain,
}
EXPORT_SYMBOL(cca_findcard2);

-void __exit zcrypt_ccamisc_exit(void)
+int __init zcrypt_ccamisc_init(void)
+{
+ /* Pre-allocate a small memory pool for cca cprbs. */
+ cprb_mempool = mempool_create_kmalloc_pool(zcrypt_mempool_threshold,
+ CPRB_MEMPOOL_ITEM_SIZE);
+ if (IS_ERR(cprb_mempool)) {
+ ZCRYPT_DBF_ERR("%s mempool_create(%d,%d) failed: %ld\n",
+ __func__, zcrypt_mempool_threshold,
+ CPRB_MEMPOOL_ITEM_SIZE, PTR_ERR(cprb_mempool));
+ cprb_mempool = NULL;
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void zcrypt_ccamisc_exit(void)
{
mkvp_cache_free();
+ mempool_destroy(cprb_mempool);
}
diff --git a/drivers/s390/crypto/zcrypt_ccamisc.h b/drivers/s390/crypto/zcrypt_ccamisc.h
index 26bdca702523..273edf2bb036 100644
--- a/drivers/s390/crypto/zcrypt_ccamisc.h
+++ b/drivers/s390/crypto/zcrypt_ccamisc.h
@@ -272,6 +272,7 @@ struct cca_info {
*/
int cca_get_info(u16 card, u16 dom, struct cca_info *ci, int verify);

+int zcrypt_ccamisc_init(void);
void zcrypt_ccamisc_exit(void);

#endif /* _ZCRYPT_CCAMISC_H_ */
--
2.43.0