From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D8914CF489; Sat, 17 Oct 2026 16:29:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792254548; cv=none; b=k3JG+6mkumPDEH3CRl1JYatGIA2MOKtAFaGY7/SGmBbvHWLxEfpCrvLGG3sklEAx0fVrlrhHM2yycMOMcizPsCmp/evpIgWGOEJFnQ60Dhs0PPOeeL/Y9snMRgPRW2WC39vwkXQMnXn/sHEP4A8M/3EpKnoslPNdoLUZnhaMj6Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792254548; c=relaxed/simple; bh=roHXha1e3f4pCy5NajxQSzRbBytgu865nMZauJkIqMo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R/4GmHnPayKd6qEzEf4aUug1wFrg8hjBLQB3KopS6dh2Dr8ZaiDUQJZ1ieWzp4AUwFudlLY40uN8wjExTBX+hOAEUig3A7/hQDLvJhpKysrPohLb8iV1+uDdIfO3VEbqBJKtkSv/DRWQ3cMMPZ6d9jr5Hjga2mjCQSEM0yRN8MI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WOYKNZjC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WOYKNZjC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1036E1F000C4; Sat, 17 Oct 2026 16:29:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792254546; bh=27WkH0W36Wj24nsmpMRekywaliCI+lKVgzOC3YKpHUw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=WOYKNZjC339FMwmK4c/zKB0FXsrlfvh7aj5iKqx5h1YJLDE/iJOPLWTTy0isMVQiH qXga6poBf115IZi8Q9CNsMqEg8DJ7Jz3WM4OqqGUb7OE5eyKA/F3VCcg1CZSmnBuJR F3V5faa3XL60+cNwvs6lUxVvkPVaYulYeY/lQxy4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Harald Freudenberger , Holger Dengler , Heiko Carstens , Sasha Levin Subject: [PATCH 6.12 484/869] s390/ap: Introduce ap message buffer pool Date: Sat, 17 Oct 2026 17:55:25 +0200 Message-ID: <20261017160049.528604244@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160036.979869304@linuxfoundation.org> References: <20261017160036.979869304@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Harald Freudenberger [ Upstream commit dcc160b3a090b1ffa0710ed72ae325be37298c0e ] There is a need for a do-not-allocate-memory path through the AP bus layer. The pkey layer may be triggered via the in-kernel interface from a protected key crypto algorithm (namely PAES) to convert a secure key into a protected key. This happens in a workqueue context, so sleeping is allowed but memory allocations causing IO operations are not permitted. To accomplish this, an AP message memory pool with pre-allocated space is established. When ap_init_apmsg() with use_mempool set to true is called, instead of kmalloc() the ap message buffer is allocated from the ap_msg_pool. This pool only holds a limited amount of buffers: ap_msg_pool_min_items with the item size AP_DEFAULT_MAX_MSG_SIZE and exactly one of these items (if available) is returned if ap_init_apmsg() with the use_mempool arg set to true is called. When this pool is exhausted and use_mempool is set true, ap_init_apmsg() returns -ENOMEM without any attempt to allocate memory and the caller has to deal with that. Default values for this mempool of ap messages is: * Each buffer is 12KB (that is the default AP bus size and all the urgent messages should fit into this space). * Minimum items held in the pool is 8. This value is adjustable via module parameter ap.msgpool_min_items. The zcrypt layer may use this flag to indicate to the ap bus that the processing path for this message should not allocate memory but should use pre-allocated memory buffer instead. This is to prevent deadlocks with crypto and io for example with encrypted swap volumes. Signed-off-by: Harald Freudenberger Reviewed-by: Holger Dengler Link: https://lore.kernel.org/r/20250424133619.16495-4-freude@linux.ibm.com Signed-off-by: Heiko Carstens Stable-dep-of: e935cd525af4 ("s390/zcrypt: Close speculative mem read possibility") Signed-off-by: Sasha Levin --- drivers/s390/crypto/ap_bus.c | 54 ++++++++++++++++++++++++++++++-- drivers/s390/crypto/ap_bus.h | 3 +- drivers/s390/crypto/zcrypt_api.c | 10 +++--- 3 files changed, 58 insertions(+), 9 deletions(-) diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c index 64fed5dbc80f3..4cd88c90c6a8c 100644 --- a/drivers/s390/crypto/ap_bus.c +++ b/drivers/s390/crypto/ap_bus.c @@ -40,6 +40,7 @@ #include #include #include +#include #include "ap_bus.h" #include "ap_debug.h" @@ -101,6 +102,27 @@ static struct ap_config_info *const ap_qci_info_old = &qci[1]; */ debug_info_t *ap_dbf_info; +/* + * There is a need for a do-not-allocate-memory path through the AP bus + * layer. The pkey layer may be triggered via the in-kernel interface from + * a protected key crypto algorithm (namely PAES) to convert a secure key + * into a protected key. This happens in a workqueue context, so sleeping + * is allowed but memory allocations causing IO operations are not permitted. + * To accomplish this, an AP message memory pool with pre-allocated space + * is established. When ap_init_apmsg() with use_mempool set to true is + * called, instead of kmalloc() the ap message buffer is allocated from + * the ap_msg_pool. This pool only holds a limited amount of buffers: + * ap_msg_pool_min_items with the item size AP_DEFAULT_MAX_MSG_SIZE and + * exactly one of these items (if available) is returned if ap_init_apmsg() + * with the use_mempool arg set to true is called. When this pool is exhausted + * and use_mempool is set true, ap_init_apmsg() returns -ENOMEM without + * any attempt to allocate memory and the caller has to deal with that. + */ +static mempool_t *ap_msg_pool; +static unsigned int ap_msg_pool_min_items = 8; +module_param_named(msgpool_min_items, ap_msg_pool_min_items, uint, 0440); +MODULE_PARM_DESC(msgpool_min_items, "AP message pool minimal items"); + /* * AP bus rescan related things. */ @@ -549,11 +571,22 @@ static void ap_poll_thread_stop(void) /* * ap_init_apmsg() - Initialize ap_message. */ -int ap_init_apmsg(struct ap_message *ap_msg) +int ap_init_apmsg(struct ap_message *ap_msg, bool use_mempool) { - unsigned int maxmsgsize = atomic_read(&ap_max_msg_size); + unsigned int maxmsgsize; memset(ap_msg, 0, sizeof(*ap_msg)); + + if (use_mempool) { + ap_msg->msg = mempool_alloc_preallocated(ap_msg_pool); + if (!ap_msg->msg) + return -ENOMEM; + ap_msg->bufsize = AP_DEFAULT_MAX_MSG_SIZE; + ap_msg->flags |= AP_MSG_FLAG_MEMPOOL; + return 0; + } + + maxmsgsize = atomic_read(&ap_max_msg_size); ap_msg->msg = kmalloc(maxmsgsize, GFP_KERNEL); if (!ap_msg->msg) return -ENOMEM; @@ -568,7 +601,12 @@ EXPORT_SYMBOL(ap_init_apmsg); */ void ap_release_apmsg(struct ap_message *ap_msg) { - kfree_sensitive(ap_msg->msg); + if (ap_msg->flags & AP_MSG_FLAG_MEMPOOL) { + memzero_explicit(ap_msg->msg, ap_msg->bufsize); + mempool_free(ap_msg->msg, ap_msg_pool); + } else { + kfree_sensitive(ap_msg->msg); + } } EXPORT_SYMBOL(ap_release_apmsg); @@ -2457,6 +2495,14 @@ static int __init ap_module_init(void) /* init ap_queue hashtable */ hash_init(ap_queues); + /* create ap msg buffer memory pool */ + ap_msg_pool = mempool_create_kmalloc_pool(ap_msg_pool_min_items, + AP_DEFAULT_MAX_MSG_SIZE); + if (!ap_msg_pool) { + rc = -ENOMEM; + goto out; + } + /* set up the AP permissions (ioctls, ap and aq masks) */ ap_perms_init(); @@ -2503,6 +2549,7 @@ static int __init ap_module_init(void) out_bus: bus_unregister(&ap_bus_type); out: + mempool_destroy(ap_msg_pool); ap_debug_exit(); return rc; } @@ -2513,6 +2560,7 @@ static void __exit ap_module_exit(void) ap_irq_exit(); root_device_unregister(ap_root_device); bus_unregister(&ap_bus_type); + mempool_destroy(ap_msg_pool); ap_debug_exit(); } diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h index 8b7cdd58a4ca4..675bc6959d578 100644 --- a/drivers/s390/crypto/ap_bus.h +++ b/drivers/s390/crypto/ap_bus.h @@ -236,8 +236,9 @@ struct ap_message { #define AP_MSG_FLAG_SPECIAL 0x0001 /* flag msg as 'special' with NQAP */ #define AP_MSG_FLAG_USAGE 0x0002 /* CCA, EP11: usage (no admin) msg */ #define AP_MSG_FLAG_ADMIN 0x0004 /* CCA, EP11: admin (=control) msg */ +#define AP_MSG_FLAG_MEMPOOL 0x0008 /* ap msg buffer allocated via mempool */ -int ap_init_apmsg(struct ap_message *ap_msg); +int ap_init_apmsg(struct ap_message *ap_msg, bool use_mempool); void ap_release_apmsg(struct ap_message *ap_msg); enum ap_sm_wait ap_sm_event(struct ap_queue *aq, enum ap_sm_event event); diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c index 543f1dfe1a105..11f9793282b27 100644 --- a/drivers/s390/crypto/zcrypt_api.c +++ b/drivers/s390/crypto/zcrypt_api.c @@ -648,7 +648,7 @@ static long zcrypt_rsa_modexpo(struct ap_perms *perms, trace_s390_zcrypt_req(mex, TP_ICARSAMODEXPO); - rc = ap_init_apmsg(&ap_msg); + rc = ap_init_apmsg(&ap_msg, false); if (rc) goto out; @@ -753,7 +753,7 @@ static long zcrypt_rsa_crt(struct ap_perms *perms, trace_s390_zcrypt_req(crt, TP_ICARSACRT); - rc = ap_init_apmsg(&ap_msg); + rc = ap_init_apmsg(&ap_msg, false); if (rc) goto out; @@ -861,7 +861,7 @@ static long _zcrypt_send_cprb(bool userspace, struct ap_perms *perms, xcrb->status = 0; - rc = ap_init_apmsg(&ap_msg); + rc = ap_init_apmsg(&ap_msg, false); if (rc) goto out; @@ -1045,7 +1045,7 @@ static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms *perms, trace_s390_zcrypt_req(xcrb, TP_ZSENDEP11CPRB); - rc = ap_init_apmsg(&ap_msg); + rc = ap_init_apmsg(&ap_msg, false); if (rc) goto out; @@ -1219,7 +1219,7 @@ static long zcrypt_rng(char *buffer) trace_s390_zcrypt_req(buffer, TP_HWRNGCPRB); - rc = ap_init_apmsg(&ap_msg); + rc = ap_init_apmsg(&ap_msg, false); if (rc) goto out; rc = prep_rng_ap_msg(&ap_msg, &func_code, &domain); -- 2.53.0