1 files changed, 74 insertions, 0 deletions

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 1564cd7e3f59..288734cd8f4b 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -41,6 +41,7 @@
 #include <linux/module.h>
 #include <asm/uv.h>
 #include <asm/chsc.h>
+#include <linux/mempool.h>
 
 #include "ap_bus.h"
 #include "ap_debug.h"
@@ -103,6 +104,27 @@ 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.
  */
 static bool ap_scan_bus(void);
@@ -547,6 +569,48 @@ static void ap_poll_thread_stop(void)
 #define is_card_dev(x) ((x)->parent == ap_root_device)
 #define is_queue_dev(x) ((x)->parent != ap_root_device)
 
+/*
+ * ap_init_apmsg() - Initialize ap_message.
+ */
+int ap_init_apmsg(struct ap_message *ap_msg, u32 flags)
+{
+	unsigned int maxmsgsize;
+
+	memset(ap_msg, 0, sizeof(*ap_msg));
+	ap_msg->flags = flags;
+
+	if (flags & AP_MSG_FLAG_MEMPOOL) {
+		ap_msg->msg = mempool_alloc_preallocated(ap_msg_pool);
+		if (!ap_msg->msg)
+			return -ENOMEM;
+		ap_msg->bufsize = AP_DEFAULT_MAX_MSG_SIZE;
+		return 0;
+	}
+
+	maxmsgsize = atomic_read(&ap_max_msg_size);
+	ap_msg->msg = kmalloc(maxmsgsize, GFP_KERNEL);
+	if (!ap_msg->msg)
+		return -ENOMEM;
+	ap_msg->bufsize = maxmsgsize;
+
+	return 0;
+}
+EXPORT_SYMBOL(ap_init_apmsg);
+
+/*
+ * ap_release_apmsg() - Release ap_message.
+ */
+void ap_release_apmsg(struct ap_message *ap_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);
+
 /**
  * ap_bus_match()
  * @dev: Pointer to device
@@ -2431,6 +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();
 
@@ -2477,6 +2549,7 @@ out_device:
 out_bus:
 	bus_unregister(&ap_bus_type);
 out:
+	mempool_destroy(ap_msg_pool);
 	ap_debug_exit();
 	return rc;
 }
@@ -2487,6 +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();
 }