crypto: ccp - Check for CCP before registering crypto algs

If the ccp is built as a built-in module, then ccp-crypto (whether
built as a module or a built-in module) will be able to load and
it will register its crypto algorithms.  If the system does not have
a CCP this will result in -ENODEV being returned whenever a command
is attempted to be queued by the registered crypto algorithms.

Add an API, ccp_present(), that checks for the presence of a CCP
on the system.  The ccp-crypto module can use this to determine if it
should register it's crypto alogorithms.

Cc: stable@vger.kernel.org
Reported-by: Scot Doyle <lkml14@scotdoyle.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Scot Doyle <lkml14@scotdoyle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/ccp/ccp-crypto-main.c

@@ -367,6 +367,10 @@ static int ccp_crypto_init(void)
 {
 	int ret;
 
+	ret = ccp_present();
+	if (ret)
+		return ret;
+
 	spin_lock_init(&req_queue_lock);
 	INIT_LIST_HEAD(&req_queue.cmds);
 	req_queue.backlog = &req_queue.cmds;

drivers/crypto/ccp/ccp-dev.c

@@ -54,6 +54,20 @@ static inline void ccp_del_device(struct ccp_device *ccp)
 	ccp_dev = NULL;
 }
 
+/**
+ * ccp_present - check if a CCP device is present
+ *
+ * Returns zero if a CCP device is present, -ENODEV otherwise.
+ */
+int ccp_present(void)
+{
+	if (ccp_get_device())
+		return 0;
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(ccp_present);
+
 /**
  * ccp_enqueue_cmd - queue an operation for processing by the CCP
  *

include/linux/ccp.h

@@ -26,6 +26,13 @@ struct ccp_cmd;
 #if defined(CONFIG_CRYPTO_DEV_CCP_DD) || \
 	defined(CONFIG_CRYPTO_DEV_CCP_DD_MODULE)
 
+/**
+ * ccp_present - check if a CCP device is present
+ *
+ * Returns zero if a CCP device is present, -ENODEV otherwise.
+ */
+int ccp_present(void);
+
 /**
  * ccp_enqueue_cmd - queue an operation for processing by the CCP
  *
@@ -53,6 +60,11 @@ int ccp_enqueue_cmd(struct ccp_cmd *cmd);
 
 #else /* CONFIG_CRYPTO_DEV_CCP_DD is not enabled */
 
+static inline int ccp_present(void)
+{
+	return -ENODEV;
+}
+
 static inline int ccp_enqueue_cmd(struct ccp_cmd *cmd)
 {
 	return -ENODEV;