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Subject[PATCH 3/4] tee: amdtee: check TEE status during driver initialization
Date
The AMD-TEE driver should check if TEE is available before
registering itself with TEE subsystem. This ensures that
there is a TEE which the driver can talk to before proceeding
with tee device node allocation.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Co-developed-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
---
drivers/crypto/ccp/tee-dev.c | 11 +++++++++++
drivers/tee/amdtee/core.c | 6 ++++++
include/linux/psp-tee.h | 18 ++++++++++++++++++
3 files changed, 35 insertions(+)

diff --git a/drivers/crypto/ccp/tee-dev.c b/drivers/crypto/ccp/tee-dev.c
index 555c8a7..5e697a9 100644
--- a/drivers/crypto/ccp/tee-dev.c
+++ b/drivers/crypto/ccp/tee-dev.c
@@ -362,3 +362,14 @@ int psp_tee_process_cmd(enum tee_cmd_id cmd_id, void *buf, size_t len,
return 0;
}
EXPORT_SYMBOL(psp_tee_process_cmd);
+
+int psp_check_tee_status(void)
+{
+ struct psp_device *psp = psp_get_master_device();
+
+ if (!psp || !psp->tee_data)
+ return -ENODEV;
+
+ return 0;
+}
+EXPORT_SYMBOL(psp_check_tee_status);
diff --git a/drivers/tee/amdtee/core.c b/drivers/tee/amdtee/core.c
index dd360f3..9d0cee1 100644
--- a/drivers/tee/amdtee/core.c
+++ b/drivers/tee/amdtee/core.c
@@ -16,6 +16,7 @@
#include <linux/firmware.h>
#include "amdtee_private.h"
#include "../tee_private.h"
+#include <linux/psp-tee.h>

static struct amdtee_driver_data *drv_data;
static DEFINE_MUTEX(session_list_mutex);
@@ -438,6 +439,10 @@ static int __init amdtee_driver_init(void)
struct tee_shm_pool *pool = ERR_PTR(-EINVAL);
int rc;

+ rc = psp_check_tee_status();
+ if (rc)
+ goto err_fail;
+
drv_data = kzalloc(sizeof(*drv_data), GFP_KERNEL);
if (IS_ERR(drv_data))
return -ENOMEM;
@@ -485,6 +490,7 @@ static int __init amdtee_driver_init(void)
kfree(drv_data);
drv_data = NULL;

+err_fail:
pr_err("amd-tee driver initialization failed\n");
return rc;
}
diff --git a/include/linux/psp-tee.h b/include/linux/psp-tee.h
index 63bb221..cb0c95d 100644
--- a/include/linux/psp-tee.h
+++ b/include/linux/psp-tee.h
@@ -62,6 +62,19 @@ enum tee_cmd_id {
int psp_tee_process_cmd(enum tee_cmd_id cmd_id, void *buf, size_t len,
u32 *status);

+/**
+ * psp_check_tee_status() - Checks whether there is a TEE which a driver can
+ * talk to.
+ *
+ * This function can be used by AMD-TEE driver to query if there is TEE with
+ * which it can communicate.
+ *
+ * Returns:
+ * 0 if the device has TEE
+ * -%ENODEV if there is no TEE available
+ */
+int psp_check_tee_status(void);
+
#else /* !CONFIG_CRYPTO_DEV_SP_PSP */

static inline int psp_tee_process_cmd(enum tee_cmd_id cmd_id, void *buf,
@@ -69,5 +82,10 @@ static inline int psp_tee_process_cmd(enum tee_cmd_id cmd_id, void *buf,
{
return -ENODEV;
}
+
+static inline int psp_check_tee_status(void)
+{
+ return -ENODEV;
+}
#endif /* CONFIG_CRYPTO_DEV_SP_PSP */
#endif /* __PSP_TEE_H_ */
--
1.9.1
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