AMD-TEE reference count loaded TAs

-----BEGIN PGP SIGNATURE-----
 
 iQJOBAABCgA4FiEEFV+gSSXZJY9ZyuB5LinzTIcAHJcFAmCSeuwaHGplbnMud2lr
 bGFuZGVyQGxpbmFyby5vcmcACgkQLinzTIcAHJe/rA//QN3OBBD0K2kx8gBD2Lxb
 4oaJEjgJAJPoT8qGLPVZcYDXUkNIjx78fz+IPNVtJamaw9c6jDMXe/wB21QFmruy
 ZcOP0+cfk0ytCcsHAeY9CICjWA7c73fq89VOmT8upv54m1dGSV8Qat5rarJTNJ4T
 7WNybzsUeCOHbxJky4BtnXV/l/9w0gpwrlB47fChGPCvadGeP3LsKkcNIsNWdNQa
 VrYNqXCL2cQIELExeH0ZqaIlQpXFwiJdTseBBL69DwKw/QZuxH2U+Qr1vAUuPKL8
 EzGQnHYcmuzmDsITUAnSnzo8zc9A9yRcR6CTM+wK8Q+n8L8dIWzSjEiQZCisEWzX
 DURJK2oHLhTEovpEhHUEDOmQk892IHIDGAMr5hwXMaALmA+ruGyObMCtAxnFBItw
 hL9FkXcWpXXS0pJZXs60lwBtebC823nVhvZtjA5ek2RSJM8YiQLVP8acDZ/zbt/Q
 AG9ZLuTO2tYUS4qWRW8V7j+gA+CveKbVZH3/RuCBtk1BxupTZ/8EjaQwN5wBkJgP
 ohHog59ZNydCkaJkN9vM/DenG+OAQz6wN6GYGbaeXMV873z/6WSa/pc/WE1dLF/B
 Dpnyafefi9luN1O7vZrbrX+/4CHkeirOYS1kSCxz+PF0RCAXIuWuj6NWJPmyUAnT
 mVOY0V9naDFVYboE5HFdwww=
 =aCPL
 -----END PGP SIGNATURE-----

Merge tag 'amdtee-fixes-for-v5.13' of git://git.linaro.org/people/jens.wiklander/linux-tee into arm/fixes

AMD-TEE reference count loaded TAs

* tag 'amdtee-fixes-for-v5.13' of git://git.linaro.org/people/jens.wiklander/linux-tee:
  tee: amdtee: unload TA only when its refcount becomes 0

Link: https://lore.kernel.org/r/20210505110850.GA3434209@jade
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/tee/amdtee/amdtee_private.h

@@ -21,6 +21,7 @@
 #define TEEC_SUCCESS			0x00000000
 #define TEEC_ERROR_GENERIC		0xFFFF0000
 #define TEEC_ERROR_BAD_PARAMETERS	0xFFFF0006
+#define TEEC_ERROR_OUT_OF_MEMORY	0xFFFF000C
 #define TEEC_ERROR_COMMUNICATION	0xFFFF000E
 
 #define TEEC_ORIGIN_COMMS		0x00000002
@@ -93,6 +94,18 @@ struct amdtee_shm_data {
 	u32     buf_id;
 };
 
+/**
+ * struct amdtee_ta_data - Keeps track of all TAs loaded in AMD Secure
+ *			   Processor
+ * @ta_handle:	Handle to TA loaded in TEE
+ * @refcount:	Reference count for the loaded TA
+ */
+struct amdtee_ta_data {
+	struct list_head list_node;
+	u32 ta_handle;
+	u32 refcount;
+};
+
 #define LOWER_TWO_BYTE_MASK	0x0000FFFF
 
 /**

drivers/tee/amdtee/call.c

@@ -121,15 +121,69 @@ static int amd_params_to_tee_params(struct tee_param *tee, u32 count,
 	return ret;
 }
 
+static DEFINE_MUTEX(ta_refcount_mutex);
+static struct list_head ta_list = LIST_HEAD_INIT(ta_list);
+
+static u32 get_ta_refcount(u32 ta_handle)
+{
+	struct amdtee_ta_data *ta_data;
+	u32 count = 0;
+
+	/* Caller must hold a mutex */
+	list_for_each_entry(ta_data, &ta_list, list_node)
+		if (ta_data->ta_handle == ta_handle)
+			return ++ta_data->refcount;
+
+	ta_data = kzalloc(sizeof(*ta_data), GFP_KERNEL);
+	if (ta_data) {
+		ta_data->ta_handle = ta_handle;
+		ta_data->refcount = 1;
+		count = ta_data->refcount;
+		list_add(&ta_data->list_node, &ta_list);
+	}
+
+	return count;
+}
+
+static u32 put_ta_refcount(u32 ta_handle)
+{
+	struct amdtee_ta_data *ta_data;
+	u32 count = 0;
+
+	/* Caller must hold a mutex */
+	list_for_each_entry(ta_data, &ta_list, list_node)
+		if (ta_data->ta_handle == ta_handle) {
+			count = --ta_data->refcount;
+			if (count == 0) {
+				list_del(&ta_data->list_node);
+				kfree(ta_data);
+				break;
+			}
+		}
+
+	return count;
+}
+
 int handle_unload_ta(u32 ta_handle)
 {
 	struct tee_cmd_unload_ta cmd = {0};
-	u32 status;
+	u32 status, count;
 	int ret;
 
 	if (!ta_handle)
 		return -EINVAL;
 
+	mutex_lock(&ta_refcount_mutex);
+
+	count = put_ta_refcount(ta_handle);
+
+	if (count) {
+		pr_debug("unload ta: not unloading %u count %u\n",
+			 ta_handle, count);
+		ret = -EBUSY;
+		goto unlock;
+	}
+
 	cmd.ta_handle = ta_handle;
 
 	ret = psp_tee_process_cmd(TEE_CMD_ID_UNLOAD_TA, (void *)&cmd,
@@ -137,8 +191,12 @@ int handle_unload_ta(u32 ta_handle)
 	if (!ret && status != 0) {
 		pr_err("unload ta: status = 0x%x\n", status);
 		ret = -EBUSY;
+	} else {
+		pr_debug("unloaded ta handle %u\n", ta_handle);
 	}
 
+unlock:
+	mutex_unlock(&ta_refcount_mutex);
 	return ret;
 }
 
@@ -340,7 +398,8 @@ int handle_open_session(struct tee_ioctl_open_session_arg *arg, u32 *info,
 
 int handle_load_ta(void *data, u32 size, struct tee_ioctl_open_session_arg *arg)
 {
-	struct tee_cmd_load_ta cmd = {0};
+	struct tee_cmd_unload_ta unload_cmd = {};
+	struct tee_cmd_load_ta load_cmd = {};
 	phys_addr_t blob;
 	int ret;
 
@@ -353,21 +412,36 @@ int handle_load_ta(void *data, u32 size, struct tee_ioctl_open_session_arg *arg)
 		return -EINVAL;
 	}
 
-	cmd.hi_addr = upper_32_bits(blob);
-	cmd.low_addr = lower_32_bits(blob);
-	cmd.size = size;
+	load_cmd.hi_addr = upper_32_bits(blob);
+	load_cmd.low_addr = lower_32_bits(blob);
+	load_cmd.size = size;
 
-	ret = psp_tee_process_cmd(TEE_CMD_ID_LOAD_TA, (void *)&cmd,
-				  sizeof(cmd), &arg->ret);
+	mutex_lock(&ta_refcount_mutex);
+
+	ret = psp_tee_process_cmd(TEE_CMD_ID_LOAD_TA, (void *)&load_cmd,
+				  sizeof(load_cmd), &arg->ret);
 	if (ret) {
 		arg->ret_origin = TEEC_ORIGIN_COMMS;
 		arg->ret = TEEC_ERROR_COMMUNICATION;
-	} else {
-		set_session_id(cmd.ta_handle, 0, &arg->session);
+	} else if (arg->ret == TEEC_SUCCESS) {
+		ret = get_ta_refcount(load_cmd.ta_handle);
+		if (!ret) {
+			arg->ret_origin = TEEC_ORIGIN_COMMS;
+			arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
+
+			/* Unload the TA on error */
+			unload_cmd.ta_handle = load_cmd.ta_handle;
+			psp_tee_process_cmd(TEE_CMD_ID_UNLOAD_TA,
+					    (void *)&unload_cmd,
+					    sizeof(unload_cmd), &ret);
+		} else {
+			set_session_id(load_cmd.ta_handle, 0, &arg->session);
+		}
 	}
+	mutex_unlock(&ta_refcount_mutex);
 
 	pr_debug("load TA: TA handle = 0x%x, RO = 0x%x, ret = 0x%x\n",
-		 cmd.ta_handle, arg->ret_origin, arg->ret);
+		 load_cmd.ta_handle, arg->ret_origin, arg->ret);
 
 	return 0;
 }

drivers/tee/amdtee/core.c

@@ -59,10 +59,9 @@ static void release_session(struct amdtee_session *sess)
 			continue;
 
 		handle_close_session(sess->ta_handle, sess->session_info[i]);
+		handle_unload_ta(sess->ta_handle);
 	}
 
-	/* Unload Trusted Application once all sessions are closed */
-	handle_unload_ta(sess->ta_handle);
 	kfree(sess);
 }
 
@@ -224,8 +223,6 @@ static void destroy_session(struct kref *ref)
 	struct amdtee_session *sess = container_of(ref, struct amdtee_session,
 						   refcount);
 
-	/* Unload the TA from TEE */
-	handle_unload_ta(sess->ta_handle);
 	mutex_lock(&session_list_mutex);
 	list_del(&sess->list_node);
 	mutex_unlock(&session_list_mutex);
@@ -238,7 +235,7 @@ int amdtee_open_session(struct tee_context *ctx,
 {
 	struct amdtee_context_data *ctxdata = ctx->data;
 	struct amdtee_session *sess = NULL;
-	u32 session_info;
+	u32 session_info, ta_handle;
 	size_t ta_size;
 	int rc, i;
 	void *ta;
@@ -259,11 +256,14 @@ int amdtee_open_session(struct tee_context *ctx,
 	if (arg->ret != TEEC_SUCCESS)
 		goto out;
 
+	ta_handle = get_ta_handle(arg->session);
+
 	mutex_lock(&session_list_mutex);
 	sess = alloc_session(ctxdata, arg->session);
 	mutex_unlock(&session_list_mutex);
 
 	if (!sess) {
+		handle_unload_ta(ta_handle);
 		rc = -ENOMEM;
 		goto out;
 	}
@@ -277,6 +277,7 @@ int amdtee_open_session(struct tee_context *ctx,
 
 	if (i >= TEE_NUM_SESSIONS) {
 		pr_err("reached maximum session count %d\n", TEE_NUM_SESSIONS);
+		handle_unload_ta(ta_handle);
 		kref_put(&sess->refcount, destroy_session);
 		rc = -ENOMEM;
 		goto out;
@@ -289,12 +290,13 @@ int amdtee_open_session(struct tee_context *ctx,
 		spin_lock(&sess->lock);
 		clear_bit(i, sess->sess_mask);
 		spin_unlock(&sess->lock);
+		handle_unload_ta(ta_handle);
 		kref_put(&sess->refcount, destroy_session);
 		goto out;
 	}
 
 	sess->session_info[i] = session_info;
-	set_session_id(sess->ta_handle, i, &arg->session);
+	set_session_id(ta_handle, i, &arg->session);
 out:
 	free_pages((u64)ta, get_order(ta_size));
 	return rc;
@@ -329,6 +331,7 @@ int amdtee_close_session(struct tee_context *ctx, u32 session)
 
 	/* Close the session */
 	handle_close_session(ta_handle, session_info);
+	handle_unload_ta(ta_handle);
 
 	kref_put(&sess->refcount, destroy_session);