[PATCH v1 07/14] tee: optee: add shared buffer registration functions

[Volodymyr Babchuk]

From: Volodymyr Babchuk <vlad.babchuk at gmail.com>

This change adds ops for shm_(un)register functions in tee interface.
Client application can use these functions to (un)register an own shared
buffer in OP-TEE address space. This allows zero copy data sharing between
Normal and Secure Worlds.

Please note that while those functions were added to optee code,
it does not report to userspace that those functions are available.
OP-TEE code does not set TEE_GEN_CAP_REG_MEM flag. This flag will be
enabled only after all other features of dynamic shared memory will be
implemented in subsequent patches. Of course user can ignore presence of
TEE_GEN_CAP_REG_MEM flag and try do call those functions. This is okay,
driver will register shared buffer in OP-TEE, but any attempts to use
this shared buffer will fail.

Signed-off-by: Volodymyr Babchuk <vlad.babchuk at gmail.com>
---
 * Extended commit message. Now it describes what will happen if user
   will call optee_shm_register() exactly at this patch (without next ones)

 * Added comment that describesx desctibe why we abuse least bits of
   msg_arg->params->u.tmem.buf_ptr
---
 drivers/tee/optee/call.c          | 69 +++++++++++++++++++++++++++++++++++++++
 drivers/tee/optee/core.c          |  2 ++
 drivers/tee/optee/optee_private.h |  4 +++
 3 files changed, 75 insertions(+)

diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
index 4873666..a22f5f0 100644
--- a/drivers/tee/optee/call.c
+++ b/drivers/tee/optee/call.c
@@ -533,3 +533,72 @@ void optee_free_pages_list(void *array, size_t num_entries)
 	free_pages_exact(array, get_pages_list_size(num_entries));
 }
 
+int optee_shm_register(struct tee_context *ctx, struct tee_shm *shm,
+		       struct page **pages, size_t num_pages)
+{
+	struct tee_shm *shm_arg = NULL;
+	struct optee_msg_arg *msg_arg;
+	u64 *pages_list;
+	phys_addr_t msg_parg;
+	int rc = 0;
+
+	if (!num_pages)
+		return -EINVAL;
+
+	pages_list = optee_allocate_pages_list(num_pages);
+	if (!pages_list)
+		return -ENOMEM;
+
+	shm_arg = get_msg_arg(ctx, 1, &msg_arg, &msg_parg);
+	if (IS_ERR(shm_arg)) {
+		rc = PTR_ERR(shm_arg);
+		goto out;
+	}
+
+	optee_fill_pages_list(pages_list, pages, num_pages,
+			      tee_shm_get_page_offset(shm));
+
+	msg_arg->cmd = OPTEE_MSG_CMD_REGISTER_SHM;
+	msg_arg->params->attr = OPTEE_MSG_ATTR_TYPE_TMEM_OUTPUT |
+				OPTEE_MSG_ATTR_NONCONTIG;
+	msg_arg->params->u.tmem.shm_ref = (unsigned long)shm;
+	msg_arg->params->u.tmem.size = tee_shm_get_size(shm);
+	/*
+	 * In the least bits of msg_arg->params->u.tmem.buf_ptr we
+	 * store buffer offset from 4k page, as described in OP-TEE ABI.
+	 */
+	msg_arg->params->u.tmem.buf_ptr = virt_to_phys(pages_list) |
+	  (tee_shm_get_page_offset(shm) & (OPTEE_MSG_NONCONTIG_PAGE_SIZE - 1));
+
+	if (optee_do_call_with_arg(ctx, msg_parg) ||
+	    msg_arg->ret != TEEC_SUCCESS)
+		rc = -EINVAL;
+
+	tee_shm_free(shm_arg);
+out:
+	optee_free_pages_list(pages_list, num_pages);
+	return rc;
+}
+
+int optee_shm_unregister(struct tee_context *ctx, struct tee_shm *shm)
+{
+	struct tee_shm *shm_arg;
+	struct optee_msg_arg *msg_arg;
+	phys_addr_t msg_parg;
+	int rc = 0;
+
+	shm_arg = get_msg_arg(ctx, 1, &msg_arg, &msg_parg);
+	if (IS_ERR(shm_arg))
+		return PTR_ERR(shm_arg);
+
+	msg_arg->cmd = OPTEE_MSG_CMD_UNREGISTER_SHM;
+
+	msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_RMEM_INPUT;
+	msg_arg->params[0].u.rmem.shm_ref = (unsigned long)shm;
+
+	if (optee_do_call_with_arg(ctx, msg_parg) ||
+	    msg_arg->ret != TEEC_SUCCESS)
+		rc = -EINVAL;
+	tee_shm_free(shm_arg);
+	return rc;
+}
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index 7952357..4d448bf 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -267,6 +267,8 @@ static const struct tee_driver_ops optee_ops = {
 	.close_session = optee_close_session,
 	.invoke_func = optee_invoke_func,
 	.cancel_req = optee_cancel_req,
+	.shm_register = optee_shm_register,
+	.shm_unregister = optee_shm_unregister,
 };
 
 static const struct tee_desc optee_desc = {
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index b63213d..d7bc77d 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -160,6 +160,10 @@ int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session);
 void optee_enable_shm_cache(struct optee *optee);
 void optee_disable_shm_cache(struct optee *optee);
 
+int optee_shm_register(struct tee_context *ctx, struct tee_shm *shm,
+		       struct page **pages, size_t num_pages);
+int optee_shm_unregister(struct tee_context *ctx, struct tee_shm *shm);
+
 int optee_from_msg_param(struct tee_param *params, size_t num_params,
 			 const struct optee_msg_param *msg_params);
 int optee_to_msg_param(struct optee_msg_param *msg_params, size_t num_params,
-- 
2.7.4