Merge tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee into next/drivers

Pull "tee dynamic shm for v4.16" from Jens Wiklander:

This pull request enables dynamic shared memory support in the TEE
subsystem as a whole and in OP-TEE in particular.

Global Platform TEE specification [1] allows client applications
to register part of own memory as a shared buffer between
application and TEE. This allows fast zero-copy communication between
TEE and REE. But current implementation of TEE in Linux does not support
this feature.

Also, current implementation of OP-TEE transport uses fixed size
pre-shared buffer for all communications with OP-TEE OS. This is okay
in the most use cases. But this prevents use of OP-TEE in virtualized
environments, because:
 a) We can't share the same buffer between different virtual machines
 b) Physically contiguous memory as seen by VM can be non-contiguous
    in reality (and as seen by OP-TEE OS) due to second stage of
    MMU translation.
 c) Size of this pre-shared buffer is limited.

So, first part of this pull request adds generic register/unregister
interface to tee subsystem. The second part adds necessary features into
OP-TEE driver, so it can use not only static pre-shared buffer, but
whole RAM to communicate with OP-TEE OS.

This change is backwards compatible allowing older secure world or
user space to work with newer kernels and vice versa.

[1] https://www.globalplatform.org/specificationsdevice.asp

* tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee:
  tee: shm: inline tee_shm_get_id()
  tee: use reference counting for tee_context
  tee: optee: enable dynamic SHM support
  tee: optee: add optee-specific shared pool implementation
  tee: optee: store OP-TEE capabilities in private data
  tee: optee: add registered buffers handling into RPC calls
  tee: optee: add registered shared parameters handling
  tee: optee: add shared buffer registration functions
  tee: optee: add page list manipulation functions
  tee: optee: Update protocol definitions
  tee: shm: add page accessor functions
  tee: shm: add accessors for buffer size and page offset
  tee: add register user memory
  tee: flexible shared memory pool creation

1 files changed, 32 insertions, 6 deletions

diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
index dd7a06ee0462..30504901be80 100644
--- a/drivers/tee/optee/optee_msg.h
+++ b/drivers/tee/optee/optee_msg.h
@@ -67,11 +67,32 @@
 #define OPTEE_MSG_ATTR_META			BIT(8)
 
 /*
- * The temporary shared memory object is not physically contigous and this
- * temp memref is followed by another fragment until the last temp memref
- * that doesn't have this bit set.
+ * Pointer to a list of pages used to register user-defined SHM buffer.
+ * Used with OPTEE_MSG_ATTR_TYPE_TMEM_*.
+ * buf_ptr should point to the beginning of the buffer. Buffer will contain
+ * list of page addresses. OP-TEE core can reconstruct contiguous buffer from
+ * that page addresses list. Page addresses are stored as 64 bit values.
+ * Last entry on a page should point to the next page of buffer.
+ * Every entry in buffer should point to a 4k page beginning (12 least
+ * significant bits must be equal to zero).
+ *
+ * 12 least significant bints of optee_msg_param.u.tmem.buf_ptr should hold page
+ * offset of the user buffer.
+ *
+ * So, entries should be placed like members of this structure:
+ *
+ * struct page_data {
+ *   uint64_t pages_array[OPTEE_MSG_NONCONTIG_PAGE_SIZE/sizeof(uint64_t) - 1];
+ *   uint64_t next_page_data;
+ * };
+ *
+ * Structure is designed to exactly fit into the page size
+ * OPTEE_MSG_NONCONTIG_PAGE_SIZE which is a standard 4KB page.
+ *
+ * The size of 4KB is chosen because this is the smallest page size for ARM
+ * architectures. If REE uses larger pages, it should divide them to 4KB ones.
  */
-#define OPTEE_MSG_ATTR_FRAGMENT			BIT(9)
+#define OPTEE_MSG_ATTR_NONCONTIG		BIT(9)
 
 /*
  * Memory attributes for caching passed with temp memrefs. The actual value
@@ -94,6 +115,11 @@
 #define OPTEE_MSG_LOGIN_APPLICATION_USER	0x00000005
 #define OPTEE_MSG_LOGIN_APPLICATION_GROUP	0x00000006
 
+/*
+ * Page size used in non-contiguous buffer entries
+ */
+#define OPTEE_MSG_NONCONTIG_PAGE_SIZE		4096
+
 /**
  * struct optee_msg_param_tmem - temporary memory reference parameter
  * @buf_ptr:	Address of the buffer
@@ -145,8 +171,8 @@ struct optee_msg_param_value {
  *
  * @attr & OPTEE_MSG_ATTR_TYPE_MASK indicates if tmem, rmem or value is used in
  * the union. OPTEE_MSG_ATTR_TYPE_VALUE_* indicates value,
- * OPTEE_MSG_ATTR_TYPE_TMEM_* indicates tmem and
- * OPTEE_MSG_ATTR_TYPE_RMEM_* indicates rmem.
+ * OPTEE_MSG_ATTR_TYPE_TMEM_* indicates @tmem and
+ * OPTEE_MSG_ATTR_TYPE_RMEM_* indicates @rmem,
  * OPTEE_MSG_ATTR_TYPE_NONE indicates that none of the members are used.
  */
 struct optee_msg_param {