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
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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

include/uapi/linux/tee.h

@@ -50,6 +50,7 @@
 
 #define TEE_GEN_CAP_GP		(1 << 0)/* GlobalPlatform compliant TEE */
 #define TEE_GEN_CAP_PRIVILEGED	(1 << 1)/* Privileged device (for supplicant) */
+#define TEE_GEN_CAP_REG_MEM	(1 << 2)/* Supports registering shared memory */
 
 /*
  * TEE Implementation ID
@@ -339,6 +340,35 @@ struct tee_iocl_supp_send_arg {
 #define TEE_IOC_SUPPL_SEND	_IOR(TEE_IOC_MAGIC, TEE_IOC_BASE + 7, \
 				     struct tee_ioctl_buf_data)
 
+/**
+ * struct tee_ioctl_shm_register_data - Shared memory register argument
+ * @addr:      [in] Start address of shared memory to register
+ * @length:    [in/out] Length of shared memory to register
+ * @flags:     [in/out] Flags to/from registration.
+ * @id:                [out] Identifier of the shared memory
+ *
+ * The flags field should currently be zero as input. Updated by the call
+ * with actual flags as defined by TEE_IOCTL_SHM_* above.
+ * This structure is used as argument for TEE_IOC_SHM_REGISTER below.
+ */
+struct tee_ioctl_shm_register_data {
+	__u64 addr;
+	__u64 length;
+	__u32 flags;
+	__s32 id;
+};
+
+/**
+ * TEE_IOC_SHM_REGISTER - Register shared memory argument
+ *
+ * Registers shared memory between the user space process and secure OS.
+ *
+ * Returns a file descriptor on success or < 0 on failure
+ *
+ * The shared memory is unregisterred when the descriptor is closed.
+ */
+#define TEE_IOC_SHM_REGISTER   _IOWR(TEE_IOC_MAGIC, TEE_IOC_BASE + 9, \
+				     struct tee_ioctl_shm_register_data)
 /*
  * Five syscalls are used when communicating with the TEE driver.
  * open(): opens the device associated with the driver