The outcome of the previous RFC about how do secure data path was the need of a secure memory allocator (https://lkml.org/lkml/2015/5/5/551)
SMAF goal is to provide a framework that allow allocating and securing memory by using dma_buf. Each platform have it own way to perform those two features so SMAF design allow to register helper modules to perform them.
To be sure to select the best allocation method for devices SMAF implement deferred allocation mechanism: memory allocation is only done when the first device effectively required it. Allocator modules have to implement a match() to let SMAF know if they are compatibles with devices needs. This patch set provide an example of allocator module which use dma_{alloc/free/mmap}_attrs() and check if at least one device have coherent_dma_mask set to DMA_BIT_MASK(32) in match function. I have named smaf-cma.c like it is done for drm_gem_cma_helper.c even if a better name could be found for this file.
Secure modules are responsibles of granting and revoking devices access rights on the memory. Secure module is also called to check if CPU map memory into kernel and user address spaces. An example of secure module implementation can be found here: http://git.linaro.org/people/benjamin.gaignard/optee-sdp.git This code isn't yet part of the patch set because it depends on generic TEE which is still under discussion (https://lwn.net/Articles/644646/)
For allocation part of SMAF code I get inspirated by Sumit Semwal work about constraint aware allocator.
Benjamin Gaignard (2): create SMAF module SMAF: add CMA allocator
drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/smaf/Kconfig | 11 + drivers/smaf/Makefile | 2 + drivers/smaf/smaf-cma.c | 198 ++++++++++++ drivers/smaf/smaf-core.c | 674 +++++++++++++++++++++++++++++++++++++++++ include/linux/smaf-allocator.h | 43 +++ include/linux/smaf-secure.h | 62 ++++ include/uapi/linux/smaf.h | 48 +++ 9 files changed, 1041 insertions(+) create mode 100644 drivers/smaf/Kconfig create mode 100644 drivers/smaf/Makefile create mode 100644 drivers/smaf/smaf-cma.c create mode 100644 drivers/smaf/smaf-core.c create mode 100644 include/linux/smaf-allocator.h create mode 100644 include/linux/smaf-secure.h create mode 100644 include/uapi/linux/smaf.h