Re: [PATCH v5 3/9] xen/arm: add a primitive FF-A mediator

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Jens,

On 18/08/2022 12:55, Jens Wiklander wrote:
> Adds a FF-A version 1.1 [1] mediator to communicate with a Secure
> Partition in secure world.
> 
> This commit brings in only the parts needed to negotiate FF-A version
> number with guest and SPMC.
> 
> A guest configuration variable "ffa_enabled" is used to indicate if a guest
> is trusted to use FF-A.
> 
> This is loosely based on the TEE mediator framework and the OP-TEE
> mediator.
> 
> [1] https://developer.arm.com/documentation/den0077/latest
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> ---
>  SUPPORT.md                        |   7 +
>  docs/man/xl.cfg.5.pod.in          |  15 ++
>  tools/include/libxl.h             |   6 +
>  tools/libs/light/libxl_arm.c      |   3 +
>  tools/libs/light/libxl_types.idl  |   1 +
>  tools/xl/xl_parse.c               |   3 +
>  xen/arch/arm/Kconfig              |  11 +
>  xen/arch/arm/Makefile             |   1 +
>  xen/arch/arm/domain.c             |  10 +
>  xen/arch/arm/domain_build.c       |   1 +
>  xen/arch/arm/ffa.c                | 354 ++++++++++++++++++++++++++++++
>  xen/arch/arm/include/asm/domain.h |   4 +
>  xen/arch/arm/include/asm/ffa.h    |  71 ++++++
>  xen/arch/arm/vsmc.c               |  17 +-
>  xen/include/public/arch-arm.h     |   2 +
>  15 files changed, 503 insertions(+), 3 deletions(-)
>  create mode 100644 xen/arch/arm/ffa.c
>  create mode 100644 xen/arch/arm/include/asm/ffa.h
> 
> diff --git a/SUPPORT.md b/SUPPORT.md
> index 70e98964cbc0..215bb3c9043b 100644
> --- a/SUPPORT.md
> +++ b/SUPPORT.md
> @@ -785,6 +785,13 @@ that covers the DMA of the device to be passed through.
>  
>  No support for QEMU backends in a 16K or 64K domain.
>  
> +### ARM: Firmware Framework for Arm A-profile (FF-A) Mediator
> +
> +    Status, Arm64: Tech Preview
> +
> +There are still some code paths where a vCPU may hog a pCPU longer than
> +necessary. The FF-A mediator is not yet implemented for Arm32.
> +
>  ### ARM: Guest Device Tree support
>  
>      Status: Supported
> diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
> index b98d1613987e..234c036aecb1 100644
> --- a/docs/man/xl.cfg.5.pod.in
> +++ b/docs/man/xl.cfg.5.pod.in
> @@ -1616,6 +1616,21 @@ This feature is a B<technology preview>.
>  
>  =back
>  
> +=item B<ffa_enabled=BOOLEAN>
Looking at other config options, we usually have <feature>=BOOLEAN (without 
_enabled), so
I would just stick to "ffa". This would require changes in other places 
accordingly.

> +
> +B<Arm only.> Allow a guest to communicate via FF-A with Secure Partitions
> +(SP), default false.
> +
> +Currently is only a small subset of the FF-A specification supported. Just
Should be:
"Currently only a small subset of the FF-A specification is supported"

> +enough to communicate with OP-TEE. In general all the basic things and
"basic things" sounds a bit ambiguous.

> diff --git a/tools/libs/light/libxl_types.idl 
> b/tools/libs/light/libxl_types.idl
> index 2a42da2f7d78..bf4544bef399 100644
> --- a/tools/libs/light/libxl_types.idl
> +++ b/tools/libs/light/libxl_types.idl
> @@ -646,6 +646,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
Applying this patch results in a failure here so you need to rebase it on top 
of latest status.

Also, FWICS (can be checked by the toolstack maintainers) you are missing the 
required
changes in:
 - tools/golang/xenlight/helpers.gen.go
 - tools/golang/xenlight/types.gen.go
 - tools/ocaml/libs/xc/xenctrl.ml
 - tools/ocaml/libs/xc/xenctrl.mli

~Michal