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

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

Hi Michal,

On Wed, Aug 24, 2022 at 11:28 AM Michal Orzel <michal.orzel@xxxxxxx> wrote:
>
> 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.

OK, I'll update.

>
> > +
> > +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.

I'll rephrase.

>
> > 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.

OK, I'll rebase the next patchset.

>
> 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

I'll update.

Thanks for the review.

Cheers,
Jens