Re: Security Random Number Generator support

From: Marc Zyngier
Date: Wed Jun 03 2020 - 07:12:10 EST


On 2020-06-03 08:54, Neal Liu wrote:
On Wed, 2020-06-03 at 08:40 +0100, Marc Zyngier wrote:
On 2020-06-03 08:29, Neal Liu wrote:

[...]

> Could you give us a hint how to make this SMC interface more generic in
> addition to my approach?
> There is no (easy) way to get platform-independent SMC function ID,
> which is why we encode it into device tree, and provide a generic
> driver. In this way, different devices can be mapped and then get
> different function ID internally.

The idea is simply to have *one* single ID that caters for all
implementations, just like we did for PSCI at the time. This
requires ARM to edict a standard, which is what I was referring
to above.

There is zero benefit in having a platform-dependent ID. It just
pointlessly increases complexity, and means we cannot use the RNG
before the firmware tables are available (yes, we need it that
early).

M.

Do you know which ARM expert could edict this standard?
Or is there any chance that we can make one? And be reviewed by
maintainers?

Sudeep already mentioned Jose's effort to offer a standard.
Hopefully he will *soon* be able to give us something that can be
implemented everywhere (firmware, kernel, but also hypervisors),
as the need exists across the whole stack.

M.
--
Jazz is not dead. It just smells funny...