[U-Boot] [linux-sunxi] [RFC PATCH 8/8] sunxi: enable PSCI for A83T SoC

[Marc Zyngier]

On 07/06/17 08:00, Chen-Yu Tsai wrote:
> On Wed, Jun 7, 2017 at 2:50 PM, Maxime Ripard
> <maxime.ripard at free-electrons.com> wrote:
>> On Wed, Jun 07, 2017 at 11:47:24AM +0800, Chen-Yu Tsai wrote:
>>> On Wed, Jun 7, 2017 at 11:40 AM, Icenowy Zheng <icenowy at aosc.io> wrote:
>>>>
>>>>
>>>> 于 2017年6月7日 GMT+08:00 上午11:36:27, Chen-Yu Tsai <wens at csie.org> 写到:
>>>>> On Wed, Jun 7, 2017 at 8:47 AM, Icenowy Zheng <icenowy at aosc.io> wrote:
>>>>>> As we have now a basical implementation of PSCI for A83T, enable
>>>>>> non-secure boot support and PSCI on A83T now.
>>>>>>
>>>>>> Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>>>>>> ---
>>>>>>  arch/arm/mach-sunxi/Kconfig | 4 ++++
>>>>>>  1 file changed, 4 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm/mach-sunxi/Kconfig
>>>>> b/arch/arm/mach-sunxi/Kconfig
>>>>>> index 7ced838d6a..31d29de428 100644
>>>>>> --- a/arch/arm/mach-sunxi/Kconfig
>>>>>> +++ b/arch/arm/mach-sunxi/Kconfig
>>>>>> @@ -98,8 +98,12 @@ config MACH_SUN8I_A33
>>>>>>  config MACH_SUN8I_A83T
>>>>>>         bool "sun8i (Allwinner A83T)"
>>>>>>         select CPU_V7
>>>>>> +       select CPU_V7_HAS_NONSEC
>>>>>> +       select CPU_V7_HAS_VIRT
>>>>>> +       select ARCH_SUPPORT_PSCI
>>>>>>         select SUNXI_GEN_SUN6I
>>>>>>         select SUPPORT_SPL
>>>>>> +       select ARMV7_BOOT_SEC_DEFAULT if OLD_SUNXI_KERNEL_COMPAT
>>>>>
>>>>> The kernel does not work yet. Please have it boot to secure by default
>>>>> regardless of the kernel. We can have it boot non-secure once the
>>>>> kernel
>>>>> has been working for a reasonable amount of time.
>>>>>
>>>>> I don't want clueless users coming and asking why it suddenly stopped
>>>>> working. This should be an experimental feature.
>>>>
>>>> Maybe you should send out the fix, and tag them to also apply to
>>>> stable tree.
>>>>
>>>> GIC is really broken, UP systems only work by chance. We
>>>> shouldn't depend on this behavior.
>>>
>>> As I previously explained, it is not the GIC that is broken. I believe
>>> the GIC is working exactly as it is supposed to with regards to its
>>> input signals.
>>>
>>> Allwinner's security extensions implementation simply does not properly
>>> forward the AXI secure bit when the e-fuse's secure bit isn't burned.

Arghh. Puke. Now I remember this, and I wish I didn't...

>> Is that on all revisions, or just the revB ?
> 
> It's the A80, but I'm guessing the same applies to the A83T. It's more
> of a guess really, but I think it's a logical one. If the e-fuse isn't
> programmed, the TZPC doesn't work, and access to all secure peripherals
> still work, even from non-secure mode. The only one that does work is
> the secure SRAM.
> 
> The GIC still has the banked secure/non-secure registers, just that all
> cores access the secure bank, even when in non-secure mode. The workaround
> is to use the alias set of non-secure registers in Linux.

That's a pretty dire workaround. Also, I expect that secure writes to
GICV/GICH will not do the right thing. At this point, what is the
requirement for running non-secure?

> I'm not about to waste one of my boards programming the e-fuse to find
> out the hard way though. The CCU doesn't have a security setting. It
> might as well be secure-only. If one sets the e-fuse and the SoC's
> security extensions work as they're supposed to, then it will no longer
> work with mainline Linux. Or any software we have for that matter.

Fair enough.

Thanks,

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