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

[icenowy at aosc.io]

在 2017-06-07 20:51，Marc Zyngier 写道：
> On 07/06/17 13:12, Icenowy Zheng wrote:
>> 
>> 
>> 于 2017年6月7日 GMT+08:00 下午8:11:12, Marc Zyngier <marc.zyngier at arm.com> 
>> 写到:
>>> 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?
>> 
>> Write Secure Boot eFUSE, which will break *all* existing softwares.
> 
> Don't do it, then.
> 
> Any other *real* use case for running non-secure? As in "Stuff that
> would benefit to a user"? Because if the answer is "none" as I suspect
> it is, you might as well keep the system in secure mode.

Maybe we should then use legacy SMP bringup method (code in kernel)
rather than PSCI?

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