[PATCH] drivers: psci: make PSCI 1.0 functions initialization version dependent

[Kevin Hilman]

On Fri, Oct 23, 2015 at 8:21 AM, Kevin Hilman <khilman at kernel.org> wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi at arm.com> writes:
>
>> The PSCI specifications [1] and the SMC calling convention mandate
>> that unimplemented functions ids must return NOT_SUPPORTED (0xffffffff)
>> if a function id is called but it is not implemented.
>>
>> Consequently, PSCI 1.0 function ids that require the 1.0 PSCI_FEATURES
>> call to be initialized:
>>
>> CPU_SUSPEND (psci_init_cpu_suspend())
>> SYSTEM_SUSPEND (psci_init_system_suspend())
>>
>> call the PSCI_FEATURES function id independently of the detected
>> PSCI firmware version, since, if the PSCI_FEATURES function id is not
>> implemented, it must return NOT_SUPPORTED according to the PSCI
>> specifications, causing the initialization functions to fail as expected.
>>
>> Some existing PSCI implementations (ie Qemu PSCI emulation), do not
>> comply with the SMC calling convention and fail if function ids that are
>> not implemented are called from the OS, causing boot failures.
>>
>> To solve this issue, this patch adds code that checks the PSCI firmware
>> version before calling PSCI 1.0 initialization functions so that the
>> OS makes sure that it is calling 1.0 functions only if the firmware
>> version detected is 1.0 or greater, therefore avoiding PSCI calls
>> that are bound to fail and might cause system boot failures owing
>> to non-compliant PSCI firmware implementations.
>>
>> [1] http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
>>
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
>> Cc: Arnd Bergmann <arnd at arndb.de>
>> Cc: Kevin Hilman <khilman at kernel.org>
>> Cc: Sudeep Holla <sudeep.holla at arm.com>
>> Cc: Olof Johansson <olof at lixom.net>
>> Cc: Mark Rutland <mark.rutland at arm.com>
>> ---
>> Arnd, Kevin, Olof,
>>
>> this applies to current arm-soc drivers/psci branch, and solves the
>> issue Kevin detected through kernelci with Qemu emulation:
>>
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/380304.html
>>
>> Tested on:
>>
>> - Juno host
>> - AMD Seattle host
>> - kvmtool arm64 guest (on Juno arm64 defconfig host)
>> - Qemu x86 host (aarch64 emulation)
>>
>> A run on kernelci and consequent tested-by tags would be much appreciated,
>> thanks for spotting this and for your help.
>
> I tested manually on my local qemu that was failing without this patch,
> and it works:
>
> Tested-by: Kevin Hilman <khilman at linaro.org>
>
> We'll add this onto arm-soc drivers/psci and then it will have a spin through
> kernelci.

FYI... This has now been merged into arm-soc/for-next and had a spin
through kernelci.org, and the arm64 qemu results are passing:
http://kernelci.org/boot/all/job/arm-soc/kernel/v4.3-rc5-571-g9b588fdb667c/

Thanks,

Kevin