Re: [PATCH v2 02/15] xen/arm: vpsci: Add support for PSCI 1.1

[Julien Grall <julien.grall@arm.com>]

On 02/09/2018 04:07 PM, Volodymyr Babchuk wrote:
> Hi Julien,

Hi Volodymyr,

> On 08.02.18 21:21, Julien Grall wrote:
>> At the moment, Xen provides virtual PSCI interface compliant with 0.1
>> and 0.2. Since them, the specification has been updated and the latest
>> version is 1.1 (see ARM DEN 0022D).
>>
>>  From an implementation point of view, only PSCI_FEATURES is mandatory.
>> The rest is optional and can be left unimplemented for now.
>>
>> At the same time, the compatible for PSCI node have been updated to
>> expose "arm,psci-1.0".
>>
>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>> Cc: Wei Liu <wei.liu2@citrix.com>
>> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
>> Cc: mirela.simonovic@aggios.com
>>
>> ---
>>      We may want to provide a way for the toolstack to specify a PSCI
>>      version. This could be useful if a guest is expecting a given
>>      version.
>>
>>      Changes in v2:
>>          - Return v1.1 on GET_VERSION call as claimed by this patch
>>          - Order by function ID the calls in FEATURES call
>> ---
>>   tools/libxl/libxl_arm.c          |  3 ++-
>>   xen/arch/arm/domain_build.c      |  1 +
>>   xen/arch/arm/vpsci.c             | 39 
>> ++++++++++++++++++++++++++++++++++++++-
>>   xen/include/asm-arm/perfc_defn.h |  1 +
>>   xen/include/asm-arm/psci.h       |  1 +
>>   xen/include/asm-arm/vpsci.h      |  2 +-
>>   6 files changed, 44 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
>> index 3e46554301..86f59c0d80 100644
>> --- a/tools/libxl/libxl_arm.c
>> +++ b/tools/libxl/libxl_arm.c
>> @@ -410,7 +410,8 @@ static int make_psci_node(libxl__gc *gc, void *fdt)
>>       res = fdt_begin_node(fdt, "psci");
>>       if (res) return res;
>> -    res = fdt_property_compat(gc, fdt, 2, "arm,psci-0.2","arm,psci");
>> +    res = fdt_property_compat(gc, fdt, 3, "arm,psci-1.0",
>> +                              "arm,psci-0.2", "arm,psci");
> What about this place? Should it be "arm,psci-1.1"?

arm,psci-1.1 compatible string does not exist. Technically after 0.2 you 
should discover the PSCI version through GET_VERSION. So I am not 
entirely sure why arm,psci-1.0 compatible was added.

 From the documentation 
(Documentation/devicetree/bindings/arm/psci.txt), the compatibles means 
the PSCI implementation comply to a given version. Our implementation 
complies to 0.1, 0.2 and 1.0. So I have added 1.0 just in case a guest 
decides to check the compatible.

Cheers,

-- 
Julien Grall

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