[PATCH v2 03/11] arm64: gunyah: Add Gunyah hypercalls ABI

[Elliot Berman]

Hi Dmitry,

On 8/2/2022 6:34 AM, Dmitry Baryshkov wrote:
> On 02/08/2022 00:12, Elliot Berman wrote:
>> Add initial support to perform Gunyah hypercalls. The arm64 ABI for
>> Gunyah hypercalls generally follows the SMC Calling Convention.
> 
> Seeing a c&p (or c&rework) from arm-smccc.h, could you please describe:
> 
> 1) Why can't you use the existing arm_smccc_1_1_hvc()? I checked, you 
> don't seem to be getting more than 4 values back.
> 

The Gunyah APIs can return up to 8 values. As you observed though, these 
initial patches are only using the first 4 values back. I'd like to use 
the larger v1.2 so I don't need to update later.

> 2) If #1 is not possible, why can't you add necessary glue code to the 
> arm-smccc.h (as your code to support nargs/multiple return values is 
> generic enough) and use corresponding macro in asm/gunyah.h ?
> 

I think the code here may be considered Gunyah-specific as I am limiting 
to 8 arguments and return values. If I add to arm-smccc.h, I would need 
to expand out to x17. Does it make sense to add another SMCCC 1.2 
interface to arm-smccc.h?