Re: [PATCH v6 1/6] arm64: smccc: Add support for SMCCCv1.2 extended input/output registers

Hi Michael,

On Wed, May 05, 2021 at 03:28:56PM +0000, Michael Kelley wrote:

From: Sudeep Holla <redacted> Sent: Wednesday, May 5, 2021 2:39 AM

quoted

SMCCC v1.2 allows x8-x17 to be used as parameter registers and x4—x17
to be used as result registers in SMC64/HVC64. Arm Firmware Framework
for Armv8-A specification makes use of x0-x7 as parameter and result
registers. There are other users like Hyper-V who intend to use beyond
x0-x7 as well.

Current SMCCC interface in the kernel just use x0-x7 as parameter and
x0-x3 as result registers as required by SMCCCv1.0. Let us add new
interface to support this extended set of input/output registers namely
x0-x17 as both parameter and result registers.

[...]

I've tested the new arm_smccc_1_2_hvc() function in the context
of Linux guests making hypercalls on Hyper-V for ARM64, and it
works as intended.   But note that my test case only uses X0 thru X7.

Tested-by: Michael Kelley <redacted>
Reviewed-by: Michael Kelley <redacted>

Thanks!

-- 
Regards,
Sudeep

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