Re: [PATCH 4/6] drivers/virt: pkvm: Hook up mem_encrypt API using pKVM hypercalls

[Marc Zyngier <maz@kernel.org>]

On Tue, 30 Jul 2024 16:11:10 +0100,
Will Deacon <will@kernel.org> wrote:
> 
> If we detect the presence of pKVM's SHARE and UNSHARE hypercalls, then
> register a backend implementation of the mem_encrypt API so that things
> like DMA buffers can be shared appropriately with the host.
> 
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  Documentation/virt/kvm/arm/hypercalls.rst     | 50 +++++++++++++++++
>  drivers/virt/coco/pkvm-guest/arm-pkvm-guest.c | 55 +++++++++++++++++++
>  include/linux/arm-smccc.h                     | 14 +++++
>  3 files changed, 119 insertions(+)
> 

[...]

> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 16b6dcc54e02..9cb7c95920b0 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -116,6 +116,8 @@
>  #define ARM_SMCCC_KVM_FUNC_FEATURES		0
>  #define ARM_SMCCC_KVM_FUNC_PTP			1
>  #define ARM_SMCCC_KVM_FUNC_HYP_MEMINFO		2
> +#define ARM_SMCCC_KVM_FUNC_MEM_SHARE		3
> +#define ARM_SMCCC_KVM_FUNC_MEM_UNSHARE		4
>  #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
>  #define ARM_SMCCC_KVM_NUM_FUNCS			128

As you will certainly add a bunch of other calls (hopefully soon-ish),
how about reserving an actual range for those, so that we can
future-proof the ABI early?

Grab 64 right away, and we don't have to worry about new stuff for a
while.

What do you think?

	M.

-- 
Without deviation from the norm, progress is not possible.