On Fri, Oct 02, 2026 at 02:57:20PM -0700, Kameron Carr wrote:
> Add struct rsi_host_call to arm-smccc-rsi.h, which represents the host
> call data structure used by the Realm Management Monitor (RMM) for the
> RSI_HOST_CALL interface. The structure contains a 16-bit immediate field
> and 31 general-purpose register values, aligned to 256 bytes as required
> by the CCA RMM specification.
>
> Add rsi_host_call() static inline wrapper in arm-rsi-cmds.h that invokes
> SMC_RSI_HOST_CALL with the physical address of the host call structure.
> This will be used by Hyper-V guest code to route hypercalls through the
> RSI interface when running inside an Arm CCA Realm.
>
> Reviewed-by: Michael Kelley <[email protected]>
> Signed-off-by: Kameron Carr <[email protected]>
> ---
> include/linux/arm-rsi-cmds.h | 22 ++++++++++++++++++++++
> include/linux/arm-smccc-rsi.h | 7 +++++++
ARM maintainers, I think this needs an ack from you?
Wei
> 2 files changed, 29 insertions(+)
>
> diff --git a/include/linux/arm-rsi-cmds.h b/include/linux/arm-rsi-cmds.h
> index 3f7a6a8..01d292e 100644
> --- a/include/linux/arm-rsi-cmds.h
> +++ b/include/linux/arm-rsi-cmds.h
> @@ -236,4 +236,26 @@ static inline unsigned long
> rsi_attestation_token_continue(phys_addr_t granule,
> return res.a0;
> }
>
> +/**
> + * rsi_host_call - Make a Host call.
> + * @host_call_struct: IPA of host call structure
> + *
> + * This call will fail if the IPA of the host call structure:
> + * * is not aligned to 256 bytes,
> + * * is not protected / encrypted,
> + * * is RIPAS_EMPTY
> + *
> + * Returns:
> + * On success, returns RSI_SUCCESS.
> + * Otherwise, returns an error code.
> + */
> +static inline unsigned long rsi_host_call(phys_addr_t host_call_struct)
> +{
> + struct arm_smccc_res res;
> +
> + arm_smccc_smc(SMC_RSI_HOST_CALL, host_call_struct, 0, 0, 0, 0, 0, 0,
> + &res);
> + return res.a0;
> +}
> +
> #endif /* __LINUX_ARM_RSI_CMDS_H_ */
> diff --git a/include/linux/arm-smccc-rsi.h b/include/linux/arm-smccc-rsi.h
> index fddb779..4c8530b 100644
> --- a/include/linux/arm-smccc-rsi.h
> +++ b/include/linux/arm-smccc-rsi.h
> @@ -142,6 +142,13 @@ struct realm_config {
> */
> } __aligned(0x1000);
>
> +struct rsi_host_call {
> + u16 immediate;
> + u8 _padding[6];
> + u64 gprs[31];
> +} __aligned(256);
> +static_assert(sizeof(struct rsi_host_call) == 256);
> +
> #endif /* __ASSEMBLER__ */
>
> /*
> --
> 2.45.4
>
