Re: [PATCH v14 05/44] arm64: RMI: Add wrappers for RMI calls

[Gavin Shan]

Hi Steven,

On 5/13/26 11:17 PM, Steven Price wrote:
> The wrappers make the call sites easier to read and deal with the
> boiler plate of handling the error codes from the RMM.
>
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> Changes from v13:
>   * Update to RMM v2.0-bet1 spec including some SRO support (there still
>     some FIXMEs where SRO support is incomplete).
> Changes from v12:
>   * Update to RMM v2.0 specification
> Changes from v8:
>   * Switch from arm_smccc_1_2_smc() to arm_smccc_1_2_invoke() in
>     rmi_rtt_read_entry() for consistency.
> Changes from v7:
>   * Minor renaming of parameters and updated comments
> Changes from v5:
>   * Further improve comments
> Changes from v4:
>   * Improve comments
> Changes from v2:
>   * Make output arguments optional.
>   * Mask RIPAS value rmi_rtt_read_entry()
>   * Drop unused rmi_rtt_get_phys()
> ---
>   arch/arm64/include/asm/rmi_cmds.h | 661 ++++++++++++++++++++++++++++++
>   1 file changed, 661 insertions(+)
>   create mode 100644 arch/arm64/include/asm/rmi_cmds.h
>
> diff --git a/arch/arm64/include/asm/rmi_cmds.h b/arch/arm64/include/asm/rmi_cmds.h
> new file mode 100644
> index 000000000000..04f7066894e9
> --- /dev/null
> +++ b/arch/arm64/include/asm/rmi_cmds.h
> @@ -0,0 +1,661 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2023 ARM Ltd.
> + */
> +
> +#ifndef __ASM_RMI_CMDS_H
> +#define __ASM_RMI_CMDS_H
> +
> +#include <linux/arm-smccc.h>
> +

[...]

> +
> +/**
> + * rmi_rtt_destroy() - Destroy an RTT
> + * @rd: PA of the RD
> + * @ipa: Base of the IPA range described by the RTT
> + * @level: Depth of the RTT within the tree
> + * @out_rtt: Pointer to write the PA of the RTT which was destroyed
> + * @out_top: Pointer to write the top IPA of non-live RTT entries
> + *

In most cases, the parameters are well explained in RMM-v2.0-bet1 spec, I think
it's nice to keep the code and the spec synchronized. For those specific parameters
of this function, they're well explained in RMM-v2.0-bet1 spec as below.

   @rd: PA of the RD for the target realm
   @ipa: Base of the IPA range described by the RTT
   @level: RTT level
   @out_rtt: PA of the RTT which was destroyed
   @out_top: Top IPA of non-live RTT entries, from entry at which the RTT walk terminated

> + * Destroys an RTT. The RTT must be non-live, i.e. none of the entries in the
> + * table are in ASSIGNED or TABLE state.
> + *
> + * Return: RMI return code.
> + */
> +static inline int rmi_rtt_destroy(unsigned long rd,
> +				  unsigned long ipa,
> +				  long level,
> +				  unsigned long *out_rtt,
> +				  unsigned long *out_top)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_1_1_invoke(SMC_RMI_RTT_DESTROY, rd, ipa, level, &res);
> +
> +	if (out_rtt)
> +		*out_rtt = res.a1;
> +	if (out_top)
> +		*out_top = res.a2;
> +
> +	return res.a0;
> +}
> +

[...]

Thanks,
Gavin