linux-kernel - Re: [PATCH v4 01/15] arm64: rsi: Add RSI definitions

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Message-ID: <3b2ddd79-c7f0-4d41-8795-13d1305e3d08@arm.com>
Date: Wed, 10 Jul 2024 16:34:09 +0100
From: Steven Price <steven.price@....com>
To: Gavin Shan <gshan@...hat.com>, kvm@...r.kernel.org, kvmarm@...ts.linux.dev
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
 Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
 Will Deacon <will@...nel.org>, James Morse <james.morse@....com>,
 Oliver Upton <oliver.upton@...ux.dev>, Zenghui Yu <yuzenghui@...wei.com>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Joey Gouly <joey.gouly@....com>, Alexandru Elisei
 <alexandru.elisei@....com>, Christoffer Dall <christoffer.dall@....com>,
 Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
 Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Subject: Re: [PATCH v4 01/15] arm64: rsi: Add RSI definitions

On 09/07/2024 06:19, Gavin Shan wrote:
> On 7/1/24 7:54 PM, Steven Price wrote:
>> From: Suzuki K Poulose <suzuki.poulose@....com>
>>
>> The RMM (Realm Management Monitor) provides functionality that can be
>> accessed by a realm guest through SMC (Realm Services Interface) calls.
>>
>> The SMC definitions are based on DEN0137[1] version A-eac5.
>>
>> [1] https://developer.arm.com/documentation/den0137/latest
>>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>> Signed-off-by: Steven Price <steven.price@....com>
>> ---
>> Changes since v3:
>>   * Drop invoke_rsi_fn_smc_with_res() function and call arm_smccc_smc()
>>     directly instead.
>>   * Rename header guard in rsi_smc.h to be consistent.
>> Changes since v2:
>>   * Rename rsi_get_version() to rsi_request_version()
>>   * Fix size/alignment of struct realm_config
>> ---
>>   arch/arm64/include/asm/rsi_cmds.h |  38 ++++++++
>>   arch/arm64/include/asm/rsi_smc.h  | 142 ++++++++++++++++++++++++++++++
>>   2 files changed, 180 insertions(+)
>>   create mode 100644 arch/arm64/include/asm/rsi_cmds.h
>>   create mode 100644 arch/arm64/include/asm/rsi_smc.h
>>
> 
> [...]
> 
>> --- /dev/null
>> +++ b/arch/arm64/include/asm/rsi_smc.h
>> @@ -0,0 +1,142 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2023 ARM Ltd.
>> + */
>> +
>> +#ifndef __ASM_RSI_SMC_H_
>> +#define __ASM_RSI_SMC_H_
>> +
>> +/*
>> + * This file describes the Realm Services Interface (RSI) Application
>> Binary
>> + * Interface (ABI) for SMC calls made from within the Realm to the
>> RMM and
>> + * serviced by the RMM.
>> + */
>> +
>> +#define SMC_RSI_CALL_BASE        0xC4000000
>> +
> 
> These fields have been defined in include/linux/arm-smccc.h. Those definitions
> can be reused. Otherwise, it's not obvious to reader what does 0xC4000000 represent.
> 
> #define SMC_RSI_CALL_BASE    ((ARM_SMCCC_FAST_CALL << ARM_SMCCC_TYPE_SHIFT)   | \
>                                  (ARM_SMCCC_SMC_64 << ARM_SMCCC_CALL_CONV_SHIFT) | \
>                                  (ARM_SMCCC_OWNER_STANDARD << ARM_SMCCC_OWNER_SHIFT))
> 
> or
> 
> #define SMC_RSI_CALL_BASE       ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,            \
>                                                    ARM_SMCCC_SMC_64,               \
>                                                    ARM_SMCCC_OWNER_STANDARD,       \
>                                                    0)

Good point, even better is actually to just drop SMC_RSI_CALL_BASE and
just redefine SMC_RSI_FID() in terms of ARM_SMCCC_CALL_VAL().

Thanks,
Steve