linux-kernel - Re: [PATCH v5 07/43] arm64: RME: Check for RME support at KVM init

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Message-ID: <de82957b-eb1a-48b6-8f34-575045c62ed1@arm.com>
Date: Mon, 7 Oct 2024 11:34:11 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
 kvmarm@...ts.linux.dev
Cc: 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>,
 Gavin Shan <gshan@...hat.com>, Shanker Donthineni <sdonthineni@...dia.com>,
 Alper Gun <alpergun@...gle.com>, "Aneesh Kumar K . V"
 <aneesh.kumar@...nel.org>
Subject: Re: [PATCH v5 07/43] arm64: RME: Check for RME support at KVM init

On 04/10/2024 16:27, Steven Price wrote:
> Query the RMI version number and check if it is a compatible version. A
> static key is also provided to signal that a supported RMM is available.
> 
> Functions are provided to query if a VM or VCPU is a realm (or rec)
> which currently will always return false.
> 
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>

> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
> new file mode 100644
> index 000000000000..418685fbf6ed
> --- /dev/null
> +++ b/arch/arm64/kvm/rme.c
> @@ -0,0 +1,50 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2023 ARM Ltd.
> + */
> +
> +#include <linux/kvm_host.h>
> +
> +#include <asm/rmi_cmds.h>
> +#include <asm/virt.h>
> +
> +static int rmi_check_version(void)
> +{
> +	struct arm_smccc_res res;
> +	int version_major, version_minor;
> +	unsigned long host_version = RMI_ABI_VERSION(RMI_ABI_MAJOR_VERSION,
> +						     RMI_ABI_MINOR_VERSION);
> +
> +	arm_smccc_1_1_invoke(SMC_RMI_VERSION, host_version, &res);
> +
> +	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> +		return -ENXIO;
> +
> +	version_major = RMI_ABI_VERSION_GET_MAJOR(res.a1);
> +	version_minor = RMI_ABI_VERSION_GET_MINOR(res.a1);
> +
> +	if (res.a0 != RMI_SUCCESS) {
> +		kvm_err("Unsupported RMI ABI (v%d.%d) host supports v%d.%d\n",

minor nit: s/host supports/we want ? (or something similar)

"host" could be confusing from a user perspective ?

Rest looks good to me

Suzuki