linux-kernel - Re: [PATCH v3 1/7] firmware: smccc: Add HAVE_ARM_SMCCC_DISCOVERY to identify SMCCC v1.1 and above

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Message-ID: <20200515113727.GA67718@C02TD0UTHF1T.local>
Date:   Fri, 15 May 2020 12:37:27 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Steven Price <steven.price@....com>,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        harb@...erecomputing.com
Subject: Re: [PATCH v3 1/7] firmware: smccc: Add HAVE_ARM_SMCCC_DISCOVERY to
 identify SMCCC v1.1 and above

On Wed, May 06, 2020 at 05:44:05PM +0100, Sudeep Holla wrote:
> SMCCC v1.0 lacked discoverability of version and features. To accelerate
> adoption of few mitigations and protect systems more rapidly from various
> vulnerability, PSCI v1.0 was updated to add SMCCC discovery mechanism
> though the PSCI firmware implementation of PSCI_FEATURES(SMCCC_VERSION)
> which returns success on firmware compliant to SMCCC v1.1 and above.
> 
> This inturn makes SMCCC v1.1 and above dependent on ARM_PSCI_FW for
> backward compatibility. Let us introduce a new hidden config for the
> same to build more features on top of SMCCC v1.1 and above.
> 
> While at it, also sort alphabetically the psci entry.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>

Acked-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.

> ---
>  drivers/firmware/Kconfig       |  6 ++----
>  drivers/firmware/smccc/Kconfig | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+), 4 deletions(-)
>  create mode 100644 drivers/firmware/smccc/Kconfig
> 
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index 8007d4aa76dc..4843e94713a4 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -295,15 +295,13 @@ config TURRIS_MOX_RWTM
>  	  other manufacturing data and also utilize the Entropy Bit Generator
>  	  for hardware random number generation.
>  
> -config HAVE_ARM_SMCCC
> -	bool
> -
> -source "drivers/firmware/psci/Kconfig"
>  source "drivers/firmware/broadcom/Kconfig"
>  source "drivers/firmware/google/Kconfig"
>  source "drivers/firmware/efi/Kconfig"
>  source "drivers/firmware/imx/Kconfig"
>  source "drivers/firmware/meson/Kconfig"
> +source "drivers/firmware/psci/Kconfig"
> +source "drivers/firmware/smccc/Kconfig"
>  source "drivers/firmware/tegra/Kconfig"
>  source "drivers/firmware/xilinx/Kconfig"
>  
> diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
> new file mode 100644
> index 000000000000..d93f1ab52cb2
> --- /dev/null
> +++ b/drivers/firmware/smccc/Kconfig
> @@ -0,0 +1,17 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config HAVE_ARM_SMCCC
> +	bool
> +	help
> +	  Include support for the Secure Monitor Call (SMC) and Hypervisor
> +	  Call (HVC) instructions on Armv7 and above architectures.
> +
> +config HAVE_ARM_SMCCC_DISCOVERY
> +	bool
> +	depends on ARM_PSCI_FW
> +	default y
> +	help
> +	 SMCCC v1.0 lacked discoverability and hence PSCI v1.0 was updated
> +	 to add SMCCC discovery mechanism though the PSCI firmware
> +	 implementation of PSCI_FEATURES(SMCCC_VERSION) which returns
> +	 success on firmware compliant to SMCCC v1.1 and above.
> +
> -- 
> 2.17.1
>