Re: [PATCH v3 08/17] xen/arm: psci: Detect SMCCC version

From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien.grall@arm.com>
Cc: sstabellini@kernel.org, volodymyr_babchuk@epam.com,
	andre.przywara@linaro.org, xen-devel@lists.xen.org
Subject: Re: [PATCH v3 08/17] xen/arm: psci: Detect SMCCC version
Date: Tue, 20 Feb 2018 16:16:40 -0800 (PST)	[thread overview]
Message-ID: <alpine.DEB.2.10.1802201616200.19448@sstabellini-ThinkPad-X260> (raw)
In-Reply-To: <20180215150248.28922-9-julien.grall@arm.com>

On Thu, 15 Feb 2018, Julien Grall wrote:
> PSCI 1.0 and later allows the SMCCC version to be (indirectly) probed
> via PSCI_FEATURES. If the PSCI_FEATURES does not exist (PSCI 0.2 or
> earlier) and the function return an error, then we considered SMCCC 1.0
> is implemented.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
>     Changes in v2:
>         - Patch added
> ---
>  xen/arch/arm/psci.c         | 34 +++++++++++++++++++++++++++++++++-
>  xen/include/asm-arm/smccc.h |  2 ++
>  2 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
> index 5dda35cd7c..bc7b2260e8 100644
> --- a/xen/arch/arm/psci.c
> +++ b/xen/arch/arm/psci.c
> @@ -37,6 +37,7 @@
>  #endif
>  
>  uint32_t psci_ver;
> +uint32_t smccc_ver;
>  
>  static uint32_t psci_cpu_on_nr;
>  
> @@ -57,6 +58,14 @@ void call_psci_system_reset(void)
>          call_smc(PSCI_0_2_FN32_SYSTEM_RESET, 0, 0, 0);
>  }
>  
> +static int __init psci_features(uint32_t psci_func_id)
> +{
> +    if ( psci_ver < PSCI_VERSION(1, 0) )
> +        return PSCI_NOT_SUPPORTED;
> +
> +    return call_smc(PSCI_1_0_FN32_PSCI_FEATURES, psci_func_id, 0, 0);
> +}
> +
>  int __init psci_is_smc_method(const struct dt_device_node *psci)
>  {
>      int ret;
> @@ -82,6 +91,24 @@ int __init psci_is_smc_method(const struct dt_device_node *psci)
>      return 0;
>  }
>  
> +static void __init psci_init_smccc(void)
> +{
> +    /* PSCI is using at least SMCC 1.0 calling convention. */
> +    smccc_ver = ARM_SMCCC_VERSION_1_0;
> +
> +    if ( psci_features(ARM_SMCCC_VERSION_FID) != PSCI_NOT_SUPPORTED )
> +    {
> +        uint32_t ret;
> +
> +        ret = call_smc(ARM_SMCCC_VERSION_FID, 0, 0, 0);
> +        if ( ret != ARM_SMCCC_NOT_SUPPORTED )
> +            smccc_ver = ret;
> +    }
> +
> +    printk(XENLOG_INFO "Using SMC Calling Convention v%u.%u\n",
> +           SMCCC_VERSION_MAJOR(smccc_ver), SMCCC_VERSION_MINOR(smccc_ver));
> +}
> +
>  int __init psci_init_0_1(void)
>  {
>      int ret;
> @@ -173,7 +200,12 @@ int __init psci_init(void)
>      if ( ret )
>          ret = psci_init_0_1();
>  
> -    return ret;
> +    if ( ret )
> +        return ret;
> +
> +    psci_init_smccc();
> +
> +    return 0;
>  }
>  
>  /*
> diff --git a/xen/include/asm-arm/smccc.h b/xen/include/asm-arm/smccc.h
> index d0240d64bf..bc067892c7 100644
> --- a/xen/include/asm-arm/smccc.h
> +++ b/xen/include/asm-arm/smccc.h
> @@ -52,6 +52,8 @@
>  
>  #ifndef __ASSEMBLY__
>  
> +extern uint32_t smccc_ver;
> +
>  /* Check if this is fast call. */
>  static inline bool smccc_is_fast_call(register_t funcid)
>  {
> -- 
> 2.11.0
> 

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