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Message-ID: <55b704b7-0a44-8f34-e22f-d60b58db610f@arm.com>
Date:   Fri, 4 Nov 2022 09:13:14 +0000
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Subject: Re: [PATCH] arm64: paravirt: remove conduit check in
 has_pv_steal_clock
To:     Usama Arif <usama.arif@bytedance.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, linux@armlinux.org.uk,
        yezengruan@huawei.com, catalin.marinas@arm.com, will@kernel.org,
        maz@kernel.org, mark.rutland@arm.com
Cc:     fam.zheng@bytedance.com, liangma@liangbit.com,
        punit.agrawal@bytedance.com
References: <20221104061659.4116508-1-usama.arif@bytedance.com>
Content-Language: en-GB
From:   Steven Price <steven.price@arm.com>
In-Reply-To: <20221104061659.4116508-1-usama.arif@bytedance.com>
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On 04/11/2022 06:16, Usama Arif wrote:
> arm_smccc_1_1_invoke() which is called later on in the function
> will return failure if there's no conduit (or pre-SMCCC 1.1),
> hence the check is unnecessary.
> 
> Suggested-by: Steven Price <steven.price@arm.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
>  arch/arm64/kernel/paravirt.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index 57c7c211f8c7..aa718d6a9274 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -141,10 +141,6 @@ static bool __init has_pv_steal_clock(void)
>  {
>  	struct arm_smccc_res res;
>  
> -	/* To detect the presence of PV time support we require SMCCC 1.1+ */
> -	if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
> -		return false;
> -
>  	arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
>  			     ARM_SMCCC_HV_PV_TIME_FEATURES, &res);
>