linux-kernel - Re: [RFC PATCH v2 04/26] KVM: arm64: Initialize kvm_nvhe_init

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Message-ID: <20210201174143.GB15632@willie-the-truck>
Date:   Mon, 1 Feb 2021 17:41:43 +0000
From:   Will Deacon <will@...nel.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, android-kvm@...gle.com,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        Fuad Tabba <tabba@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        David Brazdil <dbrazdil@...gle.com>
Subject: Re: [RFC PATCH v2 04/26] KVM: arm64: Initialize kvm_nvhe_init_params
 early

On Fri, Jan 08, 2021 at 12:15:02PM +0000, Quentin Perret wrote:
> Move the initialization of kvm_nvhe_init_params in a dedicated function
> that is run early, and only once during KVM init, rather than every time
> the KVM vectors are set and reset.
> 
> This also opens the opportunity for the hypervisor to change the init
> structs during boot, hence simplifying the replacement of host-provided
> page-tables and stacks by the ones the hypervisor will create for
> itself.
> 
> Signed-off-by: Quentin Perret <qperret@...gle.com>
> ---
>  arch/arm64/kvm/arm.c | 28 ++++++++++++++++++++--------
>  1 file changed, 20 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 04c44853b103..3ac0f3425833 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c

[...]

> @@ -1807,6 +1813,12 @@ static int init_hyp_mode(void)
>  			goto out_err;
>  	}
>  
> +	/*
> +	 * Prepare the CPU initialization parameters
> +	 */
> +	for_each_possible_cpu(cpu)
> +		cpu_prepare_hyp_mode(cpu);
> +

This is the fifth for_each_possible_cpu() loop in this function; can any of
them be merged together?

Will