linux-kernel - Re: [PATCH v3 08/12] KVM: arm/arm64: Check vcpu redist base before registering an iodev

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Message-ID: <20180424210759.GI4533@C02W217FHV2R.local>
Date:   Tue, 24 Apr 2018 23:07:59 +0200
From:   Christoffer Dall <christoffer.dall@....com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        marc.zyngier@....com, cdall@...nel.org, peter.maydell@...aro.org,
        andre.przywara@....com, drjones@...hat.com, wei@...hat.com
Subject: Re: [PATCH v3 08/12] KVM: arm/arm64: Check vcpu redist base before
 registering an iodev

On Fri, Apr 13, 2018 at 10:20:54AM +0200, Eric Auger wrote:
> As we are going to register several redist regions,
> vgic_register_all_redist_iodevs() may be called several times. We need
> to register a redist_iodev for a given vcpu only once. 

Wouldn't it be more natural to change that caller to only register the
iodevs for that region?

Thanks,
-Christoffer

> So let's
> check if the base address has already been set. Initialize this latter
> in kvm_vgic_vcpu_early_init().
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> ---
>  virt/kvm/arm/vgic/vgic-init.c    | 3 +++
>  virt/kvm/arm/vgic/vgic-mmio-v3.c | 3 +++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 6456371..7e040e7 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -82,6 +82,9 @@ void kvm_vgic_vcpu_early_init(struct kvm_vcpu *vcpu)
>  	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
>  	spin_lock_init(&vgic_cpu->ap_list_lock);
>  
> +	vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
> +	vgic_cpu->sgi_iodev.base_addr = VGIC_ADDR_UNDEF;
> +
>  	/*
>  	 * Enable and configure all SGIs to be edge-triggered and
>  	 * configure all PPIs as level-triggered.
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index 5273fb8..df23e66 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -592,6 +592,9 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
>  	gpa_t rd_base, sgi_base;
>  	int ret;
>  
> +	if (!IS_VGIC_ADDR_UNDEF(vgic_cpu->rd_iodev.base_addr))
> +		return 0;
> +
>  	/*
>  	 * We may be creating VCPUs before having set the base address for the
>  	 * redistributor region, in which case we will come back to this
> -- 
> 2.5.5
>