Re: [PATCH v2 4/5] xen/domain: Allocate d->vcpu[] earlier during domain_create()

From: Julien Grall <julien.grall@arm.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH v2 4/5] xen/domain: Allocate d->vcpu[] earlier during domain_create()
Date: Wed, 14 Nov 2018 18:59:05 +0000	[thread overview]
Message-ID: <5decbe62-8030-bf8e-117c-bc1874a90d31@arm.com> (raw)
In-Reply-To: <1542039391-32406-5-git-send-email-andrew.cooper3@citrix.com>

Hi Andrew,

On 12/11/2018 16:16, Andrew Cooper wrote:
> The ARM code has a chicken-and-egg problem.  One of the vGIC_v3 emulations

NIT: s/vGIC_v3/vGICv3/

> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index 5a4f082..892445e 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -667,9 +667,27 @@ void vgic_free_virq(struct domain *d, unsigned int virq)
>       clear_bit(virq, d->arch.vgic.allocated_irqs);
>   }
>   
> -unsigned int vgic_max_vcpus(const struct domain *d)
> +unsigned int vgic_max_vcpus(unsigned int domctl_vgic_version)
>   {
> -    return min_t(unsigned int, MAX_VIRT_CPUS, d->arch.vgic.handler->max_vcpus);
> +    unsigned int max_vcpus;
> +
> +    switch ( domctl_vgic_version )
> +    {
> +    case XEN_DOMCTL_CONFIG_GIC_V2:
> +        max_vcpus = 8;
> +        break;
> +
> +#ifdef CONFIG_GICV3
> +    case XEN_DOMCTL_CONFIG_GIC_V3:
> +        max_vcpus = 4092;

The previous case was using 4096. Also, can you move the comment to keep the 
rationale for the number?

> +        break;
> +#endif
> +
> +    default:
> +        return 0;
> +    }
> +
> +    return min_t(unsigned int, MAX_VIRT_CPUS, max_vcpus);

How about moving this check in the common code?

Cheers,

-- 
Julien Grall

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