Re: [PATCH V4 8/8] xen/arm: make domain_max_vcpus return value according to vGIC version

[Julien Grall <julien.grall@citrix.com>]

Hi Chen,

On 28/05/15 11:15, Chen Baozi wrote:
> From: Chen Baozi <baozich@gmail.com>
> 
> When a guest uses vGICv2, the maximum number of vCPU it can support
> should not be as many as MAX_VIRT_CPUS, which is 128 at the moment.
> So the domain_max_vcpus should return the value according to the vGIC
> version the domain uses.
> 
> We didn't keep it as the old static inline form because it will break
> compilation when access the member of struct domain:
> 
> In file included from xen/include/xen/domain.h:6:0,
>                  from xen/include/xen/sched.h:10,
>                  from arm64/asm-offsets.c:10:
> xen/include/asm/domain.h: In function ‘domain_max_vcpus’:
> xen/include/asm/domain.h:266:10: error: dereferencing pointer to incomplete type
>      if (d->arch.vgic.version == GIC_V2)
>           ^
> 
> Signed-off-by: Chen Baozi <baozich@gmail.com>
> ---
>  xen/arch/arm/domain.c        | 6 ++++++
>  xen/include/asm-arm/domain.h | 5 +----
>  xen/include/asm-arm/gic.h    | 3 +++
>  3 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 0cf147c..78b77b1 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -890,6 +890,12 @@ void vcpu_block_unless_event_pending(struct vcpu *v)
>          vcpu_unblock(current);
>  }
>  
> +unsigned int domain_max_vcpus(const struct domain *d)
> +{
> +    return ((d->arch.vgic.version == GIC_V2) ?
> +            GICV2_MAX_CPUS : GICV3_MAX_CPUS);

We try to get the common code vgic agnostic. With this solution every
time a new vGIC driver is added you have to modify domain_max_vcpus.

As suggested on a previous version, I would prefer to extend the
vgic_ops to store the maximum number of VCPU handled by the vGIC.

Regards,

-- 
Julien Grall

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