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

[Andrew Cooper <andrew.cooper3@citrix.com>]

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>

Looks much better!

It is a shame about the compilation issue - I had a similar issue on the
x86 side.  At some point, I need to untangle the rats nest which is our
currently header file layout, so that we don't have to rely on tricks
like this to keep it compiling.

~Andrew

> ---
>  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);
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 603a20b..c4cb15d 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -261,10 +261,7 @@ struct arch_vcpu
>  void vcpu_show_execution_state(struct vcpu *);
>  void vcpu_show_registers(const struct vcpu *);
>  
> -static inline unsigned int domain_max_vcpus(const struct domain *d)
> -{
> -    return MAX_VIRT_CPUS;
> -}
> +unsigned int domain_max_vcpus(const struct domain *);
>  
>  /*
>   * Due to the restriction of GICv3, the number of vCPUs in AFF0 is
> diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
> index 463fffb..a7bc0d1 100644
> --- a/xen/include/asm-arm/gic.h
> +++ b/xen/include/asm-arm/gic.h
> @@ -18,6 +18,9 @@
>  #ifndef __ASM_ARM_GIC_H__
>  #define __ASM_ARM_GIC_H__
>  
> +#define GICV2_MAX_CPUS  8
> +#define GICV3_MAX_CPUS  128
> +
>  #define NR_GIC_LOCAL_IRQS  NR_LOCAL_IRQS
>  #define NR_GIC_SGI         16
>  #define MAX_RDIST_COUNT    4


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