Re: [Xen-devel] [PATCH 07/17] ARM: VGIC: Adjust domain_max_vcpus() to be VGIC specific

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 09/03/18 15:11, Andre Przywara wrote:
> domain_max_vcpus(), which is used by generic Xen code, returns the
> maximum number of VCPUs for a domain, which on ARM is mostly limited by
> the VGIC model emulated (a (v)GICv2 can only handle 8 CPUs).
> Our current implementation lives in arch/arm/domain.c, but reaches into
> VGIC internal data structures.
> Move the actual functionality into vgic.c, and provide a shim in
> domain.h, to keep this VGIC internal.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
Reviewed-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
> Changelog:
> - rename helper function and wrap in domain.h
>
>   xen/arch/arm/domain.c        | 14 --------------
>   xen/arch/arm/vgic.c          | 14 ++++++++++++++
>   xen/include/asm-arm/domain.h |  6 +++++-
>   xen/include/asm-arm/vgic.h   |  2 ++
>   4 files changed, 21 insertions(+), 15 deletions(-)
>
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 8de4c0a343..6b902fa30f 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -967,20 +967,6 @@ void vcpu_block_unless_event_pending(struct vcpu *v)
>           vcpu_unblock(current);
>   }
>   
> -unsigned int domain_max_vcpus(const struct domain *d)
> -{
> -    /*
> -     * Since evtchn_init would call domain_max_vcpus for poll_mask
> -     * allocation when the vgic_ops haven't been initialised yet,
> -     * we return MAX_VIRT_CPUS if d->arch.vgic.handler is null.
> -     */
> -    if ( !d->arch.vgic.handler )
> -        return MAX_VIRT_CPUS;
> -    else
> -        return min_t(unsigned int, MAX_VIRT_CPUS,
> -                     d->arch.vgic.handler->max_vcpus);
> -}
> -
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index 34269bcf27..fa00c21a69 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -665,6 +665,20 @@ 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)
> +{
> +    /*
> +     * Since evtchn_init would call domain_max_vcpus for poll_mask
> +     * allocation when the vgic_ops haven't been initialised yet,
> +     * we return MAX_VIRT_CPUS if d->arch.vgic.handler is null.
> +     */
> +    if ( !d->arch.vgic.handler )
> +        return MAX_VIRT_CPUS;
> +    else
> +        return min_t(unsigned int, MAX_VIRT_CPUS,
> +                     d->arch.vgic.handler->max_vcpus);
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index c6aa5cf389..e730e07fcf 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -289,7 +289,11 @@ void vcpu_show_execution_state(struct vcpu *);
>   void vcpu_show_registers(const struct vcpu *);
>   void vcpu_switch_to_aarch64_mode(struct vcpu *);
>   
> -unsigned int domain_max_vcpus(const struct domain *);
> +/* On ARM, the number of VCPUs is limited by the type of GIC emulated. */
> +static inline unsigned int domain_max_vcpus(const struct domain *d)
> +{
> +    return vgic_max_vcpus(d);
> +}
>   
>   /*
>    * Due to the restriction of GICv3, the number of vCPUs in AFF0 is
> diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
> index d03298e12c..afb4776ad4 100644
> --- a/xen/include/asm-arm/vgic.h
> +++ b/xen/include/asm-arm/vgic.h
> @@ -254,6 +254,8 @@ static inline int vgic_allocate_spi(struct domain *d)
>   
>   extern void vgic_free_virq(struct domain *d, unsigned int virq);
>   
> +unsigned int vgic_max_vcpus(const struct domain *d);
> +
>   void vgic_v2_setup_hw(paddr_t dbase, paddr_t cbase, paddr_t csize,
>                         paddr_t vbase, uint32_t aliased_offset);
>   
--
Julien Grall

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