[PATCH RESEND] arm64: KVM: Add Kconfig option for max VCPUs per-Guest

[christoffer.dall@linaro.org (Christoffer Dall)]

On Thu, Dec 12, 2013 at 09:42:22PM +0530, Anup Patel wrote:
> Current max VCPUs per-Guest is set to 4 which is preventing
> us from creating a Guest (or VM) with 8 VCPUs on Host (e.g.
> X-Gene Storm SOC) with 8 Host CPUs.
> 
> The correct value of max VCPUs per-Guest should be same as
> the max CPUs supported by GICv2 which is 8 but, increasing
> value of max VCPUs per-Guest can make things slower hence
> we add Kconfig option to let KVM users select appropriate
> max VCPUs per-Guest.
> 

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>

> Signed-off-by: Anup Patel <anup.patel@linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> ---
>  arch/arm64/include/asm/kvm_host.h |    7 ++++++-
>  arch/arm64/kvm/Kconfig            |   11 +++++++++++
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 5d85a02..0a1d697 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -26,7 +26,12 @@
>  #include <asm/kvm_asm.h>
>  #include <asm/kvm_mmio.h>
>  
> -#define KVM_MAX_VCPUS 4
> +#if defined(CONFIG_KVM_ARM_MAX_VCPUS)
> +#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
> +#else
> +#define KVM_MAX_VCPUS 0
> +#endif
> +
>  #define KVM_USER_MEM_SLOTS 32
>  #define KVM_PRIVATE_MEM_SLOTS 4
>  #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 4480ab3..8ba85e9 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -36,6 +36,17 @@ config KVM_ARM_HOST
>  	---help---
>  	  Provides host support for ARM processors.
>  
> +config KVM_ARM_MAX_VCPUS
> +	int "Number maximum supported virtual CPUs per VM"
> +	depends on KVM_ARM_HOST
> +	default 4
> +	help
> +	  Static number of max supported virtual CPUs per VM.
> +
> +	  If you choose a high number, the vcpu structures will be quite
> +	  large, so only choose a reasonable number that you expect to
> +	  actually use.
> +
>  config KVM_ARM_VGIC
>  	bool
>  	depends on KVM_ARM_HOST && OF
> -- 
> 1.7.9.5
> 

-- 
Christoffer