Subject: Re: [PATCH kernel 1/9] KVM: PPC: Reserve KVM_CAP_SPAPR_TCE_VFIO capability number

From: David Gibson <[email-masked]>
Date: Mon, 12 Dec 2016 15:08:16 +1100

On Thu, Dec 08, 2016 at 07:19:48PM +1100, Alexey Kardashevskiy wrote:
> This adds a capability number for in-kernel support for VFIO on
> SPAPR platform.
> 
> The capability will tell the user space whether in-kernel handlers of
> H_PUT_TCE can handle VFIO-targeted requests or not. If not, the user space
> must not attempt allocating a TCE table in the host kernel via
> the KVM_CREATE_SPAPR_TCE KVM ioctl because in that case TCE requests
> will not be passed to the user space which is desired action in
> the situation like that.
> 
> Signed-off-by: Alexey Kardashevskiy <[email-masked]>
> Reviewed-by: David Gibson <[email-masked]>

Fine as far as it goes, although I wonder if you actually need a new
CAP - couldn't you just add a new cap value to KVM_CAP_SPAPR_TCE?

> ---
>  include/uapi/linux/kvm.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 300ef255d1e0..810f74317987 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -870,6 +870,7 @@ struct kvm_ppc_smmu_info {
>  #define KVM_CAP_S390_USER_INSTR0 130
>  #define KVM_CAP_MSI_DEVID 131
>  #define KVM_CAP_PPC_HTM 132
> +#define KVM_CAP_SPAPR_TCE_VFIO 133
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  

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