Re: [PATCH v4 1/3] domctl: introduce a new domain create flag, XEN_DOMCTL_CDF_disable_fifo, ...

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/11/2020 19:17, Paul Durrant wrote:
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index 666aeb71bf1b..70701c59d053 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -70,9 +70,11 @@ struct xen_domctl_createdomain {
>  #define XEN_DOMCTL_CDF_iommu          (1U<<_XEN_DOMCTL_CDF_iommu)
>  #define _XEN_DOMCTL_CDF_nested_virt   6
>  #define XEN_DOMCTL_CDF_nested_virt    (1U << _XEN_DOMCTL_CDF_nested_virt)
> +#define _XEN_DOMCTL_CDF_disable_fifo  7
> +#define XEN_DOMCTL_CDF_disable_fifo   (1U << _XEN_DOMCTL_CDF_disable_fifo)

The sense is backwards.  It should be a "permit the use of FIFO"
control.  If the code had been written this way to begin with, the bug
you found wouldn't have existed.

Given that there is not currently a way to disable FIFO, you can
probably do without an enumeration of whether the hypervisor supports it
or not.

~Andrew