Re: [RFC PATCH 2/2] xen/arm: introduce XENFEAT_grant_map_11

["Jan Beulich" <JBeulich@suse.com>]

>>> On 08.07.14 at 17:53, <stefano.stabellini@eu.citrix.com> wrote:
> --- a/xen/common/kernel.c
> +++ b/xen/common/kernel.c
> @@ -325,6 +325,10 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
>                  break;
>              }
>  #endif
> +#ifdef CONFIG_ARM
> +            if ( is_domain_direct_mapped(d) )

The #ifdef and if() seem kind of redundant - can't x86 simply get a
stub always returning false?

> --- a/xen/include/asm-arm/grant_table.h
> +++ b/xen/include/asm-arm/grant_table.h
> @@ -33,8 +33,7 @@ static inline int replace_grant_supported(void)
>      ( ((i >= nr_grant_frames(d->grant_table)) &&                         \
>       (i < max_nr_grant_frames)) ? 0 : (d->arch.grant_table_gpfn[i]))
>  
> -#define gnttab_need_iommu_mapping(d)                    \
> -    (is_domain_direct_mapped(d) && need_iommu(d))
> +#define gnttab_need_iommu_mapping(d)            (is_domain_direct_mapped(d))

How is this change related to the subject of the patch?

> --- a/xen/include/public/features.h
> +++ b/xen/include/public/features.h
> @@ -94,6 +94,9 @@
>  /* operation as Dom0 is supported */
>  #define XENFEAT_dom0                      11
>  
> +/* Xen also maps grant references at pfn = mfn */
> +#define XENFEAT_grant_map_11              12

As already said by others, this needs a better name.

Jan