Re: [Xen-devel] [PATCH] gnttab/ARM: properly implement gnttab_create_status_page()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 15 Aug 2018, Jan Beulich wrote:
> Prevent the "BUG_ON(page_get_owner(pg) != d)" in
> gnttab_unpopulate_status_frames() from triggering.
> 
> Reported-by: 王磊 <lei19.wang@xxxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> ---
> It looks to me as if this was the only piece missing to make v2 grant
> tables work on ARM, but this was build tested only anyway.

For the public records, it cannot be tested until the Linux (or other
OSes functionalities) get implemented. Specifically,
arch_gnttab_map_shared and arch_gnttab_map_status in Linux.

But this patch is a clear improvement on the Xen side:

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> --- a/xen/include/asm-arm/grant_table.h
> +++ b/xen/include/asm-arm/grant_table.h
> @@ -21,7 +21,6 @@ int create_grant_host_mapping(unsigned l
>  int replace_grant_host_mapping(unsigned long gpaddr, mfn_t mfn,
>                                 unsigned long new_gpaddr, unsigned int flags);
>  void gnttab_mark_dirty(struct domain *d, mfn_t mfn);
> -#define gnttab_create_status_page(d, t, i) do {} while (0)
>  #define gnttab_release_host_mappings(domain) 1
>  static inline int replace_grant_supported(void)
>  {
> @@ -84,6 +83,12 @@ static inline unsigned int gnttab_dom0_m
>              virt_to_page((char *)(t)->shared_raw[i]), d, SHARE_rw);      \
>      } while ( 0 )
>  
> +#define gnttab_create_status_page(d, t, i)                               \
> +    do {                                                                 \
> +        share_xen_page_with_guest(                                       \
> +            virt_to_page((char *)(t)->status[i]), d, SHARE_rw);          \
> +    } while ( 0 )
> +
>  #define gnttab_shared_gmfn(d, t, i)                                      \
>      gfn_x(((i) >= nr_grant_frames(t)) ? INVALID_GFN : 
> (t)->arch.shared_gfn[i])
>  
>

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