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SubjectRe: [PATCH 1/2] xen/granttable: Support sub-page grants

> +void gnttab_grant_foreign_access_ref_subpage_v2(grant_ref_t ref, domid_t domid,
> + unsigned long frame, int flags,
> + unsigned page_off,
> + unsigned length)
> +{
> + BUG_ON(flags& (GTF_accept_transfer | GTF_reading |
> + GTF_writing | GTF_transitive));
This is slightly changed from the initial code, welcome your suggestions.

Initial condition is:
BUG_ON(flags & (GTF_accept_transfer | GTF_reading | GTF_writing |
GTF_sub_page | GTF_permit_access));
GTF_sub_page | GTF_permit_access will be set later in this function, so
it is necessary to verify this flag here.
GTF_transitive and GTF_sub_page can not be enabled at same time, so
GTF_transitive is checked here to avoid those two flags are both enabled.
Same code was changed in corresponding transitive function.

Thanks
Annie
> + BUG_ON(grant_table_version == 1);
> + gnttab_shared.v2[ref].sub_page.frame = frame;
> + gnttab_shared.v2[ref].sub_page.page_off = page_off;
> + gnttab_shared.v2[ref].sub_page.length = length;
> + gnttab_shared.v2[ref].hdr.domid = domid;
> + wmb();
> + gnttab_shared.v2[ref].hdr.flags =
> + GTF_permit_access | GTF_sub_page | flags;
> +}
>


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