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SubjectRe: [PATCH 1/6] xen/pvh: Support ParaVirtualized Hardware extensions.
> +/*
> + * Unmaps the page appearing at a particular GPFN from the specified guest's
> + * pseudophysical address space.
> + * arg == addr of xen_remove_from_physmap_t.
> + */
> +#define XENMEM_remove_from_physmap 15
> +struct xen_remove_from_physmap {
> + /* Which domain to change the mapping for. */
> + domid_t domid;
> +
> + /* GPFN of the current mapping of the page. */
> + xen_pfn_t gpfn;
> +};

I just realized that this a bit of unfortunate. We end up
with on 64-bit with this layout:

{
0->1 [domid]
2->7 [nothing]
8->16 [gpfn]

}

which if one were to do a 32-bit build you would get:
{
0->1 [domid]
2->3 [nothing]
4->7 [gpfn]
}
which means another compat layer in Xen.

So I think it makes sense to modify this to be 32 and 64-bit
clean, something like this:

{
domid_t domid;
u8 pad[6];
xen_pfn_t gpfn;
/* xen_pfn_t under 32-bit x86 is 4 bytes, so extend it */
#ifdef CONFIG_X86_32
__u8 pad1[4];
#endif
}

that way the structure is exactly the same size and the offsets
align.

Mukesh, you OK with that?


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