x86/xen: fix memblock_reserve() usage on PVH

commit 4c006734 upstream.

The current usage of memblock_reserve() in init_pvh_bootparams() is done before
the .bss is zeroed, and that used to be fine when
memblock_reserved_init_regions implicitly ended up in the .meminit.data
section.  However after commit 73db3abd memblock_reserved_init_regions
ends up in the .bss section, thus breaking it's usage before the .bss is
cleared.

Move and rename the call to xen_reserve_extra_memory() so it's done in the
x86_init.oem.arch_setup hook, which gets executed after the .bss has been
zeroed, but before calling e820__memory_setup().

Fixes: 73db3abd ("init/modpost: conditionally check section mismatch to __meminit*")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Message-ID: <20240725073116.14626-3-roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
[ Context fixup for hypercall_page removal ]
Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>