xen: remove global bit from __default_kernel_pte_mask for pv guests

When removing the global bit from __supported_pte_mask do the same for
__default_kernel_pte_mask in order to avoid the WARN_ONCE() in
check_pgprot() when setting a kernel pte before having called
init_mem_mapping().

Cc: <[email protected]> # 4.17
Reported-by: Michael Young <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>

Author: jgross1

arch/x86/xen/enlighten_pv.c

@@ -1229,6 +1229,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 
 	/* Prevent unwanted bits from being set in PTEs. */
 	__supported_pte_mask &= ~_PAGE_GLOBAL;
+	__default_kernel_pte_mask &= ~_PAGE_GLOBAL;
 
 	/*
 	 * Prevent page tables from being allocated in highmem, even