ARM: Add page table and page defines needed by KVM

KVM uses the stage-2 page tables and the Hyp page table format,
so we define the fields and page protection flags needed by KVM.

The nomenclature is this:
 - page_hyp:        PL2 code/data mappings
 - page_hyp_device: PL2 device mappings (vgic access)
 - page_s2:         Stage-2 code/data page mappings
 - page_s2_device:  Stage-2 device mappings (vgic access)

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Christoffer Dall <c.dall@virtualopensystems.com>
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9c82f988..f30ac3b 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -70,6 +70,9 @@
 
 extern pgprot_t		pgprot_user;
 extern pgprot_t		pgprot_kernel;
+extern pgprot_t		pgprot_hyp_device;
+extern pgprot_t		pgprot_s2;
+extern pgprot_t		pgprot_s2_device;
 
 #define _MOD_PROT(p, b)	__pgprot(pgprot_val(p) | (b))
 
@@ -82,6 +85,10 @@
 #define PAGE_READONLY_EXEC	_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY)
 #define PAGE_KERNEL		_MOD_PROT(pgprot_kernel, L_PTE_XN)
 #define PAGE_KERNEL_EXEC	pgprot_kernel
+#define PAGE_HYP		_MOD_PROT(pgprot_kernel, L_PTE_HYP)
+#define PAGE_HYP_DEVICE		_MOD_PROT(pgprot_hyp_device, L_PTE_HYP)
+#define PAGE_S2			_MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY)
+#define PAGE_S2_DEVICE		_MOD_PROT(pgprot_s2_device, L_PTE_USER | L_PTE_S2_RDONLY)
 
 #define __PAGE_NONE		__pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE)
 #define __PAGE_SHARED		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN)