ARM: kvm: define PAGE_S2_DEVICE as read-only by default

Now that we support read-only memslots, we need to make sure that
pass-through device mappings are not mapped writable if the guest
has requested them to be read-only. The existing implementation
already honours this by calling kvm_set_s2pte_writable() on the new
pte in case of writable mappings, so all we need to do is define
the default pgprot_t value used for devices to be PTE_S2_RDONLY.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 01baef0..92b2fbe 100644 (file)
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -100,7 +100,7 @@ extern pgprot_t             pgprot_s2_device;
 #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_S2_RDWR)
+#define PAGE_S2_DEVICE         _MOD_PROT(pgprot_s2_device, 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)