arm/arm64: KVM: Map the HYP text as read-only

There should be no reason for mapping the HYP text read/write.

As such, let's have a new set of flags (PAGE_HYP_EXEC) that allows
execution, but makes the page as read-only, and update the two call
sites that deal with mapping code.

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

arch/arm/kvm/mmu.c

@@ -1733,7 +1733,7 @@ int kvm_mmu_init(void)
 	err = 	__create_hyp_mappings(boot_hyp_pgd,
 				      hyp_idmap_start, hyp_idmap_end,
 				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP);
+				      PAGE_HYP_EXEC);
 
 	if (err) {
 		kvm_err("Failed to idmap %lx-%lx\n",
@@ -1756,7 +1756,7 @@ int kvm_mmu_init(void)
 	err = 	__create_hyp_mappings(boot_hyp_pgd,
 				      TRAMPOLINE_VA, TRAMPOLINE_VA + PAGE_SIZE,
 				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP);
+				      PAGE_HYP_EXEC);
 	if (err) {
 		kvm_err("Failed to map trampoline @%lx into boot HYP pgd\n",
 			TRAMPOLINE_VA);
@@ -1767,7 +1767,7 @@ int kvm_mmu_init(void)
 	err = 	__create_hyp_mappings(hyp_pgd,
 				      TRAMPOLINE_VA, TRAMPOLINE_VA + PAGE_SIZE,
 				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP);
+				      PAGE_HYP_EXEC);
 	if (err) {
 		kvm_err("Failed to map trampoline @%lx into runtime HYP pgd\n",
 			TRAMPOLINE_VA);