diff --git a/Makefile b/Makefile
index 7b8eac42..bdf94c9e 100644
--- a/Makefile
+++ b/Makefile
@@ -204,8 +204,13 @@ endif
 ifeq ($(plat_mem),non_unified)
 	build_macros+=-DMEM_NON_UNIFIED
 endif
-ifeq ($(phys_irqs_only),y)
-	build_macros+=-DPHYS_IRQS_ONLY
+
+ifeq ($(mmio_slave_side_prot),y)
+	build_macros+=-DMMIO_SLAVE_SIDE_PROT
+
+	ifneq ($(arch_mem_prot),mpu)
+		$(error mmio_slave_side_prot=y requires arch_mem_prot=mpu)
+	endif
 endif
 
 ifeq ($(CC_IS_GCC),y)
diff --git a/src/core/inc/platform.h b/src/core/inc/platform.h
index ac91015f..11d8adee 100644
--- a/src/core/inc/platform.h
+++ b/src/core/inc/platform.h
@@ -21,6 +21,8 @@ struct platform {
     size_t region_num;
     struct mem_region* regions;
 
+    size_t mmio_region_num;
+    struct mem_region* mmio_regions;
     struct {
         paddr_t base;
     } console;
diff --git a/src/core/inc/vm.h b/src/core/inc/vm.h
index 2d0686ed..1eabed97 100644
--- a/src/core/inc/vm.h
+++ b/src/core/inc/vm.h
@@ -183,5 +183,6 @@ unsigned long vcpu_readpc(struct vcpu* vcpu);
 void vcpu_writepc(struct vcpu* vcpu, unsigned long pc);
 void vcpu_arch_reset(struct vcpu* vcpu, vaddr_t entry);
 bool vcpu_arch_is_on(struct vcpu* vcpu);
+void vm_arch_allow_mmio_access(struct vm* vm, struct vm_dev_region* dev);
 
 #endif /* __VM_H__ */
diff --git a/src/core/mpu/mem.c b/src/core/mpu/mem.c
index 73447e39..c63af79c 100644
--- a/src/core/mpu/mem.c
+++ b/src/core/mpu/mem.c
@@ -214,6 +214,15 @@ size_t mem_cpu_boot_alloc_size()
     return size;
 }
 
+static void mem_mmio_init_regions(struct addr_space* as)
+{
+    for (unsigned long i = 0; i < platform.mmio_region_num; i++) {
+        mem_alloc_map_dev(as, as->type == AS_VM ? SEC_VM_ANY : SEC_HYP_ANY,
+            platform.mmio_regions[i].base, platform.mmio_regions[i].base,
+            NUM_PAGES(platform.mmio_regions[i].size));
+    }
+}
+
 void as_init(struct addr_space* as, enum AS_TYPE type, asid_t id, colormap_t colors)
 {
     UNUSED_ARG(colors);
@@ -229,6 +238,12 @@ void as_init(struct addr_space* as, enum AS_TYPE type, asid_t id, colormap_t col
     for (size_t i = 0; i < VMPU_NUM_ENTRIES; i++) {
         mem_vmpu_free_entry(as, i);
     }
+
+    /* For architectures with slave-side mmio protection, we map all the
+    mmio regions to be accessible to all address spaces */
+    if (DEFINED(MMIO_SLAVE_SIDE_PROT)) {
+        mem_mmio_init_regions(as);
+    }
 }
 
 static void mem_free_ppages(struct ppages* ppages)
diff --git a/src/core/vm.c b/src/core/vm.c
index fed31e1c..d94fee7e 100644
--- a/src/core/vm.c
+++ b/src/core/vm.c
@@ -20,8 +20,6 @@ static void vm_master_init(struct vm* vm, const struct vm_config* vm_config, vmi
     vm->lock = SPINLOCK_INITVAL;
 
     cpu_sync_init(&vm->sync, vm->cpu_num);
-
-    vm_mem_prot_init(vm, vm_config);
 }
 
 static void vm_cpu_init(struct vm* vm)
@@ -210,9 +208,10 @@ static void vm_init_dev(struct vm* vm, const struct vm_config* vm_config)
     for (size_t i = 0; i < vm_config->platform.dev_num; i++) {
         struct vm_dev_region* dev = &vm_config->platform.devs[i];
 
-        size_t n = ALIGN(dev->size, PAGE_SIZE) / PAGE_SIZE;
-
-        if (dev->va != INVALID_VA) {
+        if (DEFINED(MMIO_SLAVE_SIDE_PROT)) {
+            vm_arch_allow_mmio_access(vm, dev);
+        } else if (dev->va != INVALID_VA) {
+            size_t n = ALIGN(dev->size, PAGE_SIZE) / PAGE_SIZE;
             mem_alloc_map_dev(&vm->as, SEC_VM_ANY, (vaddr_t)dev->va, dev->pa, n);
         }
 
@@ -319,6 +318,12 @@ struct vm* vm_init(struct vm_allocation* vm_alloc, const struct vm_config* vm_co
 
     cpu_sync_barrier(&vm->sync);
 
+    if (master) {
+        vm_mem_prot_init(vm, vm_config);
+    }
+
+    cpu_sync_barrier(&vm->sync);
+
     /**
      * Perform architecture dependent initializations. This includes, for example, setting the page
      * table pointer and other virtualization extensions specifics.
@@ -422,3 +427,11 @@ void vcpu_run(struct vcpu* vcpu)
         cpu_powerdown();
     }
 }
+
+__attribute__((weak)) void vm_arch_allow_mmio_access(struct vm* vm, struct vm_dev_region* dev)
+{
+    UNUSED_ARG(dev);
+    UNUSED_ARG(vm);
+    ERROR("vm_arch_allow_mmio_access must be implemented by the arch!")
+    return;
+}