diff --git a/hw/microblaze/petalogix_s3adsp1800_mmu.c b/hw/microblaze/petalogix_s3adsp1800_mmu.c
index 5cf7b84c79..b9f0b0d06e 100644
--- a/hw/microblaze/petalogix_s3adsp1800_mmu.c
+++ b/hw/microblaze/petalogix_s3adsp1800_mmu.c
@@ -35,6 +35,7 @@
 #include "sysemu/sysemu.h"
 #include "hw/devices.h"
 #include "hw/boards.h"
+#include "hw/misc/unimp.h"
 #include "exec/address-spaces.h"
 #include "hw/char/xilinx_uartlite.h"
 
@@ -47,6 +48,7 @@
 
 #define MEMORY_BASEADDR 0x90000000
 #define FLASH_BASEADDR 0xa0000000
+#define GPIO_BASEADDR 0x81400000
 #define INTC_BASEADDR 0x81800000
 #define TIMER_BASEADDR 0x83c00000
 #define UARTLITE_BASEADDR 0x84000000
@@ -122,6 +124,8 @@ petalogix_s3adsp1800_init(MachineState *machine)
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, ETHLITE_BASEADDR);
     sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, irq[ETHLITE_IRQ]);
 
+    create_unimplemented_device("gpio", GPIO_BASEADDR, 0x10000);
+
     microblaze_load_kernel(cpu, ddr_base, ram_size,
                            machine->initrd_filename,
                            BINARY_DEVICE_TREE_FILE,
diff --git a/target/microblaze/cpu.c b/target/microblaze/cpu.c
index 9b546a2c18..5596cd5485 100644
--- a/target/microblaze/cpu.c
+++ b/target/microblaze/cpu.c
@@ -202,7 +202,11 @@ static void mb_cpu_realizefn(DeviceState *dev, Error **errp)
                         (cpu->cfg.use_barrel ? PVR2_USE_BARREL_MASK : 0) |
                         (cpu->cfg.use_div ? PVR2_USE_DIV_MASK : 0) |
                         (cpu->cfg.use_msr_instr ? PVR2_USE_MSR_INSTR : 0) |
-                        (cpu->cfg.use_pcmp_instr ? PVR2_USE_PCMP_INSTR : 0);
+                        (cpu->cfg.use_pcmp_instr ? PVR2_USE_PCMP_INSTR : 0) |
+                        (cpu->cfg.dopb_bus_exception ?
+                                                 PVR2_DOPB_BUS_EXC_MASK : 0) |
+                        (cpu->cfg.iopb_bus_exception ?
+                                                 PVR2_IOPB_BUS_EXC_MASK : 0);
 
     env->pvr.regs[5] |= cpu->cfg.dcache_writeback ?
                                         PVR5_DCACHE_WRITEBACK_MASK : 0;
@@ -265,6 +269,12 @@ static Property mb_properties[] = {
     DEFINE_PROP_BOOL("dcache-writeback", MicroBlazeCPU, cfg.dcache_writeback,
                      false),
     DEFINE_PROP_BOOL("endianness", MicroBlazeCPU, cfg.endi, false),
+    /* Enables bus exceptions on failed data accesses (load/stores).  */
+    DEFINE_PROP_BOOL("dopb-bus-exception", MicroBlazeCPU,
+                     cfg.dopb_bus_exception, false),
+    /* Enables bus exceptions on failed instruction fetches.  */
+    DEFINE_PROP_BOOL("iopb-bus-exception", MicroBlazeCPU,
+                     cfg.iopb_bus_exception, false),
     DEFINE_PROP_STRING("version", MicroBlazeCPU, cfg.version),
     DEFINE_PROP_UINT8("pvr", MicroBlazeCPU, cfg.pvr, C_PVR_FULL),
     DEFINE_PROP_END_OF_LIST(),
@@ -297,7 +307,7 @@ static void mb_cpu_class_init(ObjectClass *oc, void *data)
 #ifdef CONFIG_USER_ONLY
     cc->handle_mmu_fault = mb_cpu_handle_mmu_fault;
 #else
-    cc->do_unassigned_access = mb_cpu_unassigned_access;
+    cc->do_transaction_failed = mb_cpu_transaction_failed;
     cc->get_phys_page_debug = mb_cpu_get_phys_page_debug;
 #endif
     dc->vmsd = &vmstate_mb_cpu;
diff --git a/target/microblaze/cpu.h b/target/microblaze/cpu.h
index 3c4e0ba80a..792bbc97c7 100644
--- a/target/microblaze/cpu.h
+++ b/target/microblaze/cpu.h
@@ -308,6 +308,8 @@ struct MicroBlazeCPU {
         bool use_mmu;
         bool dcache_writeback;
         bool endi;
+        bool dopb_bus_exception;
+        bool iopb_bus_exception;
         char *version;
         uint8_t pvr;
     } cfg;
@@ -388,9 +390,10 @@ static inline void cpu_get_tb_cpu_state(CPUMBState *env, target_ulong *pc,
 }
 
 #if !defined(CONFIG_USER_ONLY)
-void mb_cpu_unassigned_access(CPUState *cpu, hwaddr addr,
-                              bool is_write, bool is_exec, int is_asi,
-                              unsigned size);
+void mb_cpu_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr,
+                               unsigned size, MMUAccessType access_type,
+                               int mmu_idx, MemTxAttrs attrs,
+                               MemTxResult response, uintptr_t retaddr);
 #endif
 
 #endif
diff --git a/target/microblaze/op_helper.c b/target/microblaze/op_helper.c
index 7cdbbcccae..e23dcfdc20 100644
--- a/target/microblaze/op_helper.c
+++ b/target/microblaze/op_helper.c
@@ -486,26 +486,28 @@ void helper_mmu_write(CPUMBState *env, uint32_t ext, uint32_t rn, uint32_t v)
     mmu_write(env, ext, rn, v);
 }
 
-void mb_cpu_unassigned_access(CPUState *cs, hwaddr addr,
-                              bool is_write, bool is_exec, int is_asi,
-                              unsigned size)
+void mb_cpu_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr,
+                               unsigned size, MMUAccessType access_type,
+                               int mmu_idx, MemTxAttrs attrs,
+                               MemTxResult response, uintptr_t retaddr)
 {
     MicroBlazeCPU *cpu;
     CPUMBState *env;
-
-    qemu_log_mask(CPU_LOG_INT, "Unassigned " TARGET_FMT_plx " wr=%d exe=%d\n",
-             addr, is_write ? 1 : 0, is_exec ? 1 : 0);
-    if (cs == NULL) {
-        return;
-    }
+    qemu_log_mask(CPU_LOG_INT, "Transaction failed: vaddr 0x%" VADDR_PRIx
+                  " physaddr 0x" TARGET_FMT_plx " size %d access type %s\n",
+                  addr, physaddr, size,
+                  access_type == MMU_INST_FETCH ? "INST_FETCH" :
+                  (access_type == MMU_DATA_LOAD ? "DATA_LOAD" : "DATA_STORE"));
     cpu = MICROBLAZE_CPU(cs);
     env = &cpu->env;
+
+    cpu_restore_state(cs, retaddr, true);
     if (!(env->sregs[SR_MSR] & MSR_EE)) {
         return;
     }
 
     env->sregs[SR_EAR] = addr;
-    if (is_exec) {
+    if (access_type == MMU_INST_FETCH) {
         if ((env->pvr.regs[2] & PVR2_IOPB_BUS_EXC_MASK)) {
             env->sregs[SR_ESR] = ESR_EC_INSN_BUS;
             helper_raise_exception(env, EXCP_HW_EXCP);