diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 4bdceb45a14f..4ef0b73559ca 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1681,6 +1681,22 @@ static const VMStateDescription vmstate_spapr_patb_entry = {
     },
 };
 
+static bool spapr_irq_map_needed(void *opaque)
+{
+    return true;
+}
+
+static const VMStateDescription vmstate_spapr_irq_map = {
+    .name = "spapr_irq_map",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .needed = spapr_irq_map_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_BITMAP(irq_map, sPAPRMachineState, 0, nr_irqs),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static const VMStateDescription vmstate_spapr = {
     .name = "spapr",
     .version_id = 3,
@@ -1700,6 +1716,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_ov5_cas,
         &vmstate_spapr_patb_entry,
         &vmstate_spapr_pending_events,
+        &vmstate_spapr_irq_map,
         NULL
     }
 };
@@ -2337,8 +2354,12 @@ static void ppc_spapr_init(MachineState *machine)
     /* Setup a load limit for the ramdisk leaving room for SLOF and FDT */
     load_limit = MIN(spapr->rma_size, RTAS_MAX_ADDR) - FW_OVERHEAD;
 
+    /* Initialize the IRQ allocator */
+    spapr->nr_irqs  = XICS_IRQS_SPAPR;
+    spapr->irq_map  = bitmap_new(spapr->nr_irqs);
+
     /* Set up Interrupt Controller before we create the VCPUs */
-    xics_system_init(machine, XICS_IRQS_SPAPR, &error_fatal);
+    xics_system_init(machine, spapr->nr_irqs, &error_fatal);
 
     /* Set up containers for ibm,client-architecture-support negotiated options
      */
@@ -3560,7 +3581,7 @@ static int ics_find_free_block(ICSState *ics, int num, int alignnum)
     return -1;
 }
 
-static bool spapr_irq_test(XICSFabric *xi, int irq)
+static bool spapr_irq_test_2_11(XICSFabric *xi, int irq)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
     ICSState *ics = spapr->ics;
@@ -3569,7 +3590,7 @@ static bool spapr_irq_test(XICSFabric *xi, int irq)
     return !ICS_IRQ_FREE(ics, srcno);
 }
 
-static int spapr_irq_alloc_block(XICSFabric *xi, int count, int align)
+static int spapr_irq_alloc_block_2_11(XICSFabric *xi, int count, int align)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
     ICSState *ics = spapr->ics;
@@ -3583,7 +3604,7 @@ static int spapr_irq_alloc_block(XICSFabric *xi, int count, int align)
     return srcno + ics->offset;
 }
 
-static void spapr_irq_free_block(XICSFabric *xi, int irq, int num)
+static void spapr_irq_free_block_2_11(XICSFabric *xi, int irq, int num)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
     ICSState *ics = spapr->ics;
@@ -3601,6 +3622,46 @@ static void spapr_irq_free_block(XICSFabric *xi, int irq, int num)
     }
 }
 
+static bool spapr_irq_test(XICSFabric *xi, int irq)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
+    int srcno = irq - spapr->ics->offset;
+
+    return test_bit(srcno, spapr->irq_map);
+}
+
+static int spapr_irq_alloc_block(XICSFabric *xi, int count, int align)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
+    int start = 0;
+    int srcno;
+
+    /*
+     * The 'align_mask' parameter of bitmap_find_next_zero_area()
+     * should be one less than a power of 2; 0 means no
+     * alignment. Adapt the 'align' value of the former allocator to
+     * fit the requirements of bitmap_find_next_zero_area()
+     */
+    align -= 1;
+
+    srcno = bitmap_find_next_zero_area(spapr->irq_map, spapr->nr_irqs, start,
+                                       count, align);
+    if (srcno == spapr->nr_irqs) {
+        return -1;
+    }
+
+    bitmap_set(spapr->irq_map, srcno, count);
+    return srcno + spapr->ics->offset;
+}
+
+static void spapr_irq_free_block(XICSFabric *xi, int irq, int num)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
+    int srcno = irq - spapr->ics->offset;
+
+    bitmap_clear(spapr->irq_map, srcno, num);
+}
+
 static void spapr_pic_print_info(InterruptStatsProvider *obj,
                                  Monitor *mon)
 {
@@ -3778,7 +3839,12 @@ static void spapr_machine_2_11_instance_options(MachineState *machine)
 
 static void spapr_machine_2_11_class_options(MachineClass *mc)
 {
-    /* Defaults for the latest behaviour inherited from the base class */
+    XICSFabricClass *xic = XICS_FABRIC_CLASS(mc);
+
+    spapr_machine_2_12_class_options(mc);
+    xic->irq_test = spapr_irq_test_2_11;
+    xic->irq_alloc_block = spapr_irq_alloc_block_2_11;
+    xic->irq_free_block = spapr_irq_free_block_2_11;
 }
 
 DEFINE_SPAPR_MACHINE(2_11, "2.11", false);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 9d21ca9bde3a..5835c694caff 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -7,6 +7,7 @@
 #include "hw/ppc/spapr_drc.h"
 #include "hw/mem/pc-dimm.h"
 #include "hw/ppc/spapr_ovec.h"
+#include "qemu/bitmap.h"
 
 struct VIOsPAPRBus;
 struct sPAPRPHBState;
@@ -78,6 +79,8 @@ struct sPAPRMachineState {
     struct VIOsPAPRBus *vio_bus;
     QLIST_HEAD(, sPAPRPHBState) phbs;
     struct sPAPRNVRAM *nvram;
+    int32_t nr_irqs;
+    unsigned long *irq_map;
     ICSState *ics;
     sPAPRRTCState rtc;
 
