This patch adds a new board attribute 'v-eiointc'.
A value of true enables the virt extended I/O interrupt controller.
VMs working in kvm mode have 'v-eiointc' enabled by default.

Signed-off-by: Song Gao <gaosong@loongson.cn>
---
 include/hw/loongarch/virt.h |   1 +
 target/loongarch/cpu.h      |   1 +
 hw/loongarch/virt.c         | 100 ++++++++++++++++++++++++++++++++----
 3 files changed, 93 insertions(+), 9 deletions(-)

diff --git a/include/hw/loongarch/virt.h b/include/hw/loongarch/virt.h
index 2c4f5cf9c8..8fdfacf268 100644
--- a/include/hw/loongarch/virt.h
+++ b/include/hw/loongarch/virt.h
@@ -50,6 +50,7 @@ struct LoongArchVirtMachineState {
     Notifier     machine_done;
     Notifier     powerdown_notifier;
     OnOffAuto    acpi;
+    OnOffAuto    veiointc;
     char         *oem_id;
     char         *oem_table_id;
     DeviceState  *acpi_ged;
diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
index 41b8e6d96d..6c41fafb70 100644
--- a/target/loongarch/cpu.h
+++ b/target/loongarch/cpu.h
@@ -36,6 +36,7 @@
 #define CPUNAME_REG             0x20
 #define MISC_FUNC_REG           0x420
 #define IOCSRM_EXTIOI_EN        48
+#define IOCSRM_EXTIOI_INT_ENCODE 49
 
 #define IOCSR_MEM_SIZE          0x428
 
diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 95f9ed5cae..e7edc6c9f9 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -11,6 +11,7 @@
 #include "hw/boards.h"
 #include "hw/char/serial.h"
 #include "sysemu/kvm.h"
+#include "sysemu/tcg.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/qtest.h"
 #include "sysemu/runstate.h"
@@ -47,6 +48,31 @@
 #include "hw/block/flash.h"
 #include "qemu/error-report.h"
 
+static bool virt_is_veiointc_enabled(LoongArchVirtMachineState *lvms)
+{
+    if (lvms->veiointc == ON_OFF_AUTO_OFF) {
+        return false;
+    }
+    return true;
+}
+
+static void virt_get_veiointc(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
+{
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(obj);
+    OnOffAuto veiointc = lvms->veiointc;
+
+    visit_type_OnOffAuto(v, name, &veiointc, errp);
+}
+
+static void virt_set_veiointc(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
+{
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(obj);
+
+    visit_type_OnOffAuto(v, name, &lvms->veiointc, errp);
+}
+
 static PFlashCFI01 *virt_flash_create1(LoongArchVirtMachineState *lvms,
                                        const char *name,
                                        const char *alias_prop_name)
@@ -724,9 +750,16 @@ static void virt_irq_init(LoongArchVirtMachineState *lvms)
     /* Create EXTIOI device */
     extioi = qdev_new(TYPE_LOONGARCH_EXTIOI);
     qdev_prop_set_uint32(extioi, "num-cpu", ms->smp.cpus);
+    if (virt_is_veiointc_enabled(lvms)) {
+        qdev_prop_set_bit(extioi, "has-virtualization-extension", true);
+    }
     sysbus_realize_and_unref(SYS_BUS_DEVICE(extioi), &error_fatal);
     memory_region_add_subregion(&lvms->system_iocsr, APIC_BASE,
-                   sysbus_mmio_get_region(SYS_BUS_DEVICE(extioi), 0));
+                    sysbus_mmio_get_region(SYS_BUS_DEVICE(extioi), 0));
+    if (virt_is_veiointc_enabled(lvms)) {
+        memory_region_add_subregion(&lvms->system_iocsr, EXTIOI_VIRT_BASE,
+                    sysbus_mmio_get_region(SYS_BUS_DEVICE(extioi), 1));
+    }
 
     /*
      * connect ext irq to the cpu irq
@@ -833,33 +866,74 @@ static void virt_firmware_init(LoongArchVirtMachineState *lvms)
     }
 }
 
-
 static void virt_iocsr_misc_write(void *opaque, hwaddr addr,
                                   uint64_t val, unsigned size)
 {
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(opaque);
+    uint64_t features;
+
+    switch (addr) {
+    case MISC_FUNC_REG:
+        if (!virt_is_veiointc_enabled(lvms)) {
+            return;
+        }
+
+        features = address_space_ldl(&lvms->as_iocsr,
+                                     EXTIOI_VIRT_BASE + EXTIOI_VIRT_CONFIG,
+                                     MEMTXATTRS_UNSPECIFIED, NULL);
+        if (val & BIT_ULL(IOCSRM_EXTIOI_EN)) {
+            features |= BIT(EXTIOI_ENABLE);
+        }
+        if (val & BIT_ULL(IOCSRM_EXTIOI_INT_ENCODE)) {
+            features |= BIT(EXTIOI_ENABLE_INT_ENCODE);
+        }
+
+        address_space_stl(&lvms->as_iocsr,
+                          EXTIOI_VIRT_BASE + EXTIOI_VIRT_CONFIG,
+                          features, MEMTXATTRS_UNSPECIFIED, NULL);
+    }
 }
 
 static uint64_t virt_iocsr_misc_read(void *opaque, hwaddr addr, unsigned size)
 {
-    uint64_t ret;
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(opaque);
+    uint64_t ret = 0;
+    int features;
 
     switch (addr) {
     case VERSION_REG:
-        return 0x11ULL;
+        ret = 0x11ULL;
+        break;
     case FEATURE_REG:
         ret = BIT(IOCSRF_MSI) | BIT(IOCSRF_EXTIOI) | BIT(IOCSRF_CSRIPI);
         if (kvm_enabled()) {
             ret |= BIT(IOCSRF_VM);
         }
-        return ret;
+        break;
     case VENDOR_REG:
-        return 0x6e6f73676e6f6f4cULL; /* "Loongson" */
+        ret = 0x6e6f73676e6f6f4cULL; /* "Loongson" */
+        break;
     case CPUNAME_REG:
-        return 0x303030354133ULL;     /* "3A5000" */
+        ret = 0x303030354133ULL;     /* "3A5000" */
+        break;
     case MISC_FUNC_REG:
-        return BIT_ULL(IOCSRM_EXTIOI_EN);
+        if (!virt_is_veiointc_enabled(lvms)) {
+            ret |= BIT_ULL(IOCSRM_EXTIOI_EN);
+            break;
+        }
+
+        features = address_space_ldl(&lvms->as_iocsr,
+                                     EXTIOI_VIRT_BASE + EXTIOI_VIRT_CONFIG,
+                                     MEMTXATTRS_UNSPECIFIED, NULL);
+        if (features & BIT(EXTIOI_ENABLE)) {
+            ret |= BIT_ULL(IOCSRM_EXTIOI_EN);
+        }
+        if (features & BIT(EXTIOI_ENABLE_INT_ENCODE)) {
+            ret |= BIT_ULL(IOCSRM_EXTIOI_INT_ENCODE);
+        }
     }
-    return 0ULL;
+
+    return ret;
 }
 
 static const MemoryRegionOps virt_iocsr_misc_ops = {
@@ -1045,6 +1119,9 @@ static void virt_initfn(Object *obj)
 {
     LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(obj);
 
+    if (tcg_enabled()) {
+        lvms->veiointc = ON_OFF_AUTO_OFF;
+    }
     lvms->acpi = ON_OFF_AUTO_AUTO;
     lvms->oem_id = g_strndup(ACPI_BUILD_APPNAME6, 6);
     lvms->oem_table_id = g_strndup(ACPI_BUILD_APPNAME8, 8);
@@ -1231,6 +1308,11 @@ static void virt_class_init(ObjectClass *oc, void *data)
         NULL, NULL);
     object_class_property_set_description(oc, "acpi",
         "Enable ACPI");
+    object_class_property_add(oc, "v-eiointc", "OnOffAuto",
+        virt_get_veiointc, virt_set_veiointc,
+        NULL, NULL);
+    object_class_property_set_description(oc, "v-eiointc",
+                            "Enable Virt Extend I/O Interrupt Controller.");
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_RAMFB_DEVICE);
 #ifdef CONFIG_TPM
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_TPM_TIS_SYSBUS);
-- 
2.34.1