hw/arm/virt: add ITS support in virt GIC

Included creation of ITS as part of virt platform GIC
initialization. This Emulated ITS model now co-exists with kvm
ITS and is enabled in absence of kvm irq kernel support in a
platform.

Signed-off-by: Shashi Mallela <shashi.mallela@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20210910143951.92242-9-shashi.mallela@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/virt.c

@@ -584,6 +584,12 @@ static void create_its(VirtMachineState *vms)
     const char *itsclass = its_class_name();
     DeviceState *dev;
 
+    if (!strcmp(itsclass, "arm-gicv3-its")) {
+        if (!vms->tcg_its) {
+            itsclass = NULL;
+        }
+    }
+
     if (!itsclass) {
         /* Do nothing if not supported */
         return;
@@ -621,7 +627,7 @@ static void create_v2m(VirtMachineState *vms)
     vms->msi_controller = VIRT_MSI_CTRL_GICV2M;
 }
 
-static void create_gic(VirtMachineState *vms)
+static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
 {
     MachineState *ms = MACHINE(vms);
     /* We create a standalone GIC */
@@ -655,6 +661,14 @@ static void create_gic(VirtMachineState *vms)
                              nb_redist_regions);
         qdev_prop_set_uint32(vms->gic, "redist-region-count[0]", redist0_count);
 
+        if (!kvm_irqchip_in_kernel()) {
+            if (vms->tcg_its) {
+                object_property_set_link(OBJECT(vms->gic), "sysmem",
+                                         OBJECT(mem), &error_fatal);
+                qdev_prop_set_bit(vms->gic, "has-lpi", true);
+            }
+        }
+
         if (nb_redist_regions == 2) {
             uint32_t redist1_capacity =
                     vms->memmap[VIRT_HIGH_GIC_REDIST2].size / GICV3_REDIST_SIZE;
@@ -2039,7 +2053,7 @@ static void machvirt_init(MachineState *machine)
 
     virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
 
-    create_gic(vms);
+    create_gic(vms, sysmem);
 
     virt_cpu_post_init(vms, sysmem);
 
@@ -2742,6 +2756,12 @@ static void virt_instance_init(Object *obj)
     } else {
         /* Default allows ITS instantiation */
         vms->its = true;
+
+        if (vmc->no_tcg_its) {
+            vms->tcg_its = false;
+        } else {
+            vms->tcg_its = true;
+        }
     }
 
     /* Default disallows iommu instantiation */
@@ -2791,8 +2811,13 @@ DEFINE_VIRT_MACHINE_AS_LATEST(6, 2)
 
 static void virt_machine_6_1_options(MachineClass *mc)
 {
+    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
+
     virt_machine_6_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
+
+    /* qemu ITS was introduced with 6.2 */
+    vmc->no_tcg_its = true;
 }
 DEFINE_VIRT_MACHINE(6, 1)
 

include/hw/arm/virt.h

@@ -120,6 +120,7 @@ struct VirtMachineClass {
     MachineClass parent;
     bool disallow_affinity_adjustment;
     bool no_its;
+    bool no_tcg_its;
     bool no_pmu;
     bool claim_edge_triggered_timers;
     bool smbios_old_sys_ver;
@@ -141,6 +142,7 @@ struct VirtMachineState {
     bool highmem;
     bool highmem_ecam;
     bool its;
+    bool tcg_its;
     bool virt;
     bool ras;
     bool mte;

target/arm/kvm_arm.h

@@ -525,8 +525,8 @@ static inline const char *its_class_name(void)
         /* KVM implementation requires this capability */
         return kvm_direct_msi_enabled() ? "arm-its-kvm" : NULL;
     } else {
-        /* Software emulation is not implemented yet */
+        /* Software emulation based model */
-        return NULL;
+        return "arm-gicv3-its";
     }
 }