hw/arm/virt: Add default_bus_bypass_iommu machine option

Add a default_bus_bypass_iommu machine option to enable/disable
bypass_iommu for default root bus. The option is disabled by
default and can be enabled with:
$QEMU -machine virt,iommu=smmuv3,default_bus_bypass_iommu=true

Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
Message-Id: <1625748919-52456-4-git-send-email-wangxingang5@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/arm/virt.c

@@ -1367,6 +1367,7 @@ static void create_pcie(VirtMachineState *vms)
     }
 
     pci = PCI_HOST_BRIDGE(dev);
+    pci->bypass_iommu = vms->default_bus_bypass_iommu;
     vms->bus = pci->bus;
     if (vms->bus) {
         for (i = 0; i < nb_nics; i++) {
@@ -2322,6 +2323,21 @@ static void virt_set_iommu(Object *obj, const char *value, Error **errp)
     }
 }
 
+static bool virt_get_default_bus_bypass_iommu(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->default_bus_bypass_iommu;
+}
+
+static void virt_set_default_bus_bypass_iommu(Object *obj, bool value,
+                                              Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->default_bus_bypass_iommu = value;
+}
+
 static CpuInstanceProperties
 virt_cpu_index_to_props(MachineState *ms, unsigned cpu_index)
 {
@@ -2661,6 +2677,13 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
                                           "Set the IOMMU type. "
                                           "Valid values are none and smmuv3");
 
+    object_class_property_add_bool(oc, "default_bus_bypass_iommu",
+                                   virt_get_default_bus_bypass_iommu,
+                                   virt_set_default_bus_bypass_iommu);
+    object_class_property_set_description(oc, "default_bus_bypass_iommu",
+                                          "Set on/off to enable/disable "
+                                          "bypass_iommu for default root bus");
+
     object_class_property_add_bool(oc, "ras", virt_get_ras,
                                    virt_set_ras);
     object_class_property_set_description(oc, "ras",
@@ -2728,6 +2751,9 @@ static void virt_instance_init(Object *obj)
     /* Default disallows iommu instantiation */
     vms->iommu = VIRT_IOMMU_NONE;
 
+    /* The default root bus is attached to iommu by default */
+    vms->default_bus_bypass_iommu = false;
+
     /* Default disallows RAS instantiation */
     vms->ras = false;
 

include/hw/arm/virt.h

@@ -147,6 +147,7 @@ struct VirtMachineState {
     OnOffAuto acpi;
     VirtGICType gic_version;
     VirtIOMMUType iommu;
+    bool default_bus_bypass_iommu;
     VirtMSIControllerType msi_controller;
     uint16_t virtio_iommu_bdf;
     struct arm_boot_info bootinfo;