From: Xingang Wang <wangxingang5@huawei.com>

Add a default_bus_bypass_iommu pc machine option to enable/disable
bypass_iommu for default root bus. The option is disabled by default
and can be enabled with:
$QEMU -machine q35,default_bus_bypass_iommu=true

Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
---
 hw/i386/pc.c         | 20 ++++++++++++++++++++
 hw/pci-host/q35.c    |  2 ++
 include/hw/i386/pc.h |  1 +
 3 files changed, 23 insertions(+)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 8e1220db72..257d70f6e9 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1522,6 +1522,21 @@ static void pc_machine_set_hpet(Object *obj, bool value, Error **errp)
     pcms->hpet_enabled = value;
 }
 
+static bool pc_machine_get_default_bus_bypass_iommu(Object *obj, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    return pcms->default_bus_bypass_iommu;
+}
+
+static void pc_machine_set_default_bus_bypass_iommu(Object *obj, bool value,
+                                                    Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    pcms->default_bus_bypass_iommu = value;
+}
+
 static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
                                             const char *name, void *opaque,
                                             Error **errp)
@@ -1621,6 +1636,7 @@ static void pc_machine_initfn(Object *obj)
 #ifdef CONFIG_HPET
     pcms->hpet_enabled = true;
 #endif
+    pcms->default_bus_bypass_iommu = false;
 
     pc_system_flash_create(pcms);
     pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
@@ -1745,6 +1761,10 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     object_class_property_add_bool(oc, "hpet",
         pc_machine_get_hpet, pc_machine_set_hpet);
 
+    object_class_property_add_bool(oc, "default_bus_bypass_iommu",
+        pc_machine_get_default_bus_bypass_iommu,
+        pc_machine_set_default_bus_bypass_iommu);
+
     object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
         pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
         NULL, NULL);
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 2eb729dff5..826a05d7f3 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -64,6 +64,8 @@ static void q35_host_realize(DeviceState *dev, Error **errp)
                                 s->mch.address_space_io,
                                 0, TYPE_PCIE_BUS);
     PC_MACHINE(qdev_get_machine())->bus = pci->bus;
+    pci->bypass_iommu =
+        PC_MACHINE(qdev_get_machine())->default_bus_bypass_iommu;
     qdev_realize(DEVICE(&s->mch), BUS(pci->bus), &error_fatal);
 }
 
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 87294f2632..fd741119fa 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -44,6 +44,7 @@ typedef struct PCMachineState {
     bool sata_enabled;
     bool pit_enabled;
     bool hpet_enabled;
+    bool default_bus_bypass_iommu;
     uint64_t max_fw_size;
 
     /* NUMA information: */
-- 
2.19.1