hw/i386: Add a default_bus_bypass_iommu pc machine option

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>
Message-Id: <1625748919-52456-5-git-send-email-wangxingang5@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index f4c7a78362..c2b9d62a35 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1524,6 +1524,21 @@ 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)
@@ -1623,6 +1638,7 @@ 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);
@@ -1747,6 +1763,10 @@ 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 0f37cf056a..ab5a47aff5 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -65,6 +65,8 @@ 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);
 }