[PATCH v5 05/21] vfio/iommufd: Force creating nested parent domain

[Zhenzhong Duan]

Call pci_device_get_viommu_cap() to get if vIOMMU supports VIOMMU_CAP_HW_NESTED,
if yes, create nested parent domain which could be reused by vIOMMU to create
nested domain.

Introduce helper vfio_device_viommu_get_nested to facilitate this
implementation.

It is safe because even if VIOMMU_CAP_HW_NESTED is returned, s->flts is
forbidden and VFIO device fails in set_iommu_device() call, until we support
passthrough device with x-flts=on.

Suggested-by: Nicolin Chen <nicol...@nvidia.com>
Suggested-by: Yi Liu <yi.l....@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 include/hw/vfio/vfio-device.h |  2 ++
 hw/vfio/device.c              | 12 ++++++++++++
 hw/vfio/iommufd.c             |  8 ++++++++
 3 files changed, 22 insertions(+)

diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 6e4d5ccdac..ecd82c16c7 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -257,6 +257,8 @@ void vfio_device_prepare(VFIODevice *vbasedev, 
VFIOContainerBase *bcontainer,
 
 void vfio_device_unprepare(VFIODevice *vbasedev);
 
+bool vfio_device_viommu_get_nested(VFIODevice *vbasedev);
+
 int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info);
 int vfio_device_get_region_info_type(VFIODevice *vbasedev, uint32_t type,
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index 08f12ac31f..3eeb71bd51 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -23,6 +23,7 @@
 
 #include "hw/vfio/vfio-device.h"
 #include "hw/vfio/pci.h"
+#include "hw/iommu.h"
 #include "hw/hw.h"
 #include "trace.h"
 #include "qapi/error.h"
@@ -504,6 +505,17 @@ void vfio_device_unprepare(VFIODevice *vbasedev)
     vbasedev->bcontainer = NULL;
 }
 
+bool vfio_device_viommu_get_nested(VFIODevice *vbasedev)
+{
+    VFIOPCIDevice *vdev = vfio_pci_from_vfio_device(vbasedev);
+
+    if (vdev) {
+        return !!(pci_device_get_viommu_cap(&vdev->pdev) &
+                  VIOMMU_CAP_HW_NESTED);
+    }
+    return false;
+}
+
 /*
  * Traditional ioctl() based io
  */
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 8c27222f75..e503c232e1 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -379,6 +379,14 @@ static bool iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
         flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
     }
 
+    /*
+     * If vIOMMU supports stage-1 translation, force to create nested parent
+     * domain which could be reused by vIOMMU to create nested domain.
+     */
+    if (vfio_device_viommu_get_nested(vbasedev)) {
+        flags |= IOMMU_HWPT_ALLOC_NEST_PARENT;
+    }
+
     if (cpr_is_incoming()) {
         hwpt_id = vbasedev->cpr.hwpt_id;
         goto skip_alloc;
-- 
2.47.1