On 6/20/25 9:17 AM, Zhenzhong Duan wrote:
> Call pci_device_get_viommu_cap() to get if vIOMMU supports VIOMMU_CAP_STAGE1,
> if yes, create nested parent domain which could be reused by vIOMMU to create
could? Is there a choice?
> nested domain.
I would add in the commit msg that it is safe because
hw_caps & VIOMMU_CAP_STAGE1 cannot be set yet because s->flts is forbidden
until last patch of the series.
Eric
>
> Suggested-by: Nicolin Chen <nicol...@nvidia.com>
> Suggested-by: Yi Liu <yi.l....@intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
> ---
> hw/vfio/iommufd.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index d3efef71af..83a632bdee 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -20,6 +20,7 @@
> #include "trace.h"
> #include "qapi/error.h"
> #include "system/iommufd.h"
> +#include "hw/iommu.h"
> #include "hw/qdev-core.h"
> #include "hw/vfio/vfio-cpr.h"
> #include "system/reset.h"
> @@ -352,6 +353,19 @@ 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 (vbasedev->type == VFIO_DEVICE_TYPE_PCI) {
> + VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice,
> vbasedev);
> +
> + hw_caps = pci_device_get_viommu_cap(&vdev->pdev);
> + if (hw_caps & VIOMMU_CAP_STAGE1) {
> + flags |= IOMMU_HWPT_ALLOC_NEST_PARENT;
> + }
> + }
> +
> if (!iommufd_backend_alloc_hwpt(iommufd, vbasedev->devid,
> container->ioas_id, flags,
> IOMMU_HWPT_DATA_NONE, 0, NULL,
