>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Subject: Re: [PATCH v4 04/20] vfio/iommufd: Force creating nested parent
>domain
>
>On 7/29/25 11:20, Zhenzhong Duan wrote:
>> 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.
>>
>> It is safe because hw_caps & VIOMMU_CAP_HW_NESTED cannot be set yet
>because
>> s->flts is forbidden 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>
>> Reviewed-by: Eric Auger <eric.au...@redhat.com>
>> ---
>> hw/vfio/iommufd.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>> index 48c590b6a9..61a548f13f 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"
>> @@ -379,6 +380,19 @@ 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_HW_NESTED) {
>> + flags |= IOMMU_HWPT_ALLOC_NEST_PARENT;
>> + }
>> + }
>>
>
>Could you please add a wrapper for the above ? Something like :
>
>static bool vfio_device_viommu_get_nested(VFIODevice *vbasedev)
>{
> if (vbasedev->type == VFIO_DEVICE_TYPE_PCI) {
> VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice,
>vbasedev);
>
> return !!(pci_device_get_viommu_cap(&vdev->pdev) &
>VIOMMU_CAP_HW_NESTED);
> }
> return false;
>}
>
>May be this routine belongs to hw/vfio/device.c.
Done, see
https://github.com/yiliu1765/qemu/commit/7ce1af90d5c1f418f23c9e397a16a3914b30f09f
I also introduced another wrapper vfio_device_to_vfio_pci(), let me know if you
think it's unnecessary, I'll fold it.
Thanks
Zhenzhong
