>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Subject: Re: [PATCH v4 04/20] vfio/iommufd: Force creating nested parent
>domain
>
>On 7/30/25 12:55, Duan, Zhenzhong wrote:
>>
>>
>>> -----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/7ce1af90d5c1f418f23c9e397a16
>a3914b30f09f
>>
>> I also introduced another wrapper vfio_device_to_vfio_pci(), let me know if
>you think it's unnecessary, I'll fold it.
>
>It's good to have it if you use it everywhere:
>
>hw/vfio/device.c: if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/container.c: vbasedev_iter->type !=
>VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/container.c: vbasedev_iter->type !=
>VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/listener.c: if (vbasedev && vbasedev->type ==
>VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/listener.c: if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/iommufd.c: if (vbasedev->type == VFIO_DEVICE_TYPE_PCI) {
>hw/vfio/iommufd.c: vbasedev_tmp->type !=
>VFIO_DEVICE_TYPE_PCI) {
>
>So, I would address this cleanup separately.
OK, will send a separate one.
>
>FYI, We also have this helper :
>
>VFIODevice *vfio_get_vfio_device(Object *obj)
>{
> if (object_dynamic_cast(obj, TYPE_VFIO_PCI)) {
> return &VFIO_PCI_BASE(obj)->vbasedev;
> } else {
> return NULL;
> }
>}
I'll put new helper right under it.
Thanks
Zhenzhong
