>-----Original Message-----
>From: Joao Martins <joao.m.mart...@oracle.com>
>Subject: Re: [PATCH v3 01/10] vfio/iommufd: Don't fail to realize on
>IOMMU_GET_HW_INFO failure
>
>On 09/07/2024 12:45, Joao Martins wrote:
>> On 09/07/2024 09:56, Joao Martins wrote:
>>> On 09/07/2024 04:43, Duan, Zhenzhong wrote:
>>>> Hi Joao,
>>>>
>>>>> -----Original Message-----
>>>>> From: Joao Martins <joao.m.mart...@oracle.com>
>>>>> Subject: [PATCH v3 01/10] vfio/iommufd: Don't fail to realize on
>>>>> IOMMU_GET_HW_INFO failure
>>>>>
>>>>> mdevs aren't "physical" devices and when asking for backing IOMMU
>info, it
>>>>> fails the entire provisioning of the guest. Fix that by filling caps info
>>>>> when IOMMU_GET_HW_INFO succeeds plus discarding the error we
>would
>>>>> get into
>>>>> iommufd_backend_get_device_info().
>>>>>
>>>>> Cc: Zhenzhong Duan <zhenzhong.d...@intel.com>
>>>>> Fixes: 930589520128 ("vfio/iommufd: Implement
>>>>> HostIOMMUDeviceClass::realize() handler")
>>>>> Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
>>>>> ---
>>>>> hw/vfio/iommufd.c | 12 +++++-------
>>>>> 1 file changed, 5 insertions(+), 7 deletions(-)
>>>>>
>>>>> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>>>>> index c2f158e60386..a4d23f488b01 100644
>>>>> --- a/hw/vfio/iommufd.c
>>>>> +++ b/hw/vfio/iommufd.c
>>>>> @@ -631,15 +631,13 @@ static bool
>>>>> hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
>>>>>
>>>>> hiod->agent = opaque;
>>>>>
>>>>> - if (!iommufd_backend_get_device_info(vdev->iommufd, vdev-
>>devid,
>>>>> - &type, &data, sizeof(data),
>>>>> errp)) {
>>>>> - return false;
>>>>> + if (iommufd_backend_get_device_info(vdev->iommufd, vdev-
>>devid,
>>>>> + &type, &data, sizeof(data),
>>>>> NULL)) {
>>>>
>>>> This will make us miss the real error. What about bypassing host
>IOMMU device
>>>> creation for mdev as it's not "physical device", passing corresponding
>host IOMMU
>>>> device to vIOMMU make no sense.
>>>
>>> Yeap -- This was my second alternative.
>>>
>>> I can add an helper for vfio_is_mdev()) and just call
>>> iommufd_backend_get_device_info() if !vfio_is_mdev(). I am assuming
>you meant
>>> to skip the initialization of HostIOMMUDeviceCaps::caps as I think that
>>> initializing hiod still makes sense as we are still using a
>>> TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO somewhat?
>>>
>> Something like this is what I've done with this patch, see below. I think it
>> matches what you suggested? Naturally there's a precedent patch that
>introduces
>> vfio_is_mdev().
>>
>
>Sorry ignore the previous snip, it was the wrong version, see below instead.
>
>diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>index c2f158e60386..987dd9779f94 100644
>--- a/hw/vfio/iommufd.c
>+++ b/hw/vfio/iommufd.c
>@@ -631,6 +631,10 @@ static bool
>hiod_iommufd_vfio_realize(HostIOMMUDevice
>*hiod, void *opaque,
>
> hiod->agent = opaque;
>
>+ if (vfio_is_mdev(vdev)) {
>+ return true;
>+ }
>+
Not necessary to create a dummy object.
What about bypassing object_new(ops->hiod_typename) in vfio_attach_device()?
> if (!iommufd_backend_get_device_info(vdev->iommufd, vdev->devid,
> &type, &data, sizeof(data), errp)) {
> return false;
>diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>index d95aa6b65788..f092c1537999 100644
>--- a/hw/vfio/pci.c
>+++ b/hw/vfio/pci.c
>@@ -3115,7 +3115,7 @@ static void vfio_realize(PCIDevice *pdev, Error
>**errp)
>
> vfio_bars_register(vdev);
>
>- if (!pci_device_set_iommu_device(pdev, vbasedev->hiod, errp)) {
>+ if (!is_mdev && !pci_device_set_iommu_device(pdev, vbasedev->hiod,
>errp)) {
Yes.
> error_prepend(errp, "Failed to set iommu_device: ");
> goto out_teardown;
> }
>@@ -3238,7 +3238,9 @@ out_deregister:
> timer_free(vdev->intx.mmap_timer);
> }
> out_unset_idev:
>- pci_device_unset_iommu_device(pdev);
>+ if (!is_mdev) {
>+ pci_device_unset_iommu_device(pdev);
>+ }
> out_teardown:
> vfio_teardown_msi(vdev);
> vfio_bars_exit(vdev);
>@@ -3268,6 +3270,7 @@ static void vfio_exitfn(PCIDevice *pdev)
> {
> VFIOPCIDevice *vdev = VFIO_PCI(pdev);
> VFIODevice *vbasedev = &vdev->vbasedev;
>+ bool is_mdev = vfio_is_mdev(vbasedev);
>
> vfio_unregister_req_notifier(vdev);
> vfio_unregister_err_notifier(vdev);
>@@ -3283,7 +3286,9 @@ static void vfio_exitfn(PCIDevice *pdev)
> vfio_pci_disable_rp_atomics(vdev);
> vfio_bars_exit(vdev);
> vfio_migration_exit(vbasedev);
>- pci_device_unset_iommu_device(pdev);
>+ if (!is_mdev) {
>+ pci_device_unset_iommu_device(pdev);
>+ }
Yes.
Thanks
Zhenzhong
> }
