RE: [PATCH v3 01/10] vfio/iommufd: Don't fail to realize on IOMMU_GET_HW_INFO failure

[Duan, Zhenzhong]

Hi Joao,

>-----Original Message-----
>From: Joao Martins <joao.m.martins@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.duan@intel.com>
>Fixes: 930589520128 ("vfio/iommufd: Implement
>HostIOMMUDeviceClass::realize() handler")
>Signed-off-by: Joao Martins <joao.m.martins@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.

Thanks
Zhenzhong

>+        hiod->name = g_strdup(vdev->name);
>+        caps->type = type;
>+        caps->aw_bits = vfio_device_get_aw_bits(vdev);
>     }
>
>-    hiod->name = g_strdup(vdev->name);
>-    caps->type = type;
>-    caps->aw_bits = vfio_device_get_aw_bits(vdev);
>-
>     return true;
> }
>
>--
>2.17.2