Re: [PATCH v4 02/12] vfio/iommufd: Don't initialize nor set a HOST_IOMMU_DEVICE with mdev

[Cédric Le Goater]

On 7/12/24 13:46, Joao Martins wrote:

mdevs aren't "physical" devices and when asking for backing IOMMU info, it
fails the entire provisioning of the guest. Fix that by skipping
HostIOMMUDevice initialization in the presence of mdevs, and skip setting
an iommu device when it is known to be an mdev.

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/common.c |  4 ++++
  hw/vfio/pci.c    | 10 +++++++---
  2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 7cdb969fd396..b0beed44116e 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1556,6 +1556,10 @@ bool vfio_attach_device(char *name, VFIODevice *vbasedev,
          return false;
      }

+ if (vbasedev->mdev) {

+        return true;
+    }
+
      hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
      if (!HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev, errp)) {
          object_unref(hiod);
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 585f23a18406..3fc72e898a25 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3116,7 +3116,7 @@ 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)) {

let's use vbasedev->mdev instead.


Thanks,

C.

          error_prepend(errp, "Failed to set iommu_device: ");
          goto out_teardown;
      }
@@ -3239,7 +3239,9 @@ 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);
@@ -3284,7 +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 (!vbasedev->mdev) {
+        pci_device_unset_iommu_device(pdev);
+    }
  }

static void vfio_pci_reset(DeviceState *dev)