Re: [PATCH] vfio/pci: Remove vfio_detach_device from vfio_realize error path

[Cédric Le Goater]

On 10/11/23 22:09, Eric Auger wrote:

In vfio_realize, on the error path, we currently call
vfio_detach_device() after a successful vfio_attach_device.
While this looks natural, vfio_instance_finalize also induces
a vfio_detach_device(), and it seems to be the right place
instead as other resources are released there which happen
to be a prerequisite to a successful UNSET_CONTAINER.

So let's rely on the finalize vfio_detach_device call to free
all the relevant resources.

Fixes: a28e06621170 ("vfio/pci: Introduce vfio_[attach/detach]_device")
Reported-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
Signed-off-by: Eric Auger <eric.au...@redhat.com>

---

This applies on top of vfio-next

Applied to vfio-next.

Note I am not sure the SHA1 of
vfio/pci: Introduce vfio_[attach/detach]_device
is stable.

It should if I only rebase on master. If I need to re-apply, I will drop
the Fixes tag.

Thanks,

C.

---
  hw/vfio/pci.c | 16 +++++++---------
  1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 40ae46266e..6e3f6aba28 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3115,7 +3115,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      vfio_populate_device(vdev, &err);
      if (err) {
          error_propagate(errp, err);
-        goto out_detach;
+        goto error;
      }

/* Get a copy of config space */

@@ -3125,7 +3125,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      if (ret < (int)MIN(pci_config_size(&vdev->pdev), vdev->config_size)) {
          ret = ret < 0 ? -errno : -EFAULT;
          error_setg_errno(errp, -ret, "failed to read device config space");
-        goto out_detach;
+        goto error;
      }

/* vfio emulates a lot for us, but some bits need extra love */

@@ -3144,7 +3144,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      if (vdev->vendor_id != PCI_ANY_ID) {
          if (vdev->vendor_id >= 0xffff) {
              error_setg(errp, "invalid PCI vendor ID provided");
-            goto out_detach;
+            goto error;
          }
          vfio_add_emulated_word(vdev, PCI_VENDOR_ID, vdev->vendor_id, ~0);
          trace_vfio_pci_emulated_vendor_id(vbasedev->name, vdev->vendor_id);
@@ -3155,7 +3155,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      if (vdev->device_id != PCI_ANY_ID) {
          if (vdev->device_id > 0xffff) {
              error_setg(errp, "invalid PCI device ID provided");
-            goto out_detach;
+            goto error;
          }
          vfio_add_emulated_word(vdev, PCI_DEVICE_ID, vdev->device_id, ~0);
          trace_vfio_pci_emulated_device_id(vbasedev->name, vdev->device_id);
@@ -3166,7 +3166,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      if (vdev->sub_vendor_id != PCI_ANY_ID) {
          if (vdev->sub_vendor_id > 0xffff) {
              error_setg(errp, "invalid PCI subsystem vendor ID provided");
-            goto out_detach;
+            goto error;
          }
          vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_VENDOR_ID,
                                 vdev->sub_vendor_id, ~0);
@@ -3177,7 +3177,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      if (vdev->sub_device_id != PCI_ANY_ID) {
          if (vdev->sub_device_id > 0xffff) {
              error_setg(errp, "invalid PCI subsystem device ID provided");
-            goto out_detach;
+            goto error;
          }
          vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_ID, vdev->sub_device_id, 
~0);
          trace_vfio_pci_emulated_sub_device_id(vbasedev->name,
@@ -3210,7 +3210,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      vfio_msix_early_setup(vdev, &err);
      if (err) {
          error_propagate(errp, err);
-        goto out_detach;
+        goto error;
      }

vfio_bars_register(vdev);

@@ -3326,8 +3326,6 @@ out_deregister:
  out_teardown:
      vfio_teardown_msi(vdev);
      vfio_bars_exit(vdev);
-out_detach:
-    vfio_detach_device(vbasedev);
  error:
      error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->name);
  }