Re: [PATCH v4 3/5] vfio/pci: Disable INTx in vfio_realize error path

[Cédric Le Goater]

On 6/29/23 13:24, Joao Martins wrote:
On 29/06/2023 09:40, Zhenzhong Duan wrote:
When vfio realize fails, INTx isn't disabled if it has been enabled.
This may confuse host side with unhandled interrupt report.
Add a new label to be used for vfio_intx_enable() failed case.

Fixes: a9994687cb9b ("vfio/display: core & wireup")
Fixes: b290659fc3dd ("hw/vfio/display: add ramfb support")
Fixes: c62a0c7ce34e ("vfio/display: add xres + yres properties")

Sounds to me the correct Fixes tag is the same as first patch i.e.:

Fixes: c5478fea27ac ("vfio/pci: Respond to KVM irqchip change notifier")

Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>

Looks good, but see some clarifications below.

---
  hw/vfio/pci.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index ab6645ba60af..54a8179d1c64 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3167,7 +3167,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
          kvm_irqchip_add_change_notifier(&vdev->irqchip_change_notifier);
          ret = vfio_intx_enable(vdev, errp);
          if (ret) {
-            goto out_deregister;
+            goto out_intx_disable;
          }
      }
  
@@ -3220,6 +3220,8 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      return;
  
  out_deregister:
+    vfio_disable_interrupts(vdev);

You are calling vfio_disable_interrupts() when what you want is
vfio_intx_disable() ? But I guess your thinking was to call
vfio_disable_interrupt() which eventually calls vfio_intx_disable() in case INTx
was really setup, thus saving the duplicated check. The MSIx/MSI in realize() I
don't think they will be enabled at this point. Let me know if I misunderstood.

+out_intx_disable:

Maybe 'out_intx_teardown' or 'out_intx_deregister' because you are not really
disabling INTx.

or simply extract from vfio_disable_interrupts() :
 
    if (vdev->interrupt == VFIO_INT_INTx) {
        vfio_intx_disable(vdev);
    }

and add the above code before cleaning up the intx routing
notifier without any new goto labels.

Thanks,

C.



      pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
      if (vdev->irqchip_change_notifier.notify) {
          kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);