[RFC 0/2] disable the configuration interrupt for the unsupported device

[Cindy Lu <lulu@redhat.com>]

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we need a crash in Non-standard image, here is the jira for this https://issues.redhat.com/browse/RHEL-28522
The root cause of the issue is that an IRQFD was used without initialization..

During the booting process of the Vyatta image, the behavior of the called function in qemu is as follows:

1. vhost_net_stop() was called, this will call the function
virtio_pci_set_guest_notifiers() with assgin= false, and
virtio_pci_set_guest_notifiers(） will release the irqfd for vector 0

2. virtio_reset() was called -->set configure vector to VIRTIO_NO_VECTORt

3.vhost_net_start() was called (at this time the configure vector is
still VIRTIO_NO_VECTOR) and call virtio_pci_set_guest_notifiers() with
assgin= true, so the irqfd for vector 0 was not "init" during this process

4. The system continues to boot and msix_fire_vector_notifier() was
called unmask the vector 0 and then met the crash
[msix_fire_vector_notifier] 112 called vector 0 is_masked 1
[msix_fire_vector_notifier] 112 called vector 0 is_masked 0

The reason for not reproducing in RHEL/fedora guest image is because
REHL/Fedora doesn't have the behavior of calling vhost_net_stop and then virtio_reset, and also won't call msix_fire_vector_notifier for vector 0 during system boot.

The reason for not reproducing before configure interrupt support is because
vector 0 is for configure interrupt,  before the support for configure interrupts, the notifier process will not handle vector 0.

For the device Vyatta using, it doesn't support configure interrupts at all, So we plan to disable the configure interrupts in unsupported device

Signed-off-by: Cindy Lu <lulu@redhat.com>

Cindy Lu (2):
  virtio-net: disable the configure interrupt for not support device
  virtio-pci: check if the configure interrupt enable

 hw/net/virtio-net.c        |  5 ++++-
 hw/virtio/virtio-pci.c     | 41 +++++++++++++++++++++-----------------
 hw/virtio/virtio.c         |  1 +
 include/hw/virtio/virtio.h |  1 +
 4 files changed, 29 insertions(+), 19 deletions(-)

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