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From: Cindy Lu <lulu@redhat.com>
Date: Wed, 10 Apr 2024 13:28:39 +0800
Message-ID: <CACLfguW-o8ox5zmXdmr4Phm-8zSX3sWif8CtNDynW6kRH2fBoA@mail.gmail.com>
Subject: Re: [PATCH v2 0/1] virtio-pci: Fix the crash that the vector was used
 after released
To: lulu@redhat.com, mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org, 
	virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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Sorry, send to the wrong mail list, please ignore it

On Wed, Apr 10, 2024 at 12:35=E2=80=AFPM Cindy Lu <lulu@redhat.com> wrote:
>
> During the booting process of the Vyatta image, the behavior of the
> called function in qemu is as follows:
>
> 1. vhost_net_stop() was triggered by guest image . This will call the fun=
ction
> virtio_pci_set_guest_notifiers() with assgin=3D false, and
> virtio_pci_set_guest_notifiers(=EF=BC=89 will release the irqfd for vecto=
r 0
>
> 2. virtio_reset() was called -->set configure vector to VIRTIO_NO_VECTOR
>
> 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=3D true, so the irqfd for vector 0 is still not "init" during this=
 process
>
> 4. The system continues to boot,set the vector back to 0, and msix_fire_v=
ector_notifier() was triggered
>  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
>
> To fix this, we need to call the function "kvm_virtio_pci_vector_use_one(=
)"
> when the vector changes back from VIRTIO_NO_VECTOR.
>
> The reason that we don't need to call kvm_virtio_pci_vector_release_one w=
hile the vector changes to
> VIRTIO_NO_VECTOR is this function will called in vhost_net_stop(),
> So this step will not lost during this process.
>
> Change from V1
> 1.add the check for if using irqfd
> 2.remove the check for bool recovery, irqfd's user is enough to check sta=
tus
>
> Cindy Lu (1):
>   virtio-pci: Fix the crash that the vector was used after released.
>
>  hw/virtio/virtio-pci.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> --
> 2.43.0
>