Re: [Qemu-devel] [PATCH] virtio-pci: fix MSI memory region use after tree

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jul 04, 2014 at 11:43:49AM +0200, Paolo Bonzini wrote:
> After memory region QOMification QEMU is stricter in detecting
> wrong usage of the memory region API.  Here it detected a
> memory_region_destroy done before the corresponding
> memory_region_del_subregion; the memory_region_destroy is
> done by msix_uninit_exclusive_bar, the memory_region_del_subregion
> is done by the PCI core's pci_unregister_io_regions before
> pc->exit is called.
> 
> The misuse caused an assertion when hot-unplugging virtio
> devices.  Using the API correctly fixes the assertion.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Applied, thanks!
I also added some historical context in the comments
(the API misuse was introduced in 06a1307379fcd6c551185ad87679cd7ed896b9ea)


> ---
>  hw/virtio/virtio-pci.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 3c42cda..ecb2097 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1003,11 +1003,9 @@ static void virtio_pci_device_plugged(DeviceState *d)
>  
>  static void virtio_pci_device_unplugged(DeviceState *d)
>  {
> -    PCIDevice *pci_dev = PCI_DEVICE(d);
>      VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
>  
>      virtio_pci_stop_ioeventfd(proxy);
> -    msix_uninit_exclusive_bar(pci_dev);
>  }
>  
>  static int virtio_pci_init(PCIDevice *pci_dev)
> @@ -1024,6 +1022,8 @@ static int virtio_pci_init(PCIDevice *pci_dev)
>  static void virtio_pci_exit(PCIDevice *pci_dev)
>  {
>      VirtIOPCIProxy *proxy = VIRTIO_PCI(pci_dev);
> +
> +    msix_uninit_exclusive_bar(pci_dev);
>      memory_region_destroy(&proxy->bar);
>  }
>  
> -- 
> 1.9.3