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

[Paolo Bonzini]

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 <pbonz...@redhat.com>
---
 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