When disabling MSI/X interrupts the disable functions will leave the
device in INTx mode (when available). This matches how hardware
operates, INTx is enabled unless MSI/X is enabled (DisINTx is handled
separately). Therefore when we really want to disable all interrupts,
such as when removing the device, and we start with the device in
MSI/X mode, we need to pass through INTx on our way to being
completely quiesced.
In well behaved situations, the guest driver will have shutdown the
device and it will start vfio_exitfn() in INTx mode, producing the
desired result. If hot-unplug causes the guest to crash, we may get
the device in MSI/X state, which will leave QEMU with a bogus handler
installed.
Fix this by re-ordering our disable routine so that it should always
finish in VFIO_INT_NONE state, which is what all callers expect.
Signed-off-by: Alex Williamson <alex.william...@redhat.com>
---
hw/vfio/pci.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index b6703c7..014a92c 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2129,16 +2129,19 @@ static void vfio_pci_write_config(PCIDevice *pdev,
uint32_t addr,
*/
static void vfio_disable_interrupts(VFIOPCIDevice *vdev)
{
- switch (vdev->interrupt) {
- case VFIO_INT_INTx:
- vfio_disable_intx(vdev);
- break;
- case VFIO_INT_MSI:
- vfio_disable_msi(vdev);
- break;
- case VFIO_INT_MSIX:
+ /*
+ * More complicated than it looks. Disabling MSI/X transitions the
+ * device to INTx mode (if supported). Therefore we need to first
+ * disable MSI/X and then cleanup by disabling INTx.
+ */
+ if (vdev->interrupt == VFIO_INT_MSIX) {
vfio_disable_msix(vdev);
- break;
+ } else if (vdev->interrupt == VFIO_INT_MSI) {
+ vfio_disable_msi(vdev);
+ }
+
+ if (vdev->interrupt == VFIO_INT_INTx) {
+ vfio_disable_intx(vdev);
}
}
