On Aug 29, 2022, at 11:16 AM, Jason Andryuk <jandryuk@xxxxxxxxx> wrote: > > An HVM guest with linux stubdom and 2 PCI devices failed to start as > libxl timed out waiting for the PCI devices to be added. It happens > intermittently but with some regularity. libxl wrote the two xenstore > entries for the devices, but then timed out waiting for backend state 4 > (Connected) - the state stayed at 7 (Reconfiguring). (PCI passthrough > to an HVM with stubdomain is PV passthrough to the stubdomain and then > HVM passthrough with the QEMU inside the stubdomain.) > > The stubdom kernel never printed "pcifront pci-0: Installing PCI > frontend", so it seems to have missed state 4 which would have > called pcifront_try_connect -> pcifront_connect_and_init_dma Is there a state machine doc/flowchart for LibXL and Xen PCI device passthrough to Linux? This would be a valuable addition to Xen's developer docs, even as a whiteboard photo in this thread. Rich
