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An HVM guest with linux stubdomain 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 stubdomain 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() Have pcifront_detach_devices() special-case state Initialised and call pcifront_connect_and_init_dma(). Don't use pcifront_try_connect() because that sets the xenbus state which may throw off the backend. After connecting, skip the remainder of detach_devices since none have been initialized yet. When the backend switches to Reconfigured, pcifront_attach_devices() will pick them up again. Signed-off-by: Jason Andryuk <jandryuk@gmail.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20220829151536.8578-1-jandryuk@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.