Featured content is also available via:

spapr_pci: fix multifunction hotplug

Enterprise / Virtualization / QEMU - Michael Roth [linux.vnet.ibm.com] - 15 March 2016 17:55 UTC

Since 3f1e147, QEMU has adopted a convention of supporting function hotplug by deferring hotplug events until func 0 is hotplugged. This is likely how management tools like libvirt would expose such support going forward.

Since sPAPR guests rely on per-func events rather than slot-based, our protocol has been to hotplug func 0 *first* to avoid cases where devices appear within guests without func 0 present to avoid undefined behavior.

To remain compatible with new convention, defer hotplug in a similar manner, but then generate events in 0-first order as we did in the past. Once func 0 present, fail any attempts to plug additional functions (as we do with PCIe).

For unplug, defer unplug operations in a similar manner, but generate unplug events such that function 0 is removed last in guest.

788d259 spapr_pci: fix multifunction hotplug
hw/ppc/spapr_pci.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 86 insertions(+), 7 deletions(-)

Upstream: git.qemu.org