[libvirt] [PATCH] qemu: Use legacy USB on ppc64

Commit 8156493d8db9 changed libvirt so that '-device pci-ohci' would be used instead of '-usb' on ppc64 when no specific USB controller model had been specified in the guest configuration. While the device that ends up being presented by the guest is exactly the same, '-usb' causes it to be assigned to PCI address 00:00.0 while '-device pci-ohci', being subject to the regular PCI address assignment logic, will be at a different address. This PCI address mismatch breaks migration of existing guests to new libvirt versions. Luckily, when QEMU has switched its default '-usb' controller from pci-ohci to nec-usb-xhci (QEMU commit 57040d451315), it has done so without affecting older machine types, which means we can keep using '-usb' without risking guest ABI breakage. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1357468 --- src/qemu/qemu_command.c | 8 +++++--- tests/qemuxml2argvdata/qemuxml2argv-ppc64-usb-controller.args | 2 +- tests/qemuxml2argvdata/qemuxml2argv-pseries-usb-default.args | 2 +- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 2e04f57..9050e77 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -2827,9 +2827,11 @@ qemuBuildControllerDevCommandLine(virCommandPtr cmd, /* We're not using legacy usb controller for q35 */ if (ARCH_IS_PPC64(def->os.arch)) { - /* For ppc64 the legacy was OHCI */ - if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI)) - need_legacy = true; + /* ppc64 needs to use the -usb flag in order not to break + * migration of existing guests: the legacy USB controller + * uses a PCI address that we have no way of assigning + * using the usual -device machinery */ + need_legacy = true; } else { /* For anything else, we used PIIX3_USB_UHCI */ if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX3_USB_UHCI)) diff --git a/tests/qemuxml2argvdata/qemuxml2argv-ppc64-usb-controller.args b/tests/qemuxml2argvdata/qemuxml2argv-ppc64-usb-controller.args index 2ec2231..bed5045 100644 --- a/tests/qemuxml2argvdata/qemuxml2argv-ppc64-usb-controller.args +++ b/tests/qemuxml2argvdata/qemuxml2argv-ppc64-usb-controller.args @@ -15,5 +15,5 @@ QEMU_AUDIO_DRV=none \ -nodefaults \ -monitor unix:/tmp/lib/domain--1-QEMUGuest1/monitor.sock,server,nowait \ -boot c \ --device pci-ohci,id=usb,bus=pci,addr=0x1 \ +-usb \ -device virtio-balloon-pci,id=balloon0,bus=pci,addr=0x6 diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pseries-usb-default.args b/tests/qemuxml2argvdata/qemuxml2argv-pseries-usb-default.args index 251e786..2839dea 100644 --- a/tests/qemuxml2argvdata/qemuxml2argv-pseries-usb-default.args +++ b/tests/qemuxml2argvdata/qemuxml2argv-pseries-usb-default.args @@ -19,6 +19,6 @@ server,nowait \ -mon chardev=charmonitor,id=monitor,mode=readline \ -no-acpi \ -boot c \ --device pci-ohci,id=usb,bus=pci,addr=0x1 \ +-usb \ -chardev pty,id=charserial0 \ -device spapr-vty,chardev=charserial0,reg=0x30000000 -- 2.7.4