Just like qemuDomainDefaultSCSIControllerModel() before that, split the function into an internal part and a trivial public wrapper. This allows us to rewrite the internal logic in the much more compact and readable if (condition) return value; if (other_condition) return other_value; return default_value; style, while still implementing the usual error handling behavior and avoiding any ambiguity caused by VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT having value -1. The conversion is straightforward if messy, with one notable exception: the piix3-uhci case, which serves as our fallback, has to be moved from the top of the function to the bottom due the change from the previous set-and-overwrite approach to the new return-early approach. The use of 'else if' is eliminated completely, comments are updated and improved. Signed-off-by: Andrea Bolognani <abologna@xxxxxxxxxx> --- src/qemu/qemu_domain.c | 143 +++++++++++++++++++++++++++++------------ 1 file changed, 101 insertions(+), 42 deletions(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 6801a883f4..db09af496b 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -4157,62 +4157,121 @@ qemuDomainDefaultSCSIControllerModel(virDomainControllerModelSCSI *model, } -static int -qemuDomainDefaultUSBControllerModel(virDomainControllerModelUSB *model, - bool autoAdded, - const virDomainDef *def, - virQEMUCaps *qemuCaps, - unsigned int parseFlags) +/* Internal. Use qemuDomainDefaultUSBControllerModel() instead */ +static virDomainControllerModelUSB +qemuDomainDefaultUSBControllerModelInternal(bool autoAdded, + const virDomainDef *def, + virQEMUCaps *qemuCaps, + unsigned int parseFlags) { - /* Default USB controller is piix3-uhci if available. */ - if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX3_USB_UHCI)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_PIIX3_UHCI; + bool abiUpdate = !!(parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE); if (ARCH_IS_S390(def->os.arch)) { /* No default model on s390x, one has to be provided * explicitly by the user */ - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NONE; - } else if (ARCH_IS_PPC64(def->os.arch)) { - /* To not break migration we need to set default USB controller - * for ppc64 to pci-ohci if we cannot change ABI of the VM. - * The nec-usb-xhci or qemu-xhci controller is used as default - * only for newly defined domains or devices. */ - if ((parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE) && - virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_QEMU_XHCI)) { - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; - } else if ((parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE) && - virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) { - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; - } else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI)) { - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_PCI_OHCI; - } else { - /* Explicitly fallback to legacy USB controller for PPC64. */ - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT; - } - } else if (def->os.arch == VIR_ARCH_AARCH64) { + return VIR_DOMAIN_CONTROLLER_MODEL_USB_NONE; + } + + if (ARCH_IS_PPC64(def->os.arch)) { + /* Newly-defined guests should use USB3 if possible */ + if (abiUpdate && virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_QEMU_XHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; + if (abiUpdate && virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; + + /* To preserve backwards compatibility, existing guests need to + * use pci-ohci (USB2) instead */ + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_PCI_OHCI; + + /* If neither USB3 nor USB2 can be used, bail */ + return VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT; + } + + if (def->os.arch == VIR_ARCH_AARCH64) { + /* Prefer USB3 */ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_QEMU_XHCI)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; - else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; + return VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; + + /* If USB3 is unavailable, we should probably bail by + * returning VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT here + * instead of possibly falling back to piix3-uhci (USB1), but + * historically we haven't done that and starting now might + * cause backwards compatibility issues */ } if (ARCH_IS_X86(def->os.arch)) { if (qemuDomainIsQ35(def) && autoAdded) { - /* Prefer adding a USB3 controller if supported, fall back - * to USB2 if there is no USB3 available, and if that's - * unavailable don't add anything. - */ + /* Prefer USB3 */ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_QEMU_XHCI)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; - else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; - else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ICH9_USB_EHCI1)) - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_EHCI1; - else - *model = VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT; + return VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI; + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI; + + /* Fall back to USB2 */ + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ICH9_USB_EHCI1)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_EHCI1; + + /* If no suitable device is available, simply avoid + * adding the controller. + * + * Note that this is only the case for the USB controller + * that gets automatically added for new guests, and only + * for the q35 machine type */ + return VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT; } } + /* The default USB controller is piix3-uhci (USB1) if available. + * This choice is a fairly poor one, rooted primarily in historical + * reasons; thankfully, in most cases we will overwrite it with a + * much more reasonable value below */ + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX3_USB_UHCI)) + return VIR_DOMAIN_CONTROLLER_MODEL_USB_PIIX3_UHCI; + + return VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT; +} + + +/** + * qemuDomainDefaultUSBControllerModel: + * @model: return location + * @autoAdded: whether this controller is being automatically added + * @def: domain definition + * @cont: controller definition, or NULL + * @qemuCaps: QEMU capabilities, or NULL + * @parseFlags: parse flags + * + * Choose a reasonable model to use for a USB controller where a + * specific one hasn't been provided by the user. + * + * The choice is based on a number of factors, including the guest's + * architecture and machine type. @qemuCaps, if provided, might be + * taken into consideration too. + * + * @autoAdded should be true is this is a controller that libvirt is + * trying to automatically add on domain creation for the user's + * convenience: in that case, the function might decide that the best + * course of action is to not add the controller after all. This + * decision will be communicated to the caller by setting @model + * to VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT. + * + * Not being able to come up with a value is NOT considered a + * failure. It's up to the caller to decide how to handle that + * scenario. + * + * Returns: 0 on success, <0 on failure. + */ +static int +qemuDomainDefaultUSBControllerModel(virDomainControllerModelUSB *model, + bool autoAdded, + const virDomainDef *def, + virQEMUCaps *qemuCaps, + unsigned int parseFlags) +{ + *model = qemuDomainDefaultUSBControllerModelInternal(autoAdded, def, qemuCaps, parseFlags); return 0; } -- 2.43.0 _______________________________________________ Devel mailing list -- devel@xxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxx