Re: [libvirt] [PATCH v2 01/42] conf: add enum constants for default controller models

On Thu, Feb 15, 2018 at 04:43:06PM +0000, Daniel P. Berrangé wrote: > The controller model is slightly unusual in that the default value is > -1, not 0. As a result the default value is not covered by any of the > existing enum cases. This in turn means that any switch() statements > that think they have covered all cases, will in fact not match the > default value at all. In the qemuDomainDeviceCalculatePCIConnectFlags() > method this has caused a serious mistake where we fallthough from the s/fallthough/fallthrough/ > SCSI controller case, to the VirtioSerial controller case, and from > the USB controller case to the IDE controller case. > > By adding explicit enum constant starting at -1, we can ensure switches > remember to handle the default case. > > Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; > --- > src/conf/domain_addr.c | 5 +++++ > src/conf/domain_conf.c | 1 + > src/conf/domain_conf.h | 4 ++++ > src/qemu/qemu_command.c | 17 ++++++++++++++--- > src/qemu/qemu_domain.c | 10 +++++++++- > src/qemu/qemu_domain_address.c | 22 ++++++++++++++++++++++ > src/vbox/vbox_common.c | 13 +++++++++---- > 7 files changed, 64 insertions(+), 8 deletions(-) > > diff --git a/src/conf/domain_addr.c b/src/conf/domain_addr.c > index 6422682391..df19c6be1a 100644 > --- a/src/conf/domain_addr.c > +++ b/src/conf/domain_addr.c > @@ -39,6 +39,7 @@ virDomainPCIControllerModelToConnectType(virDomainControllerModelPCI model) > * the equivalent VIR_PCI_CONNECT_TYPE_*. > */ > switch (model) { > + case VIR_DOMAIN_CONTROLLER_MODEL_PCI_DEFAULT: > case VIR_DOMAIN_CONTROLLER_MODEL_PCI_LAST: > case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT: > case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT: > @@ -344,6 +345,9 @@ virDomainPCIAddressBusSetModel(virDomainPCIAddressBusPtr bus, > bus->maxSlot = VIR_PCI_ADDRESS_SLOT_LAST; > break; > > + case VIR_DOMAIN_CONTROLLER_MODEL_PCI_DEFAULT: > + break; > + Unlike '-usb' for USB controllers, there is no -pci for pci controllers - we need to know the model at the time of building the command line. Not having one set here is either an error in the user input or the part of our code that should have filled the model in. If we want to be robust, this should be grouped with the next case.

> case VIR_DOMAIN_CONTROLLER_MODEL_PCI_LAST: > virReportError(VIR_ERR_INTERNAL_ERROR, > "%s", _("PCI controller model was not set correctly")); > @@ -1746,6 +1750,7 @@ virDomainUSBAddressControllerModelToPorts(virDomainControllerDefPtr cont) > return cont->opts.usbopts.ports; > return 8; > > + case VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT: > case VIR_DOMAIN_CONTROLLER_MODEL_USB_NONE: > case VIR_DOMAIN_CONTROLLER_MODEL_USB_LAST: > break; > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 6c73cd7bfe..2a75a169c2 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c > index 178ec24ae7..e114f5dfcf 100644 > --- a/src/qemu/qemu_domain.c > +++ b/src/qemu/qemu_domain.c > @@ -4098,11 +4098,16 @@ qemuDomainCheckSCSIControllerModel(virQEMUCapsPtr qemuCaps, > case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_AUTO: > case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_BUSLOGIC: > case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VMPVSCSI: > - case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LAST: > virReportError(VIR_ERR_CONFIG_UNSUPPORTED, > _("Unsupported controller model: %s"), > virDomainControllerModelSCSITypeToString(model)); > return false; > + case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_DEFAULT: > + case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LAST: > + virReportError(VIR_ERR_INTERNAL_ERROR, > + _("Unexpected SCSI controller model %d"), > + model); > + return false; > } > > return true; [...] > diff --git a/src/qemu/qemu_domain_address.c b/src/qemu/qemu_domain_address.c > index e28119e4b1..de565dbf74 100644 > --- a/src/qemu/qemu_domain_address.c > +++ b/src/qemu/qemu_domain_address.c > @@ -513,6 +513,16 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev, > > case VIR_DOMAIN_CONTROLLER_TYPE_USB: > switch ((virDomainControllerModelUSB) cont->model) { > + case VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT: > + /* XXX it isn't clear that this is the right > + * thing to do here. We probably ought to > + * return 0, but that breaks test suite right > + * now because we call this method before we > + * have turned the _DEFAULT case into a > + * specific choice > + */ qemuDomainControllerDefPostParse should have filled this one in for most QEMU machine/capabilities combinations. If it's still at default at this point, we're going to use "-usb", which should be a PCI device.

> + return pciFlags; > + > case VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI: > case VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI: > return pcieFlags; > @@ -540,6 +550,16 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev, > > case VIR_DOMAIN_CONTROLLER_TYPE_SCSI: > switch ((virDomainControllerModelSCSI) cont->model) { > + case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_DEFAULT: > + /* XXX it isn't clear that this is the right > + * thing to do here. We probably ought to > + * return 0, but that breaks test suite right > + * now because we call this method before we > + * have turned the _DEFAULT case into a > + * specific choice > + */ > + return pciFlags; > + Slightly different: a default SCSI controller cannot be formatted unless we turn it into a model. qemuDomainSetSCSIControllerModel in qemuDomainControllerDefPostParse errors out if we have no QEMU capabilities, (which probably should be relaxed as it might break loading of existing domains if the QEMU binary is not present). But the test suite passes even with return 0, so the comment is misleading.