On 12/22/22 10:48, Michal Privoznik wrote:

When calling virConnectGetDomainCapabilities() (exposed as virsh domcapabilities) users have option to specify whatever sub-set of { emulatorbin, arch, machine, virttype } they want. Then we have a logic (hidden in virQEMUCapsCacheLookupDefault()) that picks qemuCaps that satisfy values passed by user. And whatever was not specified is then set to the default value as specified by picked qemuCaps. For instance: if no machine type was provided but emulatorbin was, then the machine type is set to the default one as defined by the emulatorbin.

Or, when just virttype was set then the remaining three values are set to their respective defaults. Except, we have a crasher in this case:

# virsh domcapabilities --virttype hvf error: Disconnected from qemu:///system due to end of file error: failed to get emulator capabilities error: End of file while reading data: Input/output error

This is because for 'hvf' virttype (at least my) QEMU does not have any machine type. Therefore, @machine is set to NULL and the rest of the code does not expect that.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_conf.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index ae5bbcd138..cbd339f594 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -1454,6 +1454,13 @@ virQEMUDriverGetDomainCapabilities(virQEMUDriver *driver, g_autoptr(virDomainCaps) domCaps = NULL; const char *path = virQEMUCapsGetBinary(qemuCaps);

+ if (!virQEMUCapsIsMachineSupported(qemuCaps, virttype, machine)) { + virReportError(VIR_ERR_INVALID_ARG, + _("the machine '%s' is not supported by emulator '%s'"), + NULLSTR(machine), path); + return NULL; + } + if (!(domCaps = virDomainCapsNew(path, machine, arch, virttype))) return NULL;

Self-NAK. We can do even better and validate the @arch and @virttype too. V2 coming shortly. Michal