[PATCH] qemu: Do not silently allow non-available timers on non-x86 systems

[Boris Fiuczynski]

On 7/22/20 1:21 PM, Thomas Huth wrote:
> libvirt currently silently allows <timer name="kvmclock"/> and some
> other timer tags in the guest XML definition for timers that do not
> exist on non-x86 systems. We should not silently ignore these tags
> since the users might not get what they expected otherwise.
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1754887
> Signed-off-by: Thomas Huth <thuth at redhat.com>
> ---
>   src/qemu/qemu_validate.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index 488f258d00..667ac5cc23 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -371,6 +371,18 @@ qemuValidateDomainDefClockTimers(const virDomainDef *def,
>           case VIR_DOMAIN_TIMER_NAME_TSC:
>           case VIR_DOMAIN_TIMER_NAME_KVMCLOCK:
>           case VIR_DOMAIN_TIMER_NAME_HYPERVCLOCK:
> +            if (!ARCH_IS_X86(def->os.arch)) {
> +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                               _("Configuring the '%s' timer is not supported "
> +                                 "for virtType=%s arch=%s machine=%s guests"),
> +                               virDomainTimerNameTypeToString(timer->name),
> +                               virDomainVirtTypeToString(def->virtType),
> +                               virArchToString(def->os.arch),
> +                               def->os.machine);
> +                return -1;
> +            }
> +            break;
> +
>           case VIR_DOMAIN_TIMER_NAME_LAST:
>               break;
>   
> 

This would render previously as valid accepted domains invalid, e.g. on 
s390x using kvmclock: As long as the user does not specify the "present" 
attribute the domain starts without error since qemus cpu parameter is 
not extended.

The feedback of all other archs would be good to have.

@Daniel: What's your opinion?

-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294