Re: Add option to skip cpu feature and model verification in libvirt and rely on qemu 'enforce' option

On 23/11/22 5:44 pm, Daniel P. Berrangé wrote: > On Wed, Nov 23, 2022 at 12:51:39PM +0100, Jiri Denemark wrote: > > On Wed, Nov 23, 2022 at 11:41:03 +0000, Daniel P. Berrangé wrote: > > > Why can't it just use the exsting QEMU passthrough syntax we have. > > > I don't think we should be adding specifial support just for CPUs > > That would be nice, but the QEMU passthrough syntax cannot be used for > > changing options that libvirt already passes to QEMU. So using it would > > likely result in two separate -cpu options on QEMU command line. And it > > would not rule out the CPU verification code in libvirt. Remember, we > > add a default -cpu model in case there's none configured in the XML. > Two -cpu options isn't a problem, the latter will override the former, > which is fine from the level of support intended for QEMU passthrough > usage. > > For the libvirt checking, isn't the 'check=none' attr sufficient > to skip checks libvirt does. > > > With regards, > Daniel Actually even within check='none' libvirt does few checks e.g. virCPUValidateFeatures if feature string passed is proper and defined in libvirt. We could extend check='none' to remove even these kind of things. So Jiri suggested that making such kind of changes in general path is not good idea so discussion went to using separate cpu class <qemu:cpu>.