Re: Libvirt on little.BIG ARM systems unable to start guest if no cpuset is provided

On Tue, 14 Dec 2021 00:41:01 +0000, Qu Wenruo <quwenruo.btrfs(a)gmx.com&gt; wrote: > > > > On 2021/12/14 00:49, Marc Zyngier wrote: > > On Mon, 13 Dec 2021 16:06:14 +0000, > > Peter Maydell <peter.maydell(a)linaro.org&gt; wrote: > >> > >> KVM on big.little setups is a kernel-level question really; I've > >> cc'd the kvmarm list. > > > > Thanks Peter for throwing us under the big-little bus! ;-) > > > >> > >> On Mon, 13 Dec 2021 at 15:02, Qu Wenruo <quwenruo.btrfs(a)gmx.com&gt; wrote: > >>> > >>> > >>> > >>> On 2021/12/13 21:17, Michal Prívozník wrote: > >>>> On 12/11/21 02:58, Qu Wenruo wrote: > >>>>> Hi, > >>>>> > >>>>> Recently I got my libvirt setup on both RK3399 (RockPro64) and RPI CM4, > >>>>> with upstream kernels. > >>>>> > >>>>> For RPI CM4 its mostly smooth sail, but on RK3399 due to its little.BIG > >>>>> setup (core 0-3 are 4x A55 cores, and core 4-5 are 2x A72 cores), it > >>>>> brings quite some troubles for VMs. > >>>>> > >>>>> In short, without proper cpuset to bind the VM to either all A72 cores > >>>>> or all A55 cores, the VM will mostly fail to boot. > > > > s/A55/A53/. There were thankfully no A72+A55 ever produced (just the > > though of it makes me sick). > > > >>>>> > >>>>> Currently the working xml is: > >>>>> > >>>>> <vcpu placement='static' cpuset='4-5'>2</vcpu> > >>>>> <cpu mode='host-passthrough' check='none'/> > >>>>> > >>>>> But even with vcpupin, pinning each vcpu to each physical core, VM will > >>>>> mostly fail to start up due to vcpu initialization failed with -EINVAL. > > > > Disclaimer: I know nothing about libvirt (and no, I don't want to > > know! ;-). > > > > However, for things to be reliable, you need to taskset the whole QEMU > > process to the CPU type you intend to use. > > Yep, that's what I'm doing. Are you sure? The xml directive above seem to only apply to the vcpus, and no other QEMU thread.