Re: [REGRESSION][BISECTED] from bd9bbc96e835: cannot boot Win11 KVM guest

[Juri Lelli <juri.lelli@redhat.com>]

On 16/12/24 20:40, Ranguvar wrote:
> On Monday, December 16th, 2024 at 16:50, Sean Christopherson <seanjc@google.com> wrote:
> > 
> > On Mon, Dec 16, 2024, Juri Lelli wrote:
> > 
> > > On 14/12/24 19:52, Peter Zijlstra wrote:
> > > 
> > > > On Sat, Dec 14, 2024 at 06:32:57AM +0000, Ranguvar wrote:
> > > > 
> > > > > I have in kernel cmdline `iommu=pt isolcpus=1-7,17-23 rcu_nocbs=1-7,17-23 nohz_full=1-7,17-23`. Removing iommu=pt does not produce a change, and
> > > > > dropping the core isolation freezes the host on VM startup.
> > 
> > As in, dropping all of isolcpus, rcu_nocbs, and nohz_full? Or just dropping
> > isolcpus?
> 
> Thanks for looking.
> I had dropped all three, but not altered the VM guest config, which is:
> 
> <cputune>
> <vcpupin vcpu='0' cpuset='2'/>
> <vcpupin vcpu='1' cpuset='18'/>
> ...
> <vcpupin vcpu='11' cpuset='23'/>
> <emulatorpin cpuset='1,17'/>
> <iothreadpin iothread='1' cpuset='1,17'/>
> <vcpusched vcpus='0' scheduler='fifo' priority='95'/>
> ...
> <iothreadsched iothreads='1' scheduler='fifo' priority='50'/>

Are you disabling/enabling/configuring RT throttling (sched_rt_{runtime,
period}_us) in your configuration?

> </cputune>
> 
> CPU mode is host-passthrough, cache mode is passthrough.
> 
> The 24GB VRAM did cause trouble when setting up resizeable BAR months ago as well. It necessitated a special qemu config:
> <qemu:commandline>
> <qemu:arg value='-fw_cfg'/>
> <qemu:arg value='opt/ovmf/PciMmio64Mb,string=65536'/>
> </qemu:commandline>
>