On Thu, Sep 17, 2020 at 10:56:18AM +0200, Paolo Bonzini wrote: > On 17/09/20 04:25, yadong.qi@xxxxxxxxx wrote: > > From: Yadong Qi <yadong.qi@xxxxxxxxx> > > > > Background: We have a lightweight HV, it needs INIT-VMExit and > > SIPI-VMExit to wake-up APs for guests since it do not monitoring > > the Local APIC. But currently virtual wait-for-SIPI(WFS) state > > is not supported in KVM, so when running on top of KVM, the L1 > > HV cannot receive the INIT-VMExit and SIPI-VMExit which cause > > the L2 guest cannot wake up the APs. > > > > This patch is incomplete, it emulated wait-for-SIPI state by halt > > the vCPU and emulated SIPI-VMExit to L1 when trapped SIPI signal > > from L2. I am posting it RFC to gauge whether or not upstream > > KVM is interested in emulating wait-for-SIPI state before > > investing the time to finish the full support. > > Yes, the patch makes sense and is a good addition. What exactly is > missing? (Apart from test cases in kvm-unit-tests!) nested_vmx_run() puts the vCPU into KVM_MP_STATE_HALTED instead of properly transitioning to INIT_RECEIVED, e.g. events that arrive while the vCPU is supposed to be in WFS will be incorrectly recognized. I suspect there are other gotchas lurking, but that's the big one.
