Hi, We encountered a problem that when a domain starts, seabios failed to online a vCPU.
After investigation, we found that the reason is in kvm-kmod, KVM_APIC_INIT bit in vcpu->arch.apic->pending_events was overwritten by qemu, and thus an INIT IPI sent to AP was lost. Qemu does this since libvirtd sends a ‘query-cpus’ qmp command to qemu on VM start. In qemu, qmp_query_cpus-> cpu_synchronize_state-> kvm_cpu_synchronize_state-> do_kvm_cpu_synchronize_state, qemu gets registers/vcpu_events from kvm-kmod and sets cpu->kvm_vcpu_dirty to true, and vcpu thread in qemu will call kvm_arch_put_registers if cpu->kvm_vcpu_dirty is true, thus pending_events is overwritten by qemu. I think there is no need for qemu to set cpu->kvm_vcpu_dirty to true after ‘query-cpus’, and kvm-kmod should not clear KVM_APIC_INIT unconditionally. And I am not sure whether it is OK for qemu to set cpu->kvm_vcpu_dirty in do_kvm_cpu_synchronize_state in each caller. What’s your opinion?
