On Fri, May 20, 2022 at 02:39:28PM +0800, Zeng Guang wrote: >Specify maximum possible APIC ID assigned for current VM session prior to >the creation of vCPUs. KVM need set up VM-scoped data structure indexed by >the APIC ID, e.g. Posted-Interrupt Descriptor table to support Intel IPI >virtualization. > >It can be achieved by calling KVM_ENABLE_CAP for KVM_CAP_MAX_VCPU_ID >capability once KVM has already enabled it. Otherwise, simply prompts >that KVM doesn't support this capability yet. > >Signed-off-by: Zeng Guang <guang.zeng@xxxxxxxxx> >--- > hw/i386/x86.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > >diff --git a/hw/i386/x86.c b/hw/i386/x86.c >index 4cf107baea..ff74492325 100644 >--- a/hw/i386/x86.c >+++ b/hw/i386/x86.c >@@ -106,7 +106,7 @@ out: > > void x86_cpus_init(X86MachineState *x86ms, int default_cpu_version) > { >- int i; >+ int i, ret; > const CPUArchIdList *possible_cpus; > MachineState *ms = MACHINE(x86ms); > MachineClass *mc = MACHINE_GET_CLASS(x86ms); >@@ -123,6 +123,13 @@ void x86_cpus_init(X86MachineState *x86ms, int default_cpu_version) > */ > x86ms->apic_id_limit = x86_cpu_apic_id_from_index(x86ms, > ms->smp.max_cpus - 1) + 1; >+ >+ ret = kvm_vm_enable_cap(kvm_state, KVM_CAP_MAX_VCPU_ID, >+ 0, x86ms->apic_id_limit); >+ if (ret < 0) { >+ error_report("kvm: Set max vcpu id not supported: %s", strerror(-ret)); >+ } This piece of code is specific to KVM. Please move it to kvm-all.c and invoke a wrapper function here. As kvm accelerator isn't necessarily enabled, the function call should be guarded by kvm_enabled(). And I think the error message can be omitted because the failure doesn't impact functionality; just a few more pages will be allocated by KVM.