Roman Kagan <rkagan@xxxxxxxxxxxxx> writes: > On Fri, Jun 29, 2018 at 04:14:53PM +0200, Vitaly Kuznetsov wrote: >> VP_INDEX almost always matches VCPU id and get_vcpu_by_vpidx() is fast, >> use it instead of traversing full vCPU list every time. >> >> To support the change switch kvm_make_vcpus_request_mask() to checking >> vcpu_id instead of vcpu index, > > I'm afraid you can't do this: vcpu_id (== apic id) can be sparse, i.e. > it's not very well suited for bitmaps and can exceed the max number of > vcpus. True. The bitmap should be of KVM_MAX_VCPU_ID size, not KVM_MAX_VCPUS. Unfortunately there's no convenient way to get VCPU idx from VCPU id, kvm_vcpu_get_idx() just walks the whole list :-( I see two possible options: 1) Add vcpu_idx fields to struct kvm_vcpu 2) Keep the change expecting masks of KVM_MAX_VCPU_ID in kvm_make_vcpus_request_mask(). KVM_MAX_VCPU_ID is currently 1023 so our bitmaps will be 16 longs long. Not sure if it's too much. -- Vitaly
