Re: [PATCH v2 3/8] KVM: x86: Refactor kvm_hv_flush_tlb() to reduce indentation

Sean Christopherson
2021-12-03T23:45:39Z

On Mon, Nov 01, 2021, Vitaly Kuznetsov wrote:
> Sean Christopherson <seanjc@google.com> writes:
>
> > Refactor the "extended" path of kvm_hv_flush_tlb() to reduce the nesting
> > depth for the non-fast sparse path, and to make the code more similar to
> > the extended path in kvm_hv_send_ipi().
> >
> > No functional change intended.
> >
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> > arch/x86/kvm/hyperv.c | 40 +++++++++++++++++++++-------------------
> > 1 file changed, 21 insertions(+), 19 deletions(-)
> >
> > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> > index cf18aa1712bf..e68931ed27f6 100644
> > --- a/arch/x86/kvm/hyperv.c
> > +++ b/arch/x86/kvm/hyperv.c
> > @@ -1814,31 +1814,33 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
> > if (hc->var_cnt != bitmap_weight((unsigned long *)&valid_bank_mask, 64))
> > return HV_STATUS_INVALID_HYPERCALL_INPUT;
> >
> > - if (!hc->var_cnt && !all_cpus)
> > + if (all_cpus)
> > + goto do_flush;
>
> You could've probably done:
>
> if (all_cpus) {
> kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH_GUEST);
> goto ret_success;
> }
>
> to get rid on the second 'all_cpus' check (and maybe even 'do_flush'
> label with some extra work) below.

Yeah, but the !ex path also uses all_cpus, and in general I'd prefer to keep the
two flush requests bundled together.