On Sat, 2023-01-28 at 01:09 +0000, Sean Christopherson wrote:
> On Tue, Nov 29, 2022, Maxim Levitsky wrote:
> > This patch adds two new vendor callbacks:
>
> No "this patch" please, just say what it does.
>
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 684a5519812fb2..46993ce61c92db 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -871,8 +871,13 @@ struct kvm_vcpu_arch {
> > u64 tsc_scaling_ratio; /* current scaling ratio */
> >
> > atomic_t nmi_queued; /* unprocessed asynchronous NMIs */
> > - unsigned nmi_pending; /* NMI queued after currently running handler */
> > +
> > + unsigned int nmi_pending; /*
> > + * NMI queued after currently running handler
> > + * (not including a hardware pending NMI (e.g vNMI))
> > + */
>
> Put the block comment above. I'd say collapse all of the comments about NMIs into
> a single big block comment.
>
> > bool nmi_injected; /* Trying to inject an NMI this entry */
> > +
> > bool smi_pending; /* SMI queued after currently running handler */
> > u8 handling_intr_from_guest;
> >
> > @@ -10015,13 +10022,34 @@ static void process_nmi(struct kvm_vcpu *vcpu)
> > * Otherwise, allow two (and we'll inject the first one immediately).
> > */
> > if (static_call(kvm_x86_get_nmi_mask)(vcpu) || vcpu->arch.nmi_injected)
> > - limit = 1;
> > + limit--;
> > +
> > + /* Also if there is already a NMI hardware queued to be injected,
> > + * decrease the limit again
> > + */
>
> /*
> * Block comment ...
> */
>
> > + if (static_call(kvm_x86_get_hw_nmi_pending)(vcpu))
>
> I'd prefer "is_hw_nmi_pending()" over "get", even if it means not pairing with
> "set". Though I think that's a good thing since they aren't perfect pairs.
>
> > + limit--;
> >
> > - vcpu->arch.nmi_pending += atomic_xchg(&vcpu->arch.nmi_queued, 0);
> > + if (limit <= 0)
> > + return;
> > +
> > + /* Attempt to use hardware NMI queueing */
> > + if (static_call(kvm_x86_set_hw_nmi_pending)(vcpu)) {
> > + limit--;
> > + nmi_to_queue--;
> > + }
> > +
> > + vcpu->arch.nmi_pending += nmi_to_queue;
> > vcpu->arch.nmi_pending = min(vcpu->arch.nmi_pending, limit);
> > kvm_make_request(KVM_REQ_EVENT, vcpu);
> > }
> >
> > +/* Return total number of NMIs pending injection to the VM */
> > +int kvm_get_total_nmi_pending(struct kvm_vcpu *vcpu)
> > +{
> > + return vcpu->arch.nmi_pending + static_call(kvm_x86_get_hw_nmi_pending)(vcpu);
>
> Nothing cares about the total count, this can just be;
I wanted to have the interface to be a bit more generic so that in theory you could have
more that one hardware NMI pending. I don't care much about it.
Best regards,
Maxim Levitsky
>
>
> bool kvm_is_nmi_pending(struct kvm_vcpu *vcpu)
> {
> return vcpu->arch.nmi_pending ||
> static_call(kvm_x86_is_hw_nmi_pending)(vcpu);
> }
>
>
> > +}
> > +
> > void kvm_make_scan_ioapic_request_mask(struct kvm *kvm,
> > unsigned long *vcpu_bitmap)
> > {
> > --
> > 2.26.3
> >
