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SubjectRe: [PATCH v9 17/18] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked
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On 15/10/2015 19:39, David Matlack wrote:
> But after spending more time reading the source code this morning I
> found that kvm_vcpu_check_block() eventually calls into
> vmx_sync_pir_to_irr(), which copies PIR to IRR and clears ON. And then
> apic_find_highest_irr() detects the pending posted interrupt.

Right. And related to this, Feng, can you check if this is still
necessary on kvm/queue:

@@ -6518,6 +6523,20 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_vcpu_reload_apic_access_page(vcpu);
}

+ /*
+ * KVM_REQ_EVENT is not set when posted interrupts are set by
+ * VT-d hardware, so we have to update RVI unconditionally.
+ */
+ if (kvm_lapic_enabled(vcpu)) {
+ /*
+ * Update architecture specific hints for APIC
+ * virtual interrupt delivery.
+ */
+ if (kvm_x86_ops->hwapic_irr_update)
+ kvm_x86_ops->hwapic_irr_update(vcpu,
+ kvm_lapic_find_highest_irr(vcpu));
+ }
+
if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
kvm_apic_accept_events(vcpu);
if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
@@ -6534,13 +6553,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_x86_ops->enable_irq_window(vcpu);

if (kvm_lapic_enabled(vcpu)) {
- /*
- * Update architecture specific hints for APIC
- * virtual interrupt delivery.
- */
- if (kvm_x86_ops->hwapic_irr_update)
- kvm_x86_ops->hwapic_irr_update(vcpu,
- kvm_lapic_find_highest_irr(vcpu));
update_cr8_intercept(vcpu);
kvm_lapic_sync_to_vapic(vcpu);
}

It may be obsolete now that we have the patch from Radim to set KVM_REQ_EVENT
in vmx_sync_pir_to_irr (http://permalink.gmane.org/gmane.linux.kernel/2057138).

Thanks,

Paolo


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