Re: [PATCH v2 08/17] KVM: TDX: Complete interrupts after TD exit

[Chao Gao <chao.gao@intel.com>]

>+static void tdx_complete_interrupts(struct kvm_vcpu *vcpu)
>+{
>+	/* Avoid costly SEAMCALL if no NMI was injected. */
>+	if (vcpu->arch.nmi_injected) {
>+		/*
>+		 * No need to request KVM_REQ_EVENT because PEND_NMI is still
>+		 * set if NMI re-injection needed.  No other event types need
>+		 * to be handled because TDX doesn't support injection of
>+		 * exception, SMI or interrupt (via event injection).
>+		 */
>+		vcpu->arch.nmi_injected = td_management_read8(to_tdx(vcpu),
>+							      TD_VCPU_PEND_NMI);
>+	}

Why does KVM care whether/when an NMI is injected by the TDX module?

I think we can simply set nmi_injected to false unconditionally here, or even in
tdx_inject_nmi(). From KVM's perspective, NMI injection is complete right after
writing to PEND_NMI. It is the TDX module that should inject the NMI at the
right time and do the re-injection.


>+}
>+