linux-kernel - [RFC PATCH v5 075/104] KVM: x86: Check for pending APICv interrupt in kvm_vcpu_has

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Date:   Fri,  4 Mar 2022 11:49:31 -0800
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [RFC PATCH v5 075/104] KVM: x86: Check for pending APICv interrupt in kvm_vcpu_has_events()

From: Sean Christopherson <sean.j.christopherson@...el.com>

Return true for kvm_vcpu_has_events() if the vCPU has a pending APICv
interrupt to support TDX's usage of APICv.  Unlike VMX, TDX doesn't have
access to vmcs.GUEST_INTR_STATUS and so can't emulate posted interrupts,
i.e. needs to generate a posted interrupt and more importantly can't
manually move requested interrupts into the vIRR (which it also doesn't
have access to).

Because pi_has_pending_interrupt() is heavy operation which uses two atomic
test bit operations and one atomic 256 bit bitmap check, introduce new
callback for this check instead of reusing dy_apicv_has_pending_interrupt()
callback to avoid affecting the exiting code.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/vmx/main.c         | 9 +++++++++
 arch/x86/kvm/x86.c              | 5 ++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 489374a57b66..8dab9f16f559 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1491,6 +1491,7 @@ struct kvm_x86_ops {
 	void (*start_assignment)(struct kvm *kvm);
 	void (*apicv_post_state_restore)(struct kvm_vcpu *vcpu);
 	bool (*dy_apicv_has_pending_interrupt)(struct kvm_vcpu *vcpu);
+	bool (*apicv_has_pending_interrupt)(struct kvm_vcpu *vcpu);
 
 	int (*set_hv_timer)(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
 			    bool *expired);
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 882358ac270b..d75caf0d6861 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -148,6 +148,14 @@ static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	return vmx_vcpu_load(vcpu, cpu);
 }
 
+static bool vt_apicv_has_pending_interrupt(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu))
+		return pi_has_pending_interrupt(vcpu);
+
+	return false;
+}
+
 static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
 {
 	if (is_td_vcpu(vcpu))
@@ -297,6 +305,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.sync_pir_to_irr = vmx_sync_pir_to_irr,
 	.deliver_interrupt = vmx_deliver_interrupt,
 	.dy_apicv_has_pending_interrupt = pi_has_pending_interrupt,
+	.apicv_has_pending_interrupt = vt_apicv_has_pending_interrupt,
 
 	.set_tss_addr = vmx_set_tss_addr,
 	.set_identity_map_addr = vmx_set_identity_map_addr,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 89d04cd64cd0..314ae43e07bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12111,7 +12111,10 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
 
 	if (kvm_arch_interrupt_allowed(vcpu) &&
 	    (kvm_cpu_has_interrupt(vcpu) ||
-	    kvm_guest_apic_has_interrupt(vcpu)))
+	     kvm_guest_apic_has_interrupt(vcpu) ||
+	     (vcpu->arch.apicv_active &&
+	      kvm_x86_ops.apicv_has_pending_interrupt &&
+	      kvm_x86_ops.apicv_has_pending_interrupt(vcpu))))
 		return true;
 
 	if (kvm_hv_has_stimer_pending(vcpu))
-- 
2.25.1