linux-kernel - [RFC PATCH v5 076/104] KVM: x86: Add option to force LAPIC expiration wait

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Date:   Fri,  4 Mar 2022 11:49:32 -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 076/104] KVM: x86: Add option to force LAPIC expiration wait

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

Add an option to skip the IRR check-in kvm_wait_lapic_expire().  This
will be used by TDX to wait if there is an outstanding notification for
a TD, i.e. a virtual interrupt is being triggered via posted interrupt
processing.  KVM TDX doesn't emulate PI processing, i.e. there will
never be a bit set in IRR/ISR, so the default behavior for APICv of
querying the IRR doesn't work as intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/lapic.c   | 4 ++--
 arch/x86/kvm/lapic.h   | 2 +-
 arch/x86/kvm/svm/svm.c | 2 +-
 arch/x86/kvm/vmx/vmx.c | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 9322e6340a74..d49f029ef0e3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1620,12 +1620,12 @@ static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
 		__wait_lapic_expire(vcpu, tsc_deadline - guest_tsc);
 }
 
-void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
+void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu, bool force_wait)
 {
 	if (lapic_in_kernel(vcpu) &&
 	    vcpu->arch.apic->lapic_timer.expired_tscdeadline &&
 	    vcpu->arch.apic->lapic_timer.timer_advance_ns &&
-	    lapic_timer_int_injected(vcpu))
+	    (force_wait || lapic_timer_int_injected(vcpu)))
 		__kvm_wait_lapic_expire(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_wait_lapic_expire);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 2b44e533fc8d..2a0119ef9e96 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -233,7 +233,7 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)
 
 bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
 
-void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu);
+void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu, bool force_wait);
 
 void kvm_bitmap_or_dest_vcpus(struct kvm *kvm, struct kvm_lapic_irq *irq,
 			      unsigned long *vcpu_bitmap);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c7eec23e9ebe..a46415845f48 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3766,7 +3766,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 	clgi();
 	kvm_load_guest_xsave_state(vcpu);
 
-	kvm_wait_lapic_expire(vcpu);
+	kvm_wait_lapic_expire(vcpu, false);
 
 	/*
 	 * If this vCPU has touched SPEC_CTRL, restore the guest's value if
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 00f88aa25047..9b7bd52d19a9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6838,7 +6838,7 @@ fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	if (enable_preemption_timer)
 		vmx_update_hv_timer(vcpu);
 
-	kvm_wait_lapic_expire(vcpu);
+	kvm_wait_lapic_expire(vcpu, false);
 
 	/*
 	 * If this vCPU has touched SPEC_CTRL, restore the guest's value if
-- 
2.25.1