linux-kernel - [PATCH 02/18] KVM: x86: Add kvm_icr_to_lapic_irq() helper to allow for fastpath IPIs

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Message-ID: <20250805190526.1453366-3-seanjc@google.com>
Date: Tue,  5 Aug 2025 12:05:10 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Xin Li <xin@...or.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Sandipan Das <sandipan.das@....com>
Subject: [PATCH 02/18] KVM: x86: Add kvm_icr_to_lapic_irq() helper to allow
 for fastpath IPIs

Extract the code for converting an ICR message into a kvm_lapic_irq
structure into a local helper so that a fast-only IPI path can share the
conversion logic.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/lapic.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8172c2042dd6..9f9846980625 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1481,24 +1481,30 @@ void kvm_apic_set_eoi_accelerated(struct kvm_vcpu *vcpu, int vector)
 }
 EXPORT_SYMBOL_GPL(kvm_apic_set_eoi_accelerated);
 
-void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high)
+static void kvm_icr_to_lapic_irq(struct kvm_lapic *apic, u32 icr_low,
+				 u32 icr_high, struct kvm_lapic_irq *irq)
 {
-	struct kvm_lapic_irq irq;
-
 	/* KVM has no delay and should always clear the BUSY/PENDING flag. */
 	WARN_ON_ONCE(icr_low & APIC_ICR_BUSY);
 
-	irq.vector = icr_low & APIC_VECTOR_MASK;
-	irq.delivery_mode = icr_low & APIC_MODE_MASK;
-	irq.dest_mode = icr_low & APIC_DEST_MASK;
-	irq.level = (icr_low & APIC_INT_ASSERT) != 0;
-	irq.trig_mode = icr_low & APIC_INT_LEVELTRIG;
-	irq.shorthand = icr_low & APIC_SHORT_MASK;
-	irq.msi_redir_hint = false;
+	irq->vector = icr_low & APIC_VECTOR_MASK;
+	irq->delivery_mode = icr_low & APIC_MODE_MASK;
+	irq->dest_mode = icr_low & APIC_DEST_MASK;
+	irq->level = (icr_low & APIC_INT_ASSERT) != 0;
+	irq->trig_mode = icr_low & APIC_INT_LEVELTRIG;
+	irq->shorthand = icr_low & APIC_SHORT_MASK;
+	irq->msi_redir_hint = false;
 	if (apic_x2apic_mode(apic))
-		irq.dest_id = icr_high;
+		irq->dest_id = icr_high;
 	else
-		irq.dest_id = GET_XAPIC_DEST_FIELD(icr_high);
+		irq->dest_id = GET_XAPIC_DEST_FIELD(icr_high);
+}
+
+void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high)
+{
+	struct kvm_lapic_irq irq;
+
+	kvm_icr_to_lapic_irq(apic, icr_low, icr_high, &irq);
 
 	trace_kvm_apic_ipi(icr_low, irq.dest_id);
 
-- 
2.50.1.565.gc32cd1483b-goog