[PATCH v2 07/20] KVM: x86/xen: Extract delivery of event to vCPU into a separate helper

[Sean Christopherson <seanjc@google.com>]

Hoist the actual fastpath delivery of an event to a vCPU into a separate
helper so that CLASS()-based gpc locking+checking can be used without
needing to implement scoped versions.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/xen.c | 100 ++++++++++++++++++++++++---------------------
 1 file changed, 54 insertions(+), 46 deletions(-)

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 0c6b74b97408..020ef0ddab01 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -1775,6 +1775,57 @@ static void kvm_xen_check_poller(struct kvm_vcpu *vcpu, int port)
 	}
 }
 
+static void __kvm_xen_set_evtchn_fast(struct kvm_vcpu *vcpu, int port_word_bit)
+{
+	struct gfn_to_pfn_cache *gpc = &vcpu->arch.xen.vcpu_info_cache;
+	bool kick_vcpu = false;
+
+	/* Now switch to the vCPU's vcpu_info to set the index and pending_sel */
+	if (!read_trylock(&gpc->lock)) {
+		/*
+		 * Could not access the vcpu_info. Set the bit in-kernel and
+		 * prod the vCPU to deliver it for itself.
+		 */
+		if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel))
+			kick_vcpu = true;
+		goto out_kick;
+	}
+	if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
+		if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel))
+			kick_vcpu = true;
+		goto out_unlock;
+	}
+
+	if (IS_ENABLED(CONFIG_64BIT) && vcpu->kvm->arch.xen.long_mode) {
+		struct vcpu_info *vcpu_info = gpc->khva;
+		if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) {
+			WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
+			kick_vcpu = true;
+		}
+	} else {
+		struct compat_vcpu_info *vcpu_info = gpc->khva;
+		if (!test_and_set_bit(port_word_bit,
+					(unsigned long *)&vcpu_info->evtchn_pending_sel)) {
+			WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
+			kick_vcpu = true;
+		}
+	}
+
+	/* For the per-vCPU lapic vector, deliver it as MSI. */
+	if (kick_vcpu && vcpu->arch.xen.upcall_vector) {
+		kvm_xen_inject_vcpu_vector(vcpu);
+		kick_vcpu = false;
+	}
+
+out_unlock:
+	read_unlock(&gpc->lock);
+out_kick:
+	if (kick_vcpu) {
+		kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+}
+
 /*
  * The return value from this function is propagated to kvm_set_irq() API,
  * so it returns:
@@ -1791,7 +1842,6 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
 	struct kvm_vcpu *vcpu;
 	unsigned long *pending_bits, *mask_bits;
 	int port_word_bit;
-	bool kick_vcpu = false;
 	int vcpu_idx, rc;
 
 	vcpu_idx = READ_ONCE(xe->vcpu_idx);
@@ -1843,55 +1893,13 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
 		kvm_xen_check_poller(vcpu, xe->port);
 	} else {
 		rc = 1; /* Delivered to the bitmap in shared_info. */
-		/* Now switch to the vCPU's vcpu_info to set the index and pending_sel */
-		read_unlock(&gpc->lock);
-		gpc = &vcpu->arch.xen.vcpu_info_cache;
-
-		if (!read_trylock(&gpc->lock)) {
-			/*
-			 * Could not access the vcpu_info. Set the bit in-kernel
-			 * and prod the vCPU to deliver it for itself.
-			 */
-			if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel))
-				kick_vcpu = true;
-			goto out_kick;
-		}
-		if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
-			if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel))
-				kick_vcpu = true;
-			goto out_unlock;
-		}
-
-		if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
-			struct vcpu_info *vcpu_info = gpc->khva;
-			if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) {
-				WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
-				kick_vcpu = true;
-			}
-		} else {
-			struct compat_vcpu_info *vcpu_info = gpc->khva;
-			if (!test_and_set_bit(port_word_bit,
-					      (unsigned long *)&vcpu_info->evtchn_pending_sel)) {
-				WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
-				kick_vcpu = true;
-			}
-		}
-
-		/* For the per-vCPU lapic vector, deliver it as MSI. */
-		if (kick_vcpu && vcpu->arch.xen.upcall_vector) {
-			kvm_xen_inject_vcpu_vector(vcpu);
-			kick_vcpu = false;
-		}
 	}
 
- out_unlock:
+out_unlock:
 	read_unlock(&gpc->lock);
- out_kick:
-	if (kick_vcpu) {
-		kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
-		kvm_vcpu_kick(vcpu);
-	}
 
+	if (rc == 1)
+		__kvm_xen_set_evtchn_fast(vcpu, port_word_bit);
 	return rc;
 }
 
-- 
2.54.0.823.g6e5bcc1fc9-goog