KVM: PPC: Enable IRQFD support for the XICS interrupt controller

This makes it possible to use IRQFDs on platforms that use the XICS
interrupt controller.  To do this we implement kvm_irq_map_gsi() and
kvm_irq_map_chip_pin() in book3s_xics.c, so as to provide a 1-1 mapping
between global interrupt numbers and XICS interrupt source numbers.
For now, all interrupts are mapped as "IRQCHIP" interrupts, and no
MSI support is provided.

This means that kvm_set_irq can now get called with level == 0 or 1
as well as the powerpc-specific values KVM_INTERRUPT_SET,
KVM_INTERRUPT_UNSET and KVM_INTERRUPT_SET_LEVEL.  We change
ics_deliver_irq() to accept all those values, and remove its
report_status argument, as it is always false, given that we don't
support KVM_IRQ_LINE_STATUS.

This also adds support for interrupt ack notifiers to the XICS code
so that the IRQFD resampler functionality can be supported.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/powerpc/kvm/Kconfig

@@ -170,6 +170,8 @@ config KVM_MPIC
 config KVM_XICS
 	bool "KVM in-kernel XICS emulation"
 	depends on KVM_BOOK3S_64 && !KVM_MPIC
+	select HAVE_KVM_IRQCHIP
+	select HAVE_KVM_IRQFD
 	---help---
 	  Include support for the XICS (eXternal Interrupt Controller
 	  Specification) interrupt controller architecture used on

arch/powerpc/kvm/book3s_hv_rm_xics.c

@@ -401,6 +401,11 @@ int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
 		icp->rm_action |= XICS_RM_REJECT;
 		icp->rm_reject = irq;
 	}
+
+	if (!hlist_empty(&vcpu->kvm->irq_ack_notifier_list)) {
+		icp->rm_action |= XICS_RM_NOTIFY_EOI;
+		icp->rm_eoied_irq = irq;
+	}
  bail:
 	return check_too_hard(xics, icp);
 }

arch/powerpc/kvm/book3s_xics.c

@@ -64,8 +64,12 @@
 static void icp_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
 			    u32 new_irq);
 
-static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level,
-			   bool report_status)
+/*
+ * Return value ideally indicates how the interrupt was handled, but no
+ * callers look at it (given that we don't implement KVM_IRQ_LINE_STATUS),
+ * so just return 0.
+ */
+static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
 {
 	struct ics_irq_state *state;
 	struct kvmppc_ics *ics;
@@ -82,17 +86,14 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level,
 	if (!state->exists)
 		return -EINVAL;
 
-	if (report_status)
-		return state->asserted;
-
 	/*
 	 * We set state->asserted locklessly. This should be fine as
 	 * we are the only setter, thus concurrent access is undefined
 	 * to begin with.
 	 */
-	if (level == KVM_INTERRUPT_SET_LEVEL)
+	if (level == 1 || level == KVM_INTERRUPT_SET_LEVEL)
 		state->asserted = 1;
-	else if (level == KVM_INTERRUPT_UNSET) {
+	else if (level == 0 || level == KVM_INTERRUPT_UNSET) {
 		state->asserted = 0;
 		return 0;
 	}
@@ -100,7 +101,7 @@ static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level,
 	/* Attempt delivery */
 	icp_deliver_irq(xics, NULL, irq);
 
-	return state->asserted;
+	return 0;
 }
 
 static void ics_check_resend(struct kvmppc_xics *xics, struct kvmppc_ics *ics,
@@ -772,6 +773,8 @@ static noinline int kvmppc_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
 	if (state->asserted)
 		icp_deliver_irq(xics, icp, irq);
 
+	kvm_notify_acked_irq(vcpu->kvm, 0, irq);
+
 	return H_SUCCESS;
 }
 
@@ -789,6 +792,8 @@ static noinline int kvmppc_xics_rm_complete(struct kvm_vcpu *vcpu, u32 hcall)
 		icp_check_resend(xics, icp);
 	if (icp->rm_action & XICS_RM_REJECT)
 		icp_deliver_irq(xics, icp, icp->rm_reject);
+	if (icp->rm_action & XICS_RM_NOTIFY_EOI)
+		kvm_notify_acked_irq(vcpu->kvm, 0, icp->rm_eoied_irq);
 
 	icp->rm_action = 0;
 
@@ -1170,7 +1175,16 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
 {
 	struct kvmppc_xics *xics = kvm->arch.xics;
 
-	return ics_deliver_irq(xics, irq, level, line_status);
+	return ics_deliver_irq(xics, irq, level);
+}
+
+int kvm_set_msi(struct kvm_kernel_irq_routing_entry *irq_entry, struct kvm *kvm,
+		int irq_source_id, int level, bool line_status)
+{
+	if (!level)
+		return -1;
+	return kvm_set_irq(kvm, irq_source_id, irq_entry->gsi,
+			   level, line_status);
 }
 
 static int xics_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
@@ -1301,3 +1315,26 @@ void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu)
 	vcpu->arch.icp = NULL;
 	vcpu->arch.irq_type = KVMPPC_IRQ_DEFAULT;
 }
+
+static int xics_set_irq(struct kvm_kernel_irq_routing_entry *e,
+			struct kvm *kvm, int irq_source_id, int level,
+			bool line_status)
+{
+	return kvm_set_irq(kvm, irq_source_id, e->gsi, level, line_status);
+}
+
+int kvm_irq_map_gsi(struct kvm *kvm,
+		    struct kvm_kernel_irq_routing_entry *entries, int gsi)
+{
+	entries->gsi = gsi;
+	entries->type = KVM_IRQ_ROUTING_IRQCHIP;
+	entries->set = xics_set_irq;
+	entries->irqchip.irqchip = 0;
+	entries->irqchip.pin = gsi;
+	return 1;
+}
+
+int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned irqchip, unsigned pin)
+{
+	return pin;
+}

arch/powerpc/kvm/book3s_xics.h

@@ -71,9 +71,11 @@ struct kvmppc_icp {
 #define XICS_RM_KICK_VCPU	0x1
 #define XICS_RM_CHECK_RESEND	0x2
 #define XICS_RM_REJECT		0x4
+#define XICS_RM_NOTIFY_EOI	0x8
 	u32 rm_action;
 	struct kvm_vcpu *rm_kick_target;
 	u32  rm_reject;
+	u32  rm_eoied_irq;
 
 	/* Debug stuff for real mode */
 	union kvmppc_icp_state rm_dbgstate;