KVM: arm/arm64: Enable irqchip routing

This patch adds compilation and link against irqchip.

Main motivation behind using irqchip code is to enable MSI
routing code. In the future irqchip routing may also be useful
when targeting multiple irqchips.

Routing standard callbacks now are implemented in vgic-irqfd:
- kvm_set_routing_entry
- kvm_set_irq
- kvm_set_msi

They only are supported with new_vgic code.

Both HAVE_KVM_IRQCHIP and HAVE_KVM_IRQ_ROUTING are defined.
KVM_CAP_IRQ_ROUTING is advertised and KVM_SET_GSI_ROUTING is allowed.

So from now on IRQCHIP routing is enabled and a routing table entry
must exist for irqfd injection to succeed for a given SPI. This patch
builds a default flat irqchip routing table (gsi=irqchip.pin) covering
all the VGIC SPI indexes. This routing table is overwritten by the
first first user-space call to KVM_SET_GSI_ROUTING ioctl.

MSI routing setup is not yet allowed.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Documentation/virtual/kvm/api.txt

@@ -1433,13 +1433,16 @@ KVM_ASSIGN_DEV_IRQ. Partial deassignment of host or guest IRQ is allowed.
 4.52 KVM_SET_GSI_ROUTING
 
 Capability: KVM_CAP_IRQ_ROUTING
-Architectures: x86 s390
+Architectures: x86 s390 arm arm64
 Type: vm ioctl
 Parameters: struct kvm_irq_routing (in)
 Returns: 0 on success, -1 on error
 
 Sets the GSI routing table entries, overwriting any previously set entries.
 
+On arm/arm64, GSI routing has the following limitation:
+- GSI routing does not apply to KVM_IRQ_LINE but only to KVM_IRQFD.
+
 struct kvm_irq_routing {
 	__u32 nr;
 	__u32 flags;
@@ -2374,9 +2377,10 @@ Note that closing the resamplefd is not sufficient to disable the
 irqfd.  The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
 and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.
 
-On ARM/ARM64, the gsi field in the kvm_irqfd struct specifies the Shared
-Peripheral Interrupt (SPI) index, such that the GIC interrupt ID is
-given by gsi + 32.
+On arm/arm64, gsi routing being supported, the following can happen:
+- in case no routing entry is associated to this gsi, injection fails
+- in case the gsi is associated to an irqchip routing entry,
+  irqchip.pin + 32 corresponds to the injected SPI ID.
 
 4.76 KVM_PPC_ALLOCATE_HTAB
 

arch/arm/kvm/Kconfig

@@ -32,6 +32,8 @@ config KVM
 	select KVM_VFIO
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_IRQFD
+	select HAVE_KVM_IRQCHIP
+	select HAVE_KVM_IRQ_ROUTING
 	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
 	---help---
 	  Support hosting virtualized guest machines.

arch/arm/kvm/Makefile

@@ -29,4 +29,5 @@ obj-y += $(KVM)/arm/vgic/vgic-v2.o
 obj-y += $(KVM)/arm/vgic/vgic-mmio.o
 obj-y += $(KVM)/arm/vgic/vgic-mmio-v2.o
 obj-y += $(KVM)/arm/vgic/vgic-kvm-device.o
+obj-y += $(KVM)/irqchip.o
 obj-y += $(KVM)/arm/arch_timer.o

arch/arm/kvm/irq.h

+/*
+ * irq.h: in kernel interrupt controller related definitions
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This header is included by irqchip.c. However, on ARM, interrupt
+ * controller declarations are located in include/kvm/arm_vgic.h since
+ * they are mostly shared between arm and arm64.
+ */
+
+#ifndef __IRQ_H
+#define __IRQ_H
+
+#include <kvm/arm_vgic.h>
+
+#endif

arch/arm64/kvm/Kconfig

@@ -37,6 +37,8 @@ config KVM
 	select KVM_ARM_VGIC_V3
 	select KVM_ARM_PMU if HW_PERF_EVENTS
 	select HAVE_KVM_MSI
+	select HAVE_KVM_IRQCHIP
+	select HAVE_KVM_IRQ_ROUTING
 	---help---
 	  Support hosting virtualized guest machines.
 	  We don't support KVM with 16K page tables yet, due to the multiple

arch/arm64/kvm/Makefile

@@ -30,5 +30,6 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v2.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v3.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-kvm-device.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-its.o
+kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
 kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o

arch/arm64/kvm/irq.h

+/*
+ * irq.h: in kernel interrupt controller related definitions
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This header is included by irqchip.c. However, on ARM, interrupt
+ * controller declarations are located in include/kvm/arm_vgic.h since
+ * they are mostly shared between arm and arm64.
+ */
+
+#ifndef __IRQ_H
+#define __IRQ_H
+
+#include <kvm/arm_vgic.h>
+
+#endif

include/kvm/arm_vgic.h

@@ -34,6 +34,7 @@
 #define VGIC_MAX_SPI		1019
 #define VGIC_MAX_RESERVED	1023
 #define VGIC_MIN_LPI		8192
+#define KVM_IRQCHIP_NUM_PINS	(1020 - 32)
 
 enum vgic_type {
 	VGIC_V2,		/* Good ol' GICv2 */
@@ -314,4 +315,10 @@ static inline int kvm_vgic_get_max_vcpus(void)
 
 int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
 
+/**
+ * kvm_vgic_setup_default_irq_routing:
+ * Setup a default flat gsi routing table mapping all SPIs
+ */
+int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
+
 #endif /* __KVM_ARM_VGIC_H */

virt/kvm/arm/vgic/vgic-init.c

@@ -264,6 +264,10 @@ int vgic_init(struct kvm *kvm)
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		kvm_vgic_vcpu_init(vcpu);
 
+	ret = kvm_vgic_setup_default_irq_routing(kvm);
+	if (ret)
+		goto out;
+
 	dist->initialized = true;
 out:
 	return ret;

virt/kvm/arm/vgic/vgic-irqfd.c

@@ -17,36 +17,100 @@
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 #include <trace/events/kvm.h>
+#include <kvm/arm_vgic.h>
+#include "vgic.h"
 
-int kvm_irq_map_gsi(struct kvm *kvm,
-		    struct kvm_kernel_irq_routing_entry *entries,
-		    int gsi)
+/**
+ * vgic_irqfd_set_irq: inject the IRQ corresponding to the
+ * irqchip routing entry
+ *
+ * This is the entry point for irqfd IRQ injection
+ */
+static int vgic_irqfd_set_irq(struct kvm_kernel_irq_routing_entry *e,
+			struct kvm *kvm, int irq_source_id,
+			int level, bool line_status)
 {
-	return 0;
+	unsigned int spi_id = e->irqchip.pin + VGIC_NR_PRIVATE_IRQS;
+
+	if (!vgic_valid_spi(kvm, spi_id))
+		return -EINVAL;
+	return kvm_vgic_inject_irq(kvm, 0, spi_id, level);
 }
 
-int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned int irqchip,
-			 unsigned int pin)
+/**
+ * kvm_set_routing_entry: populate a kvm routing entry
+ * from a user routing entry
+ *
+ * @e: kvm kernel routing entry handle
+ * @ue: user api routing entry handle
+ * return 0 on success, -EINVAL on errors.
+ */
+int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
+			  const struct kvm_irq_routing_entry *ue)
 {
-	return pin;
+	int r = -EINVAL;
+
+	switch (ue->type) {
+	case KVM_IRQ_ROUTING_IRQCHIP:
+		e->set = vgic_irqfd_set_irq;
+		e->irqchip.irqchip = ue->u.irqchip.irqchip;
+		e->irqchip.pin = ue->u.irqchip.pin;
+		if ((e->irqchip.pin >= KVM_IRQCHIP_NUM_PINS) ||
+		    (e->irqchip.irqchip >= KVM_NR_IRQCHIPS))
+			goto out;
+		break;
+	default:
+		goto out;
+	}
+	r = 0;
+out:
+	return r;
 }
 
-int kvm_set_irq(struct kvm *kvm, int irq_source_id,
-		u32 irq, int level, bool line_status)
+/**
+ * kvm_set_msi: inject the MSI corresponding to the
+ * MSI routing entry
+ *
+ * This is the entry point for irqfd MSI injection
+ * and userspace MSI injection.
+ */
+int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
+		struct kvm *kvm, int irq_source_id,
+		int level, bool line_status)
 {
-	unsigned int spi = irq + VGIC_NR_PRIVATE_IRQS;
+	struct kvm_msi msi;
 
-	trace_kvm_set_irq(irq, level, irq_source_id);
+	msi.address_lo = e->msi.address_lo;
+	msi.address_hi = e->msi.address_hi;
+	msi.data = e->msi.data;
+	msi.flags = e->msi.flags;
+	msi.devid = e->msi.devid;
 
-	BUG_ON(!vgic_initialized(kvm));
+	if (!vgic_has_its(kvm))
+		return -ENODEV;
 
-	return kvm_vgic_inject_irq(kvm, 0, spi, level);
+	return vgic_its_inject_msi(kvm, &msi);
 }
 
-/* MSI not implemented yet */
-int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
-		struct kvm *kvm, int irq_source_id,
-		int level, bool line_status)
+int kvm_vgic_setup_default_irq_routing(struct kvm *kvm)
 {
-	return 0;
+	struct kvm_irq_routing_entry *entries;
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	u32 nr = dist->nr_spis;
+	int i, ret;
+
+	entries = kcalloc(nr, sizeof(struct kvm_kernel_irq_routing_entry),
+			  GFP_KERNEL);
+	if (!entries)
+		return -ENOMEM;
+
+	for (i = 0; i < nr; i++) {
+		entries[i].gsi = i;
+		entries[i].type = KVM_IRQ_ROUTING_IRQCHIP;
+		entries[i].u.irqchip.irqchip = 0;
+		entries[i].u.irqchip.pin = i;
+	}
+	ret = kvm_set_irq_routing(kvm, entries, nr, 0);
+	kfree(entries);
+	return ret;
 }

virt/kvm/arm/vgic/vgic.c

@@ -711,10 +711,3 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq)
 	return map_is_active;
 }
 
-int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
-{
-	if (vgic_has_its(kvm))
-		return vgic_its_inject_msi(kvm, msi);
-	else
-		return -ENODEV;
-}