LoongArch: KVM: Add irqfd support

Enable the KVM_IRQ_ROUTING/KVM_IRQCHIP/KVM_MSI configuration items,
add the KVM_CAP_IRQCHIP capability, and implement the query interface
of the in-kernel irqchip.

Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Author: lixianglai

arch/loongarch/include/asm/kvm_host.h

@@ -23,6 +23,8 @@
 #include <asm/kvm_pch_pic.h>
 #include <asm/loongarch.h>
 
+#define __KVM_HAVE_ARCH_INTC_INITIALIZED
+
 /* Loongarch KVM register ids */
 #define KVM_GET_IOC_CSR_IDX(id)		((id & KVM_CSR_IDX_MASK) >> LOONGARCH_REG_SHIFT)
 #define KVM_GET_IOC_CPUCFG_IDX(id)	((id & KVM_CPUCFG_IDX_MASK) >> LOONGARCH_REG_SHIFT)

arch/loongarch/include/uapi/asm/kvm.h

@@ -8,6 +8,8 @@
 
 #include <linux/types.h>
 
+#define __KVM_HAVE_IRQ_LINE
+
 /*
  * KVM LoongArch specific structures and definitions.
  *

arch/loongarch/kvm/Kconfig

@@ -21,13 +21,16 @@ config KVM
 	tristate "Kernel-based Virtual Machine (KVM) support"
 	depends on AS_HAS_LVZ_EXTENSION
 	select HAVE_KVM_DIRTY_RING_ACQ_REL
+	select HAVE_KVM_IRQ_ROUTING
+	select HAVE_KVM_IRQCHIP
+	select HAVE_KVM_MSI
+	select HAVE_KVM_READONLY_MEM
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_COMMON
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select KVM_GENERIC_HARDWARE_ENABLING
 	select KVM_GENERIC_MMU_NOTIFIER
 	select KVM_MMIO
-	select HAVE_KVM_READONLY_MEM
 	select KVM_XFER_TO_GUEST_WORK
 	select SCHED_INFO
 	help

arch/loongarch/kvm/Makefile

@@ -21,5 +21,6 @@ kvm-y += vm.o
 kvm-y += intc/ipi.o
 kvm-y += intc/eiointc.o
 kvm-y += intc/pch_pic.o
+kvm-y += irqfd.o
 
 CFLAGS_exit.o	+= $(call cc-option,-Wno-override-init,)

arch/loongarch/kvm/intc/pch_pic.c

@@ -443,15 +443,42 @@ static int kvm_pch_pic_set_attr(struct kvm_device *dev,
 	}
 }
 
+static int kvm_setup_default_irq_routing(struct kvm *kvm)
+{
+	int i, ret;
+	u32 nr = KVM_IRQCHIP_NUM_PINS;
+	struct kvm_irq_routing_entry *entries;
+
+	entries = kcalloc(nr, sizeof(*entries), 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;
+}
+
 static int kvm_pch_pic_create(struct kvm_device *dev, u32 type)
 {
+	int ret;
 	struct kvm *kvm = dev->kvm;
 	struct loongarch_pch_pic *s;
 
 	/* pch pic should not has been created */
 	if (kvm->arch.pch_pic)
 		return -EINVAL;
 
+	ret = kvm_setup_default_irq_routing(kvm);
+	if (ret)
+		return -ENOMEM;
+
 	s = kzalloc(sizeof(struct loongarch_pch_pic), GFP_KERNEL);
 	if (!s)
 		return -ENOMEM;

arch/loongarch/kvm/irqfd.c

@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kvm_host.h>
+#include <trace/events/kvm.h>
+#include <asm/kvm_pch_pic.h>
+
+static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
+		struct kvm *kvm, int irq_source_id, int level, bool line_status)
+{
+	/* PCH-PIC pin (0 ~ 64) <---> GSI (0 ~ 64) */
+	pch_pic_set_irq(kvm->arch.pch_pic, e->irqchip.pin, level);
+
+	return 0;
+}
+
+/*
+ * 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)
+{
+	if (!level)
+		return -1;
+
+	pch_msi_set_irq(kvm, e->msi.data, level);
+
+	return 0;
+}
+
+/*
+ * kvm_set_routing_entry: populate a kvm routing entry
+ * from a user routing entry
+ *
+ * @kvm: the VM this entry is applied to
+ * @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 *kvm,
+			struct kvm_kernel_irq_routing_entry *e,
+			const struct kvm_irq_routing_entry *ue)
+{
+	switch (ue->type) {
+	case KVM_IRQ_ROUTING_IRQCHIP:
+		e->set = kvm_set_pic_irq;
+		e->irqchip.irqchip = ue->u.irqchip.irqchip;
+		e->irqchip.pin = ue->u.irqchip.pin;
+
+		if (e->irqchip.pin >= KVM_IRQCHIP_NUM_PINS)
+			return -EINVAL;
+
+		return 0;
+	case KVM_IRQ_ROUTING_MSI:
+		e->set = kvm_set_msi;
+		e->msi.address_lo = ue->u.msi.address_lo;
+		e->msi.address_hi = ue->u.msi.address_hi;
+		e->msi.data = ue->u.msi.data;
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e,
+		struct kvm *kvm, int irq_source_id, int level, bool line_status)
+{
+	switch (e->type) {
+	case KVM_IRQ_ROUTING_IRQCHIP:
+		pch_pic_set_irq(kvm->arch.pch_pic, e->irqchip.pin, level);
+		return 0;
+	case KVM_IRQ_ROUTING_MSI:
+		pch_msi_set_irq(kvm, e->msi.data, level);
+		return 0;
+	default:
+		return -EWOULDBLOCK;
+	}
+}
+
+bool kvm_arch_intc_initialized(struct kvm *kvm)
+{
+	return kvm_arch_irqchip_in_kernel(kvm);
+}

arch/loongarch/kvm/vm.c

@@ -6,6 +6,8 @@
 #include <linux/kvm_host.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_vcpu.h>
+#include <asm/kvm_eiointc.h>
+#include <asm/kvm_pch_pic.h>
 
 const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	KVM_GENERIC_VM_STATS(),
@@ -76,6 +78,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	int r;
 
 	switch (ext) {
+	case KVM_CAP_IRQCHIP:
 	case KVM_CAP_ONE_REG:
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_READONLY_MEM:
@@ -161,6 +164,8 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 	struct kvm_device_attr attr;
 
 	switch (ioctl) {
+	case KVM_CREATE_IRQCHIP:
+		return 0;
 	case KVM_HAS_DEVICE_ATTR:
 		if (copy_from_user(&attr, argp, sizeof(attr)))
 			return -EFAULT;
@@ -170,3 +175,19 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 		return -ENOIOCTLCMD;
 	}
 }
+
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event, bool line_status)
+{
+	if (!kvm_arch_irqchip_in_kernel(kvm))
+		return -ENXIO;
+
+	irq_event->status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
+					irq_event->irq, irq_event->level, line_status);
+
+	return 0;
+}
+
+bool kvm_arch_irqchip_in_kernel(struct kvm *kvm)
+{
+	return (kvm->arch.ipi && kvm->arch.eiointc && kvm->arch.pch_pic);
+}