LoongArch: KVM: Add DMSINTC device support

Add device model for DMSINTC interrupt controller, implement basic
create/destroy/set_attr interfaces, and register device model to kvm
device table.

Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/include/asm/kvm_dmsintc.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2025 Loongson Technology Corporation Limited
+ */
+
+#ifndef __ASM_KVM_DMSINTC_H
+#define __ASM_KVM_DMSINTC_H
+
+#include <linux/kvm_types.h>
+
+struct loongarch_dmsintc {
+	struct kvm *kvm;
+	uint64_t msg_addr_base;
+	uint64_t msg_addr_size;
+	uint32_t cpu_mask;
+};
+
+struct dmsintc_state {
+	atomic64_t vector_map[4];
+};
+
+int kvm_loongarch_register_dmsintc_device(void);
+
+#endif

arch/loongarch/include/asm/kvm_host.h

@@ -20,6 +20,7 @@
 #include <asm/inst.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_ipi.h>
+#include <asm/kvm_dmsintc.h>
 #include <asm/kvm_eiointc.h>
 #include <asm/kvm_pch_pic.h>
 #include <asm/loongarch.h>
@@ -133,6 +134,7 @@ struct kvm_arch {
 	s64 time_offset;
 	struct kvm_context __percpu *vmcs;
 	struct loongarch_ipi *ipi;
+	struct loongarch_dmsintc *dmsintc;
 	struct loongarch_eiointc *eiointc;
 	struct loongarch_pch_pic *pch_pic;
 };
@@ -247,6 +249,7 @@ struct kvm_vcpu_arch {
 	struct kvm_mp_state mp_state;
 	/* ipi state */
 	struct ipi_state ipi_state;
+	struct dmsintc_state dmsintc_state;
 	/* cpucfg */
 	u32 cpucfg[KVM_MAX_CPUCFG_REGS];
 

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

@@ -155,4 +155,8 @@ struct kvm_iocsr_entry {
 #define KVM_DEV_LOONGARCH_PCH_PIC_GRP_CTRL	        0x40000006
 #define KVM_DEV_LOONGARCH_PCH_PIC_CTRL_INIT	        0
 
+#define KVM_DEV_LOONGARCH_DMSINTC_GRP_CTRL		0x40000007
+#define KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_BASE		0x0
+#define KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_SIZE		0x1
+
 #endif /* __UAPI_ASM_LOONGARCH_KVM_H */

arch/loongarch/kvm/Makefile

@@ -17,6 +17,7 @@ kvm-y += tlb.o
 kvm-y += vcpu.o
 kvm-y += vm.o
 kvm-y += intc/ipi.o
+kvm-y += intc/dmsintc.o
 kvm-y += intc/eiointc.o
 kvm-y += intc/pch_pic.o
 kvm-y += irqfd.o

arch/loongarch/kvm/intc/dmsintc.c

@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_dmsintc.h>
+#include <asm/kvm_vcpu.h>
+
+static int kvm_dmsintc_ctrl_access(struct kvm_device *dev,
+				   struct kvm_device_attr *attr, bool is_write)
+{
+	int addr = attr->attr;
+	unsigned long cpu_bit, val;
+	void __user *data = (void __user *)attr->addr;
+	struct loongarch_dmsintc *s = dev->kvm->arch.dmsintc;
+
+	switch (addr) {
+	case KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_BASE:
+		if (is_write) {
+			if (copy_from_user(&val, data, sizeof(s->msg_addr_base)))
+				return -EFAULT;
+			if (s->msg_addr_base)
+				return -EFAULT; /* Duplicate setting are not allowed. */
+			if ((val & (BIT(AVEC_CPU_SHIFT) - 1)) != 0)
+				return -EINVAL;
+			s->msg_addr_base = val;
+			cpu_bit = find_first_bit((unsigned long *)&(s->msg_addr_base), 64) - AVEC_CPU_SHIFT;
+			cpu_bit = min(cpu_bit, AVEC_CPU_BIT);
+			s->cpu_mask = GENMASK(cpu_bit - 1, 0) & AVEC_CPU_MASK;
+		}
+		break;
+	case KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_SIZE:
+		if (is_write) {
+			if (copy_from_user(&val, data, sizeof(s->msg_addr_size)))
+				return -EFAULT;
+			if (s->msg_addr_size)
+				return -EFAULT; /*Duplicate setting are not allowed. */
+			s->msg_addr_size = val;
+		}
+		break;
+	default:
+		kvm_err("%s: unknown dmsintc register, addr = %d\n", __func__, addr);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int kvm_dmsintc_set_attr(struct kvm_device *dev,
+				struct kvm_device_attr *attr)
+{
+	switch (attr->group) {
+	case KVM_DEV_LOONGARCH_DMSINTC_GRP_CTRL:
+		return kvm_dmsintc_ctrl_access(dev, attr, true);
+	default:
+		kvm_err("%s: unknown group (%d)\n", __func__, attr->group);
+		return -EINVAL;
+	}
+}
+
+static int kvm_dmsintc_create(struct kvm_device *dev, u32 type)
+{
+	struct kvm *kvm;
+	struct loongarch_dmsintc *s;
+
+	if (!dev) {
+		kvm_err("%s: kvm_device ptr is invalid!\n", __func__);
+		return -EINVAL;
+	}
+
+	kvm = dev->kvm;
+	if (kvm->arch.dmsintc) {
+		kvm_err("%s: LoongArch DMSINTC has already been created!\n", __func__);
+		return -EINVAL;
+	}
+
+	s = kzalloc(sizeof(struct loongarch_dmsintc), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	s->kvm = kvm;
+	kvm->arch.dmsintc = s;
+
+	return 0;
+}
+
+static void kvm_dmsintc_destroy(struct kvm_device *dev)
+{
+
+	if (!dev || !dev->kvm || !dev->kvm->arch.dmsintc)
+		return;
+
+	kfree(dev->kvm->arch.dmsintc);
+	kfree(dev);
+}
+
+static struct kvm_device_ops kvm_dmsintc_dev_ops = {
+	.name = "kvm-loongarch-dmsintc",
+	.create = kvm_dmsintc_create,
+	.destroy = kvm_dmsintc_destroy,
+	.set_attr = kvm_dmsintc_set_attr,
+};
+
+int kvm_loongarch_register_dmsintc_device(void)
+{
+	return kvm_register_device_ops(&kvm_dmsintc_dev_ops, KVM_DEV_TYPE_LOONGARCH_DMSINTC);
+}

arch/loongarch/kvm/main.c

@@ -416,6 +416,12 @@ static int kvm_loongarch_env_init(void)
 
 	/* Register LoongArch PCH-PIC interrupt controller interface. */
 	ret = kvm_loongarch_register_pch_pic_device();
+	if (ret)
+		return ret;
+
+	/* Register LoongArch DMSINTC interrupt contrroller interface */
+	if (cpu_has_msgint)
+		ret = kvm_loongarch_register_dmsintc_device();
 
 	return ret;
 }

include/uapi/linux/kvm.h

@@ -1224,6 +1224,8 @@ enum kvm_device_type {
 #define KVM_DEV_TYPE_LOONGARCH_EIOINTC	KVM_DEV_TYPE_LOONGARCH_EIOINTC
 	KVM_DEV_TYPE_LOONGARCH_PCHPIC,
 #define KVM_DEV_TYPE_LOONGARCH_PCHPIC	KVM_DEV_TYPE_LOONGARCH_PCHPIC
+	KVM_DEV_TYPE_LOONGARCH_DMSINTC,
+#define KVM_DEV_TYPE_LOONGARCH_DMSINTC	KVM_DEV_TYPE_LOONGARCH_DMSINTC
 
 	KVM_DEV_TYPE_MAX,