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Message-ID: <CAAhV-H5L3jP_Rve_3qkQ58CfnCKsWPDJTDDsWRMiFiQDp0pfHQ@mail.gmail.com>
Date: Fri, 19 Dec 2025 12:10:02 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: WANG Xuerui <kernel@...0n.name>
Cc: Song Gao <gaosong@...ngson.cn>, maobibo@...ngson.cn, kvm@...r.kernel.org,
loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/3] LongArch: KVM: Add DMSINTC device support
On Fri, Dec 19, 2025 at 11:20 AM WANG Xuerui <kernel@...0n.name> wrote:
>
> On 12/18/25 19:18, Song Gao wrote:
> > 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@...ngson.cn>
> > Signed-off-by: Song Gao <gaosong@...ngson.cn>
> > ---
> > arch/loongarch/include/asm/kvm_dmsintc.h | 21 +++++
> > arch/loongarch/include/asm/kvm_host.h | 3 +
> > arch/loongarch/include/uapi/asm/kvm.h | 4 +
> > arch/loongarch/kvm/Makefile | 1 +
> > arch/loongarch/kvm/intc/dmsintc.c | 110 +++++++++++++++++++++++
> > arch/loongarch/kvm/main.c | 5 ++
> > include/uapi/linux/kvm.h | 2 +
> > 7 files changed, 146 insertions(+)
> > create mode 100644 arch/loongarch/include/asm/kvm_dmsintc.h
> > create mode 100644 arch/loongarch/kvm/intc/dmsintc.c
> >
> > diff --git a/arch/loongarch/include/asm/kvm_dmsintc.h b/arch/loongarch/include/asm/kvm_dmsintc.h
> > new file mode 100644
> > index 000000000000..1d4f66996f3c
> > --- /dev/null
> > +++ b/arch/loongarch/include/asm/kvm_dmsintc.h
> > @@ -0,0 +1,21 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (C) 2025 Loongson Technology Corporation Limited
> > + */
> > +
> > +#ifndef __ASM_KVM_DMSINTC_H
> > +#define __ASM_KVM_DMSINTC_H
> > +
> > +
> > +struct loongarch_dmsintc {
> > + struct kvm *kvm;
> > + uint64_t msg_addr_base;
> > + uint64_t msg_addr_size;
> > +};
> > +
> > +struct dmsintc_state {
> > + atomic64_t vector_map[4];
> > +};
> > +
> > +int kvm_loongarch_register_dmsintc_device(void);
> > +#endif
> > diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
> > index e4fe5b8e8149..5e9e2af7312f 100644
> > --- a/arch/loongarch/include/asm/kvm_host.h
> > +++ b/arch/loongarch/include/asm/kvm_host.h
> > @@ -22,6 +22,7 @@
> > #include <asm/kvm_ipi.h>
> > #include <asm/kvm_eiointc.h>
> > #include <asm/kvm_pch_pic.h>
> > +#include <asm/kvm_dmsintc.h>
> > #include <asm/loongarch.h>
> >
> > #define __KVM_HAVE_ARCH_INTC_INITIALIZED
> > @@ -134,6 +135,7 @@ struct kvm_arch {
> > struct loongarch_ipi *ipi;
> > struct loongarch_eiointc *eiointc;
> > struct loongarch_pch_pic *pch_pic;
> > + struct loongarch_dmsintc *dmsintc;
> > };
> >
> > #define CSR_MAX_NUMS 0x800
> > @@ -244,6 +246,7 @@ 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];
> >
> > diff --git a/arch/loongarch/include/uapi/asm/kvm.h b/arch/loongarch/include/uapi/asm/kvm.h
> > index de6c3f18e40a..0a370d018b08 100644
> > --- a/arch/loongarch/include/uapi/asm/kvm.h
> > +++ b/arch/loongarch/include/uapi/asm/kvm.h
> > @@ -154,4 +154,8 @@ 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_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 */
> > diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile
> > index cb41d9265662..6e184e24443c 100644
> > --- a/arch/loongarch/kvm/Makefile
> > +++ b/arch/loongarch/kvm/Makefile
> > @@ -19,6 +19,7 @@ kvm-y += vm.o
> > kvm-y += intc/ipi.o
> > kvm-y += intc/eiointc.o
> > kvm-y += intc/pch_pic.o
> > +kvm-y += intc/dmsintc.o
> > kvm-y += irqfd.o
> >
> > CFLAGS_exit.o += $(call cc-disable-warning, override-init)
> > diff --git a/arch/loongarch/kvm/intc/dmsintc.c b/arch/loongarch/kvm/intc/dmsintc.c
> > new file mode 100644
> > index 000000000000..3fdea81a08c8
> > --- /dev/null
> > +++ b/arch/loongarch/kvm/intc/dmsintc.c
> > @@ -0,0 +1,110 @@
> > +// 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;
> > + void __user *data;
> > + struct loongarch_dmsintc *s = dev->kvm->arch.dmsintc;
> > + u64 tmp;
> > +
> > + data = (void __user *)attr->addr;
> > + switch (addr) {
> > + case KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_BASE:
> > + if (is_write) {
> > + if (copy_from_user(&tmp, data, sizeof(s->msg_addr_base)))
> > + return -EFAULT;
> > + if (s->msg_addr_base) {
> > + /* Duplicate setting are not allowed. */
> > + return -EFAULT;
> > + }
> > + if ((tmp & (BIT(AVEC_CPU_SHIFT) - 1)) == 0)
> > + s->msg_addr_base = tmp;
> > + else
> > + return -EFAULT;
> > + }
> > + break;
> > + case KVM_DEV_LOONGARCH_DMSINTC_MSG_ADDR_SIZE:
> > + if (is_write) {
> > + if (copy_from_user(&tmp, data, sizeof(s->msg_addr_size)))
> > + return -EFAULT;
> > + if (s->msg_addr_size) {
> > + /*Duplicate setting are not allowed. */
> > + return -EFAULT;
> > + }
> > + s->msg_addr_size = tmp;
> > + }
> > + 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_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);
> > +}
> > +
> > +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);
> > +}
> > diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> > index 80ea63d465b8..2e26d4fd9000 100644
> > --- a/arch/loongarch/kvm/main.c
> > +++ b/arch/loongarch/kvm/main.c
> > @@ -408,6 +408,11 @@ 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 */
> > + ret = kvm_loongarch_register_dmsintc_device();
> >
> > return ret;
> > }
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index dddb781b0507..7c56e7e36265 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -1209,6 +1209,8 @@ 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,
> >
>
> Not a single line explaining what "DMSINTC" is? I checked v1, v2, and
> v3, no documentation regarding DINTC or DMSINTC at all. We can see (and
> Huacai explained in v3 review comment) "MSINTC" means "message-signaled
> interrupt controller", but what does "D" mean? You may want to update
> Documentation/arch/loongarch/irq-chip-model.rst for that.
D means Direct, from the Loongson-3C6000 user manual.
Huacai
>
> --
> Regards,
> WANG "xen0n" Xuerui
>
> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
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