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Message-ID: <31541826-2802-32e0-f8f0-f717e1c02d74@loongson.cn>
Date: Mon, 30 Jun 2025 16:43:06 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Tianrui Zhao <zhaotianrui@...ngson.cn>,
Xianglai Li <lixianglai@...ngson.cn>, kvm@...r.kernel.org,
loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] LoongArch: KVM: INTC: Add IOCSR MISC register
emulation
On 2025/6/30 下午4:04, Huacai Chen wrote:
> Hi, Bibo,
>
> On Thu, Jun 19, 2025 at 3:15 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>> IOCSR MISC register 0x420 controlls some features of eiointc, such as
>> BIT 48 enables eiointc and BIT 49 set interrupt encoding mode.
>>
>> When kernel irqchip is set, IOCSR MISC register should be emulated in
>> kernel also. Here add IOCSR MISC register emulation in kernel side.
>>
>> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
>> ---
>> v1 ... v2:
>> 1. Add separate file arch/loongarch/kvm/intc/misc.c for IOCSR MISC
>> register 0x420 emulation, since it controls feature about AVEC
>> irqchip also.
> I found we can decouple the misc register and EIOINTC in addition:
> 1, Move misc.c out of intc directory;
> 2, Call kvm_loongarch_create_misc() in kvm_arch_init_vm();
> 3, Call kvm_loongarch_destroy_misc() in kvm_arch_destroy_vm();
> 4, Then maybe misc_created can be removed.
Now irqchip in kernel is optional, the same with misc register. Misc
register will be emulated in user VMM if kernel-irqchip option is off.
There is no way to detect kernel-irqchip option when function
kvm_arch_init_vm() is called, and kvm_loongarch_create_misc() needs be
dynamically called from ioctl command.
Regards
Bibo Mao
>
> At last you can make this patch and others from another series to be a
> new series.
>
>
> Huacai
>
>>
>> 2. Define macro MISC_BASE as LOONGARCH_IOCSR_MISC_FUNC rather than
>> hard coded 0x420
>> ---
>> arch/loongarch/include/asm/kvm_eiointc.h | 2 +
>> arch/loongarch/include/asm/kvm_host.h | 2 +
>> arch/loongarch/include/asm/kvm_misc.h | 17 +++
>> arch/loongarch/include/asm/loongarch.h | 1 +
>> arch/loongarch/kvm/Makefile | 1 +
>> arch/loongarch/kvm/intc/eiointc.c | 61 +++++++++++
>> arch/loongarch/kvm/intc/misc.c | 125 +++++++++++++++++++++++
>> 7 files changed, 209 insertions(+)
>> create mode 100644 arch/loongarch/include/asm/kvm_misc.h
>> create mode 100644 arch/loongarch/kvm/intc/misc.c
>>
>> diff --git a/arch/loongarch/include/asm/kvm_eiointc.h b/arch/loongarch/include/asm/kvm_eiointc.h
>> index a3a40aba8acf..2d1c183f2b1b 100644
>> --- a/arch/loongarch/include/asm/kvm_eiointc.h
>> +++ b/arch/loongarch/include/asm/kvm_eiointc.h
>> @@ -119,5 +119,7 @@ struct loongarch_eiointc {
>>
>> int kvm_loongarch_register_eiointc_device(void);
>> void eiointc_set_irq(struct loongarch_eiointc *s, int irq, int level);
>> +int kvm_eiointc_get_status(struct kvm_vcpu *vcpu, unsigned long *value);
>> +int kvm_eiointc_update_status(struct kvm_vcpu *vcpu, unsigned long value, unsigned long mask);
>>
>> #endif /* __ASM_KVM_EIOINTC_H */
>> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
>> index a3c4cc46c892..f463ec52d86c 100644
>> --- a/arch/loongarch/include/asm/kvm_host.h
>> +++ b/arch/loongarch/include/asm/kvm_host.h
>> @@ -132,6 +132,8 @@ struct kvm_arch {
>> struct loongarch_ipi *ipi;
>> struct loongarch_eiointc *eiointc;
>> struct loongarch_pch_pic *pch_pic;
>> + struct kvm_io_device misc;
>> + bool misc_created;
>> };
>>
>> #define CSR_MAX_NUMS 0x800
>> diff --git a/arch/loongarch/include/asm/kvm_misc.h b/arch/loongarch/include/asm/kvm_misc.h
>> new file mode 100644
>> index 000000000000..621e4228dea2
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/kvm_misc.h
>> @@ -0,0 +1,17 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2025 Loongson Technology Corporation Limited
>> + */
>> +
>> +#ifndef __ASM_KVM_MISC_H
>> +#define __ASM_KVM_MISC_H
>> +
>> +#include <asm/loongarch.h>
>> +
>> +#define MISC_BASE LOONGARCH_IOCSR_MISC_FUNC
>> +#define MISC_SIZE 0x8
>> +
>> +int kvm_loongarch_create_misc(struct kvm *kvm);
>> +void kvm_loongarch_destroy_misc(struct kvm *kvm);
>> +
>> +#endif /* __ASM_KVM_MISC_H */
>> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
>> index d84dac88a584..e30d330d497e 100644
>> --- a/arch/loongarch/include/asm/loongarch.h
>> +++ b/arch/loongarch/include/asm/loongarch.h
>> @@ -1141,6 +1141,7 @@
>> #define IOCSR_MISC_FUNC_SOFT_INT BIT_ULL(10)
>> #define IOCSR_MISC_FUNC_TIMER_RESET BIT_ULL(21)
>> #define IOCSR_MISC_FUNC_EXT_IOI_EN BIT_ULL(48)
>> +#define IOCSR_MISC_FUNC_INT_ENCODE BIT_ULL(49)
>> #define IOCSR_MISC_FUNC_AVEC_EN BIT_ULL(51)
>>
>> #define LOONGARCH_IOCSR_CPUTEMP 0x428
>> diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile
>> index cb41d9265662..25fa3866613d 100644
>> --- a/arch/loongarch/kvm/Makefile
>> +++ b/arch/loongarch/kvm/Makefile
>> @@ -18,6 +18,7 @@ kvm-y += vcpu.o
>> kvm-y += vm.o
>> kvm-y += intc/ipi.o
>> kvm-y += intc/eiointc.o
>> +kvm-y += intc/misc.o
>> kvm-y += intc/pch_pic.o
>> kvm-y += irqfd.o
>>
>> diff --git a/arch/loongarch/kvm/intc/eiointc.c b/arch/loongarch/kvm/intc/eiointc.c
>> index f39929d7bf8a..87d01521e92f 100644
>> --- a/arch/loongarch/kvm/intc/eiointc.c
>> +++ b/arch/loongarch/kvm/intc/eiointc.c
>> @@ -4,6 +4,7 @@
>> */
>>
>> #include <asm/kvm_eiointc.h>
>> +#include <asm/kvm_misc.h>
>> #include <asm/kvm_vcpu.h>
>> #include <linux/count_zeros.h>
>>
>> @@ -708,6 +709,56 @@ static const struct kvm_io_device_ops kvm_eiointc_ops = {
>> .write = kvm_eiointc_write,
>> };
>>
>> +int kvm_eiointc_get_status(struct kvm_vcpu *vcpu, unsigned long *value)
>> +{
>> + unsigned long data, flags;
>> + struct loongarch_eiointc *eiointc = vcpu->kvm->arch.eiointc;
>> +
>> + if (!eiointc) {
>> + kvm_err("%s: eiointc irqchip not valid!\n", __func__);
>> + return -EINVAL;
>> + }
>> +
>> + data = 0;
>> + spin_lock_irqsave(&eiointc->lock, flags);
>> + if (eiointc->status & BIT(EIOINTC_ENABLE))
>> + data |= IOCSR_MISC_FUNC_EXT_IOI_EN;
>> +
>> + if (eiointc->status & BIT(EIOINTC_ENABLE_INT_ENCODE))
>> + data |= IOCSR_MISC_FUNC_INT_ENCODE;
>> + spin_unlock_irqrestore(&eiointc->lock, flags);
>> +
>> + *value = data;
>> + return 0;
>> +}
>> +
>> +int kvm_eiointc_update_status(struct kvm_vcpu *vcpu, unsigned long value, unsigned long mask)
>> +{
>> + struct loongarch_eiointc *eiointc = vcpu->kvm->arch.eiointc;
>> + unsigned long old, flags;
>> +
>> + if (!eiointc) {
>> + kvm_err("%s: eiointc irqchip not valid!\n", __func__);
>> + return -EINVAL;
>> + }
>> +
>> + old = 0;
>> + spin_lock_irqsave(&eiointc->lock, flags);
>> + if (eiointc->status & BIT(EIOINTC_ENABLE))
>> + old |= IOCSR_MISC_FUNC_EXT_IOI_EN;
>> + if (eiointc->status & BIT(EIOINTC_ENABLE_INT_ENCODE))
>> + old |= IOCSR_MISC_FUNC_INT_ENCODE;
>> +
>> + value |= (old & ~mask);
>> + eiointc->status &= ~(BIT(EIOINTC_ENABLE_INT_ENCODE) | BIT(EIOINTC_ENABLE));
>> + if (value & IOCSR_MISC_FUNC_INT_ENCODE)
>> + eiointc->status |= BIT(EIOINTC_ENABLE_INT_ENCODE);
>> + if (value & IOCSR_MISC_FUNC_EXT_IOI_EN)
>> + eiointc->status |= BIT(EIOINTC_ENABLE);
>> + spin_unlock_irqrestore(&eiointc->lock, flags);
>> + return 0;
>> +}
>> +
>> static int kvm_eiointc_virt_read(struct kvm_vcpu *vcpu,
>> struct kvm_io_device *dev,
>> gpa_t addr, int len, void *val)
>> @@ -993,6 +1044,15 @@ static int kvm_eiointc_create(struct kvm_device *dev, u32 type)
>> kfree(s);
>> return ret;
>> }
>> +
>> + ret = kvm_loongarch_create_misc(kvm);
>> + if (ret < 0) {
>> + kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &s->device);
>> + kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &s->device_vext);
>> + kfree(s);
>> + return ret;
>> + }
>> +
>> kvm->arch.eiointc = s;
>>
>> return 0;
>> @@ -1010,6 +1070,7 @@ static void kvm_eiointc_destroy(struct kvm_device *dev)
>> eiointc = kvm->arch.eiointc;
>> kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &eiointc->device);
>> kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &eiointc->device_vext);
>> + kvm_loongarch_destroy_misc(kvm);
>> kfree(eiointc);
>> }
>>
>> diff --git a/arch/loongarch/kvm/intc/misc.c b/arch/loongarch/kvm/intc/misc.c
>> new file mode 100644
>> index 000000000000..edee66afa36e
>> --- /dev/null
>> +++ b/arch/loongarch/kvm/intc/misc.c
>> @@ -0,0 +1,125 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2025 Loongson Technology Corporation Limited
>> + */
>> +#include <asm/kvm_vcpu.h>
>> +#include <asm/kvm_eiointc.h>
>> +#include <asm/kvm_misc.h>
>> +
>> +static int kvm_misc_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> + gpa_t addr, int len, void *val)
>> +{
>> + unsigned long data;
>> + unsigned int ret;
>> +
>> + addr -= MISC_BASE;
>> + if (addr & (len - 1)) {
>> + kvm_err("%s: eiointc not aligned addr %llx len %d\n", __func__, addr, len);
>> + return -EINVAL;
>> + }
>> +
>> + ret = kvm_eiointc_get_status(vcpu, &data);
>> + if (ret)
>> + return ret;
>> +
>> + data = data >> ((addr & 7) * 8);
>> + switch (len) {
>> + case 1:
>> + *(unsigned char *)val = (unsigned char)data;
>> + break;
>> +
>> + case 2:
>> + *(unsigned short *)val = (unsigned short)data;
>> + break;
>> +
>> + case 4:
>> + *(unsigned int *)val = (unsigned int)data;
>> + break;
>> +
>> + default:
>> + *(unsigned long *)val = data;
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int kvm_misc_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> + gpa_t addr, int len, const void *val)
>> +{
>> + unsigned long data, mask;
>> + unsigned int shift;
>> +
>> + addr -= MISC_BASE;
>> + if (addr & (len - 1)) {
>> + kvm_err("%s: eiointc not aligned addr %llx len %d\n", __func__, addr, len);
>> + return -EINVAL;
>> + }
>> +
>> + shift = (addr & 7) * 8;
>> + switch (len) {
>> + case 1:
>> + data = *(unsigned char *)val;
>> + mask = 0xFF;
>> + mask = mask << shift;
>> + data = data << shift;
>> + break;
>> +
>> + case 2:
>> + data = *(unsigned short *)val;
>> + mask = 0xFFFF;
>> + mask = mask << shift;
>> + data = data << shift;
>> + break;
>> +
>> + case 4:
>> + data = *(unsigned int *)val;
>> + mask = UINT_MAX;
>> + mask = mask << shift;
>> + data = data << shift;
>> + break;
>> +
>> + default:
>> + data = *(unsigned long *)val;
>> + mask = ULONG_MAX;
>> + mask = mask << shift;
>> + data = data << shift;
>> + break;
>> + }
>> +
>> + return kvm_eiointc_update_status(vcpu, data, mask);
>> +}
>> +
>> +static const struct kvm_io_device_ops kvm_misc_ops = {
>> + .read = kvm_misc_read,
>> + .write = kvm_misc_write,
>> +};
>> +
>> +int kvm_loongarch_create_misc(struct kvm *kvm)
>> +{
>> + struct kvm_io_device *device;
>> + int ret;
>> +
>> + if (kvm->arch.misc_created)
>> + return 0;
>> +
>> + device = &kvm->arch.misc;
>> + kvm_iodevice_init(device, &kvm_misc_ops);
>> + ret = kvm_io_bus_register_dev(kvm, KVM_IOCSR_BUS, MISC_BASE, MISC_SIZE, device);
>> + if (ret < 0)
>> + return ret;
>> +
>> + kvm->arch.misc_created = true;
>> + return 0;
>> +}
>> +
>> +void kvm_loongarch_destroy_misc(struct kvm *kvm)
>> +{
>> + struct kvm_io_device *device;
>> +
>> + if (kvm->arch.misc_created) {
>> + device = &kvm->arch.misc;
>> + kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, device);
>> + kvm->arch.misc_created = false;
>> + }
>> +}
>>
>> base-commit: 52da431bf03b5506203bca27fe14a97895c80faf
>> --
>> 2.39.3
>>
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