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Message-ID: <2688b612-3ace-b1d2-b9d1-dd35d35919c5@loongson.cn>
Date: Tue, 1 Jul 2025 19:38:43 +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 2025/7/1 下午5:20, Huacai Chen wrote:
> On Mon, Jun 30, 2025 at 4:44 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>>
>>
>> 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.
> Can we use kvm_arch_irqchip_in_kernel() to detect?
No, it can not be used. kvm_arch_irqchip_in_kernel() is usable only when
irqchip is created in kernel, however kvm_arch_init_vm() is called when
VM is created.
VM is created always before kernel irqchip is created. So
kvm_arch_irqchip_in_kernel() will return false if it is called in
kvm_arch_init_vm().
Regards
Bibo Mao
>
>
> Huacai
>
>>
>> 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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