Re: [PATCH v6 2/2] LongArch: KVM: Add dmsintc inject msi to the dest vcpu

[gaosong <gaosong@loongson.cn>]

在 2026/3/5 下午3:33, Huacai Chen 写道:
> Hi, Song,
>
> On Fri, Feb 6, 2026 at 9:45 AM Song Gao <gaosong@loongson.cn> wrote:
>> Implement irqfd deliver msi to vcpu and vcpu dmsintc inject irq.
>> Add irqfd choice dmsintc to set msi irq by the msg_addr and
>> implement dmsintc set msi irq.
>>
>> Signed-off-by: Song Gao <gaosong@loongson.cn>
>> ---
>>   arch/loongarch/include/asm/kvm_dmsintc.h |  1 +
>>   arch/loongarch/include/asm/kvm_host.h    |  5 ++
>>   arch/loongarch/kvm/intc/dmsintc.c        |  6 +++
>>   arch/loongarch/kvm/interrupt.c           |  1 +
>>   arch/loongarch/kvm/irqfd.c               | 42 +++++++++++++++--
>>   arch/loongarch/kvm/vcpu.c                | 58 ++++++++++++++++++++++++
>>   6 files changed, 109 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/kvm_dmsintc.h b/arch/loongarch/include/asm/kvm_dmsintc.h
>> index 1d4f66996f3c..9b5436a2fcbe 100644
>> --- a/arch/loongarch/include/asm/kvm_dmsintc.h
>> +++ b/arch/loongarch/include/asm/kvm_dmsintc.h
>> @@ -11,6 +11,7 @@ struct loongarch_dmsintc  {
>>          struct kvm *kvm;
>>          uint64_t msg_addr_base;
>>          uint64_t msg_addr_size;
>> +       uint32_t cpu_mask;
>>   };
>>
>>   struct dmsintc_state {
>> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
>> index 5e9e2af7312f..91e0190aeaec 100644
>> --- a/arch/loongarch/include/asm/kvm_host.h
>> +++ b/arch/loongarch/include/asm/kvm_host.h
>> @@ -258,6 +258,11 @@ struct kvm_vcpu_arch {
>>          } st;
>>   };
>>
>> +void loongarch_dmsintc_inject_irq(struct kvm_vcpu *vcpu);
>> +int kvm_loongarch_deliver_msi_to_vcpu(struct kvm *kvm,
>> +                               struct kvm_vcpu *vcpu,
>> +                               u32 vector, int level);
>> +
>>   static inline unsigned long readl_sw_gcsr(struct loongarch_csrs *csr, int reg)
>>   {
>>          return csr->csrs[reg];
>> diff --git a/arch/loongarch/kvm/intc/dmsintc.c b/arch/loongarch/kvm/intc/dmsintc.c
>> index 00e401de0464..1bb61e55d061 100644
>> --- a/arch/loongarch/kvm/intc/dmsintc.c
>> +++ b/arch/loongarch/kvm/intc/dmsintc.c
>> @@ -15,6 +15,7 @@ static int kvm_dmsintc_ctrl_access(struct kvm_device *dev,
>>          void __user *data;
>>          struct loongarch_dmsintc *s = dev->kvm->arch.dmsintc;
>>          u64 tmp;
>> +       u32 cpu_bit;
>>
>>          data = (void __user *)attr->addr;
>>          switch (addr) {
>> @@ -30,6 +31,11 @@ static int kvm_dmsintc_ctrl_access(struct kvm_device *dev,
>>                                  s->msg_addr_base = tmp;
>>                          else
>>                                  return  -EFAULT;
>> +                       s->msg_addr_base = tmp;
>> +                       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:
> I'm not sure but maybe this part should go to the first patch?
I'll move it to patch1.
>> diff --git a/arch/loongarch/kvm/interrupt.c b/arch/loongarch/kvm/interrupt.c
>> index a6d42d399a59..893a81ca1079 100644
>> --- a/arch/loongarch/kvm/interrupt.c
>> +++ b/arch/loongarch/kvm/interrupt.c
>> @@ -33,6 +33,7 @@ static int kvm_irq_deliver(struct kvm_vcpu *vcpu, unsigned int priority)
>>                  irq = priority_to_irq[priority];
>>
>>          if (cpu_has_msgint && (priority == INT_AVEC)) {
>> +               loongarch_dmsintc_inject_irq(vcpu);
>>                  set_gcsr_estat(irq);
>>                  return 1;
>>          }
>> diff --git a/arch/loongarch/kvm/irqfd.c b/arch/loongarch/kvm/irqfd.c
>> index 9a39627aecf0..3bbb26f4e2b7 100644
>> --- a/arch/loongarch/kvm/irqfd.c
>> +++ b/arch/loongarch/kvm/irqfd.c
>> @@ -6,6 +6,7 @@
>>   #include <linux/kvm_host.h>
>>   #include <trace/events/kvm.h>
>>   #include <asm/kvm_pch_pic.h>
>> +#include <asm/kvm_vcpu.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)
>> @@ -16,6 +17,38 @@ static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
>>          return 0;
>>   }
>>
>> +static int kvm_dmsintc_set_msi_irq(struct kvm *kvm, u32 addr, int data, int level)
>> +{
>> +       unsigned int virq, dest;
>> +       struct kvm_vcpu *vcpu;
>> +
>> +       virq = (addr >> AVEC_IRQ_SHIFT) & AVEC_IRQ_MASK;
>> +       dest = (addr >> AVEC_CPU_SHIFT) & kvm->arch.dmsintc->cpu_mask;
>> +       if (dest > KVM_MAX_VCPUS)
>> +               return -EINVAL;
>> +       vcpu = kvm_get_vcpu_by_cpuid(kvm, dest);
>> +       if (!vcpu)
>> +               return -EINVAL;
>> +       return kvm_loongarch_deliver_msi_to_vcpu(kvm, vcpu, virq, level);
>> +}
>> +
>> +static int loongarch_set_msi(struct kvm_kernel_irq_routing_entry *e,
>> +                       struct kvm *kvm, int level)
>> +{
>> +       u64 msg_addr;
>> +
>> +       msg_addr = (((u64)e->msi.address_hi) << 32) | e->msi.address_lo;
>> +       if (cpu_has_msgint && kvm->arch.dmsintc &&
>> +               msg_addr >= kvm->arch.dmsintc->msg_addr_base &&
>> +               msg_addr < (kvm->arch.dmsintc->msg_addr_base  + kvm->arch.dmsintc->msg_addr_size)) {
>> +               return kvm_dmsintc_set_msi_irq(kvm, msg_addr, e->msi.data, level);
>> +       } else {
>> +               pch_msi_set_irq(kvm, e->msi.data, level);
>> +       }
>> +
>> +       return 0;
>> +}
> Rename loongarch_set_msi() to loongarch_msi_set_irq(), rename
> kvm_dmsintc_set_msi_irq() to dmsintc_msi_set_irq(), this makes the
> naming more consistent.
Got it .
>> +
>>   /*
>>    * kvm_set_msi: inject the MSI corresponding to the
>>    * MSI routing entry
>> @@ -29,9 +62,7 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
>>          if (!level)
>>                  return -1;
>>
>> -       pch_msi_set_irq(kvm, e->msi.data, level);
>> -
>> -       return 0;
>> +       return loongarch_set_msi(e, kvm, level);
>>   }
>>
>>   /*
>> @@ -71,12 +102,15 @@ int kvm_set_routing_entry(struct kvm *kvm,
>>   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)
>>   {
>> +       if (!level)
>> +               return -EWOULDBLOCK;
>> +
>>          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);
>> +               loongarch_set_msi(e, kvm, level);
>>                  return 0;
>>          default:
>>                  return -EWOULDBLOCK;
>> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
>> index 656b954c1134..325bb084d704 100644
>> --- a/arch/loongarch/kvm/vcpu.c
>> +++ b/arch/loongarch/kvm/vcpu.c
>> @@ -14,6 +14,64 @@
>>   #define CREATE_TRACE_POINTS
>>   #include "trace.h"
>>
>> +void loongarch_dmsintc_inject_irq(struct kvm_vcpu *vcpu)
>> +{
>> +       struct dmsintc_state *ds = &vcpu->arch.dmsintc_state;
>> +       unsigned int i;
>> +       unsigned long temp[4], old;
>> +
>> +       if (!ds)
>> +               return;
>> +
>> +       for (i = 0; i < 4; i++) {
>> +               old = atomic64_read(&(ds->vector_map[i]));
>> +               if (old)
>> +                       temp[i] = atomic64_xchg(&(ds->vector_map[i]), 0);
>> +       }
>> +
>> +       if (temp[0]) {
>> +               old = kvm_read_hw_gcsr(LOONGARCH_CSR_ISR0);
>> +               kvm_write_hw_gcsr(LOONGARCH_CSR_ISR0, temp[0]|old);
>> +       }
>> +
>> +       if (temp[1]) {
>> +               old = kvm_read_hw_gcsr(LOONGARCH_CSR_ISR1);
>> +               kvm_write_hw_gcsr(LOONGARCH_CSR_ISR1, temp[1]|old);
>> +       }
>> +
>> +       if (temp[2]) {
>> +               old = kvm_read_hw_gcsr(LOONGARCH_CSR_ISR2);
>> +               kvm_write_hw_gcsr(LOONGARCH_CSR_ISR2, temp[2]|old);
>> +       }
>> +
>> +       if (temp[3]) {
>> +               old = kvm_read_hw_gcsr(LOONGARCH_CSR_ISR3);
>> +               kvm_write_hw_gcsr(LOONGARCH_CSR_ISR3, temp[3]|old);
>> +       }
>> +}
> The only caller is in interrupt.c, so rename
> loongarch_dmsintc_inject_irq() to msgint_inject_irq() (or
> dmsintc_inject_irq() if you prefer), and move it to interrupt.c, then
> we don't need to declare it as a extern function.
Got it.
>> +
>> +int kvm_loongarch_deliver_msi_to_vcpu(struct kvm *kvm,
>> +                               struct kvm_vcpu *vcpu,
>> +                               u32 vector, int level)
>> +{
>> +       struct kvm_interrupt vcpu_irq;
>> +       struct dmsintc_state *ds;
>> +
>> +       if (!level)
>> +               return 0;
>> +       if (!vcpu || vector >= 256)
>> +               return -EINVAL;
>> +       ds = &vcpu->arch.dmsintc_state;
>> +       if (!ds)
>> +               return -ENODEV;
>> +       set_bit(vector, (unsigned long *)&ds->vector_map);
>> +       vcpu_irq.irq = INT_AVEC;
>> +       kvm_vcpu_ioctl_interrupt(vcpu, &vcpu_irq);
>> +       kvm_vcpu_kick(vcpu);
>> +       return 0;
>> +}
> The only caller is in irqfd.c, so rename
> kvm_loongarch_deliver_msi_to_vcpu() to dmsintc_deliver_msi_to_vcpu(),
> and move it to irqfd.c, then we don't need to declare it as a extern
> function.
Got it .
> And in addition, from Documentation/arch/loongarch/irq-chip-model.rst,
> all msi irq are triggered from "pch_msi_irq", which means it is not
> reasonable to dispatch the dmsintc/pch_msi paths in
> loongarch_set_msi(). Instead, we should dispatch the dmsintc/eiointc
> paths in pch_msi_set_irq(), this needs a rework...

longarch_set_msi() is equivalent to what you mentioned as pch_msi_set_irq(). I will correct it in the next version.

Thanks.
Song Gao

>
> Huacai
>
>> +
>> +
>>   const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
>>          KVM_GENERIC_VCPU_STATS(),
>>          STATS_DESC_COUNTER(VCPU, int_exits),
>> --
>> 2.39.3
>>
>>