Re: [Qemu-devel] [PATCH 1/1 V5] kernel/kvm: introduce KVM_SET_LINT1 and fix improper nmi emulation

[Lai Jiangshan <laijs@cn.fujitsu.com>]

On 10/14/2011 05:07 PM, Jan Kiszka wrote:
> On 2011-10-14 11:03, Lai Jiangshan wrote:
>> Currently, NMI interrupt is blindly sent to all the vCPUs when NMI
>> button event happens. This doesn't properly emulate real hardware on
>> which NMI button event triggers LINT1. Because of this, NMI is sent to
>> the processor even when LINT1 is masked in LVT. For example, this
>> causes the problem that kdump initiated by NMI sometimes doesn't work
>> on KVM, because kdump assumes NMI is masked on CPUs other than CPU0.
>>
>> With this patch, we introduce introduce KVM_SET_LINT1,
>> and we can use KVM_SET_LINT1 to correctly emulate NMI button
>> without change the old KVM_NMI behavior.
>>
>> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
>> Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
>> ---
>>  arch/x86/include/asm/kvm.h |    1 +
>>  arch/x86/kvm/irq.h         |    1 +
>>  arch/x86/kvm/lapic.c       |    7 +++++++
>>  arch/x86/kvm/x86.c         |    8 ++++++++
>>  include/linux/kvm.h        |    5 +++++
>>  5 files changed, 22 insertions(+), 0 deletions(-)
>> diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
>> index 4d8dcbd..88d0ac3 100644
>> --- a/arch/x86/include/asm/kvm.h
>> +++ b/arch/x86/include/asm/kvm.h
>> @@ -24,6 +24,7 @@
>>  #define __KVM_HAVE_DEBUGREGS
>>  #define __KVM_HAVE_XSAVE
>>  #define __KVM_HAVE_XCRS
>> +#define __KVM_HAVE_SET_LINT1
>>  
>>  /* Architectural interrupt line count. */
>>  #define KVM_NR_INTERRUPTS 256
>> diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
>> index 53e2d08..0c96315 100644
>> --- a/arch/x86/kvm/irq.h
>> +++ b/arch/x86/kvm/irq.h
>> @@ -95,6 +95,7 @@ void kvm_pic_reset(struct kvm_kpic_state *s);
>>  void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
>>  void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);
>>  void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu);
>> +void kvm_apic_lint1_deliver(struct kvm_vcpu *vcpu);
>>  void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu);
>>  void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu);
>>  void __kvm_migrate_timers(struct kvm_vcpu *vcpu);
>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>> index 57dcbd4..87fe36a 100644
>> --- a/arch/x86/kvm/lapic.c
>> +++ b/arch/x86/kvm/lapic.c
>> @@ -1039,6 +1039,13 @@ void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu)
>>  		kvm_apic_local_deliver(apic, APIC_LVT0);
>>  }
>>  
>> +void kvm_apic_lint1_deliver(struct kvm_vcpu *vcpu)
>> +{
>> +	struct kvm_lapic *apic = vcpu->arch.apic;
>> +
>> +	kvm_apic_local_deliver(apic, APIC_LVT1);
>> +}
>> +
>>  static struct kvm_timer_ops lapic_timer_ops = {
>>  	.is_periodic = lapic_is_periodic,
>>  };
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 84a28ea..fccd094 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -2077,6 +2077,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>>  	case KVM_CAP_XSAVE:
>>  	case KVM_CAP_ASYNC_PF:
>>  	case KVM_CAP_GET_TSC_KHZ:
>> +	case KVM_CAP_SET_LINT1:
>>  		r = 1;
>>  		break;
>>  	case KVM_CAP_COALESCED_MMIO:
>> @@ -3264,6 +3265,13 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>>  
>>  		goto out;
>>  	}
>> +	case KVM_SET_LINT1: {
>> +		r = -EINVAL;
>> +		if (!irqchip_in_kernel(vcpu->kvm))
>> +			goto out;
>> +		r = 0;
>> +		kvm_apic_lint1_deliver(vcpu);
>> +	}
>>  	default:
>>  		r = -EINVAL;
>>  	}
>> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
>> index aace6b8..3a10572 100644
>> --- a/include/linux/kvm.h
>> +++ b/include/linux/kvm.h
>> @@ -554,6 +554,9 @@ struct kvm_ppc_pvinfo {
>>  #define KVM_CAP_PPC_SMT 64
>>  #define KVM_CAP_PPC_RMA	65
>>  #define KVM_CAP_S390_GMAP 71
>> +#ifdef __KVM_HAVE_SET_LINT1
>> +#define KVM_CAP_SET_LINT1 72
>> +#endif
> 
> Actually, there is no need for __KVM_HAVE_SET_LINT1 and #ifdef. User
> land will just do a runtime check.
> 
>

There is not bad result brought by __KVM_HAVE_SET_LINT1
and help for compile time check.

Thanks,
Lai