(2011/10/12 2:00), Lai Jiangshan wrote:
> From: Kenji Kaneshige<kaneshige.kenji@xxxxxxxxxxxxxx>
>
> 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 maskied 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, KVM_NMI ioctl is handled as follows.
>
> - When in-kernel irqchip is enabled, KVM_NMI ioctl is handled as a
> request of triggering LINT1 on the processor. LINT1 is emulated in
> in-kernel irqchip.
>
> - When in-kernel irqchip is disabled, KVM_NMI ioctl is handled as a
> request of injecting NMI to the processor. This assumes LINT1 is
> already emulated in userland.
>
> (laijs) Changed from v1:
> Add KVM_NMI API document
> Add KVM_CAP_USER_NMI
>
> Signed-off-by: Kenji Kaneshige<kaneshige.kenji@xxxxxxxxxxxxxx>
> Tested-by: Lai Jiangshan<laijs@xxxxxxxxxxxxxx>
> ---
> Documentation/virtual/kvm/api.txt | 20 ++++++++++++++++++++
> arch/x86/kvm/irq.h | 1 +
> arch/x86/kvm/lapic.c | 7 +++++++
> arch/x86/kvm/x86.c | 12 ++++++++++++
> include/linux/kvm.h | 3 +++
> 5 files changed, 43 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index b0e4b9c..5c24cc3 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1430,6 +1430,26 @@ is supported; 2 if the processor requires all virtual machines to have
> an RMA, or 1 if the processor can use an RMA but doesn't require it,
> because it supports the Virtual RMA (VRMA) facility.
>
> +4.64 KVM_NMI
> +
> +Capability: KVM_CAP_USER_NMI
> +Architectures: x86
> +Type: vcpu ioctl
> +Parameters: none
> +Returns: 0 on success, -1 on error
> +
> +This ioctl injects NMI to the vcpu.
> +
> +If with capability KVM_CAP_LAPIC_NMI, KVM_NMI ioctl is handled as follows:
> +
> + - When in-kernel irqchip is enabled, KVM_NMI ioctl is handled as a
> + request of triggering LINT1 on the processor. LINT1 is emulated in
> + in-kernel lapic irqchip.
> +
> + - When in-kernel irqchip is disabled, KVM_NMI ioctl is handled as a
> + request of injecting NMI to the processor. This assumes LINT1 is
> + already emulated in userland lapic.
> +
> 5. The kvm_run structure
>
> Application code obtains a pointer to the kvm_run structure by
> 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..6862ef7 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2729,12 +2729,24 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
> return 0;
> }
>
> +#ifdef KVM_CAP_LAPIC_NMI
> +static int kvm_vcpu_ioctl_nmi(struct kvm_vcpu *vcpu)
> +{
> + if (irqchip_in_kernel(vcpu->kvm))
> + kvm_apic_lint1_deliver(vcpu);
> + else
> + kvm_inject_nmi(vcpu);
> +
> + return 0;
> +}
> +#else
> static int kvm_vcpu_ioctl_nmi(struct kvm_vcpu *vcpu)
> {
> kvm_inject_nmi(vcpu);
>
> return 0;
> }
> +#endif
I don't think we need to keep old kvm_vcpu_ioctl_nmi() behavior because
it's clearly a bug.
Regards,
Kenji Kaneshige
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