Re: [Qemu-devel] [PATCH 1/1 V2] kernel/kvm: fix improper nmi emulation

[Jan Kiszka <jan.kiszka@web.de>]

[-- Attachment #1: Type: text/plain, Size: 5347 bytes --]

[ dropped unaffected seabios from CC ]

On 2011-10-11 19:00, Lai Jiangshan wrote:
> From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
> 
> 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@jp.fujitsu.com>
> Tested-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
>  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

KVM_CAP_LAPIC_NMI needs to be listed here as well.

> +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.

Not sure if we document previous behaviour in the file as well. If we
do, the !KVM_CAP_LAPIC_NMI case requires some words.

> +
>  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

Unneeded #ifdef, that CAP is always available on x86.

> +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
>  
>  static int vcpu_ioctl_tpr_access_reporting(struct kvm_vcpu *vcpu,
>  					   struct kvm_tpr_access_ctl *tac)
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index aace6b8..5253a5c 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_CAP_USER_NMI

#ifdef __KVM_HAVE_USER_NMI

> +#define KVM_CAP_LAPIC_NMI 72
> +#endif
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 262 bytes --]