Re: [PATCH v3 1/4] KVM: nVMX: Rework interception of IRQs and NMIs

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

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On 2014-03-07 20:48, Paolo Bonzini wrote:
> Il 07/03/2014 20:03, Jan Kiszka ha scritto:
>> @@ -4631,22 +4631,8 @@ static void vmx_set_nmi_mask(struct kvm_vcpu
>> *vcpu, bool masked)
>>
>>  static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
>>  {
>> -    if (is_guest_mode(vcpu)) {
>> -        if (to_vmx(vcpu)->nested.nested_run_pending)
>> -            return 0;
>> -        if (nested_exit_on_nmi(vcpu)) {
>> -            nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
>> -                      NMI_VECTOR | INTR_TYPE_NMI_INTR |
>> -                      INTR_INFO_VALID_MASK, 0);
>> -            /*
>> -             * The NMI-triggered VM exit counts as injection:
>> -             * clear this one and block further NMIs.
>> -             */
>> -            vcpu->arch.nmi_pending = 0;
>> -            vmx_set_nmi_mask(vcpu, true);
>> -            return 0;
>> -        }
>> -    }
>> +    if (to_vmx(vcpu)->nested.nested_run_pending)
>> +        return 0;
>>
>>      if (!cpu_has_virtual_nmis() && to_vmx(vcpu)->soft_vnmi_blocked)
>>          return 0;
>> @@ -4658,19 +4644,8 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
>>
>>  static int vmx_interrupt_allowed(struct kvm_vcpu *vcpu)
>>  {
>> -    if (is_guest_mode(vcpu)) {
>> -        if (to_vmx(vcpu)->nested.nested_run_pending)
>> -            return 0;
>> -        if (nested_exit_on_intr(vcpu)) {
>> -            nested_vmx_vmexit(vcpu, EXIT_REASON_EXTERNAL_INTERRUPT,
>> -                      0, 0);
>> -            /*
>> -             * fall through to normal code, but now in L1, not L2
>> -             */
>> -        }
>> -    }
>> -
>> -    return (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
>> +    return (!to_vmx(vcpu)->nested.nested_run_pending &&
>> +        vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
>>          !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
>>              (GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS));
> 
> The checks on nested_run_pending are not needed anymore and can be
> replaced with a WARN_ON.  Otherwise,

Nope, that won't be correct: If we have a pending interrupt that L1 does
not intercept, we still trigger this condition legally.

Jan

> 
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> Paolo
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