linux-kernel - Re: [PATCH v2 18/21] KVM: x86: Treat pending TRIPLE

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Date:   Wed, 06 Jul 2022 15:16:20 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Oliver Upton <oupton@...gle.com>,
        Peter Shier <pshier@...gle.com>
Subject: Re: [PATCH v2 18/21] KVM: x86: Treat pending TRIPLE_FAULT requests
 as pending exceptions

On Tue, 2022-06-14 at 20:47 +0000, Sean Christopherson wrote:
> Treat pending TRIPLE_FAULTS as pending exceptions.  A triple fault is an
> exception for all intents and purposes, it's just not tracked as such
> because there's no vector associated the exception.  E.g. if userspace
> were to set vcpu->request_interrupt_window while running L2 and L2 hit a
> triple fault, a triple fault nested VM-Exit should be synthesized to L1
> before exiting to userspace with KVM_EXIT_IRQ_WINDOW_OPEN.
> 
> Link: https://lore.kernel.org/all/YoVHAIGcFgJit1qp@google.com
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/x86.c | 3 ---
>  arch/x86/kvm/x86.h | 3 ++-
>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 63ee79da50df..8e54a074b7ff 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12477,9 +12477,6 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
>         if (kvm_xen_has_pending_events(vcpu))
>                 return true;
>  
> -       if (kvm_test_request(KVM_REQ_TRIPLE_FAULT, vcpu))
> -               return true;
> -
>         return false;
>  }
>  
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index eee259e387d3..078765287ec6 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -85,7 +85,8 @@ int kvm_check_nested_events(struct kvm_vcpu *vcpu);
>  static inline bool kvm_is_exception_pending(struct kvm_vcpu *vcpu)
>  {
>         return vcpu->arch.exception.pending ||
> -              vcpu->arch.exception_vmexit.pending;
> +              vcpu->arch.exception_vmexit.pending ||
> +              kvm_test_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>  }
>  
>  static inline void kvm_clear_exception_queue(struct kvm_vcpu *vcpu)


Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky