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Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf

From Radim Krčmář <rkrcmar@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf
Date 2017-06-16 15:40 +0200
Message-ID <tSZDH-Ds-3@gated-at.bofh.it> (permalink)
References <tSsRr-52d-9@gated-at.bofh.it> <tSsRs-52d-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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2017-06-14 19:26-0700, Wanpeng Li:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> Add an async_page_fault field to vcpu->arch.exception to identify an async 
> page fault, and constructs the expected vm-exit information fields. Force 
> a nested VM exit from nested_vmx_check_exception() if the injected #PF 
> is async page fault.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> @@ -452,7 +452,11 @@ EXPORT_SYMBOL_GPL(kvm_complete_insn_gp);
>  void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
>  {
>  	++vcpu->stat.pf_guest;
> -	vcpu->arch.cr2 = fault->address;
> +	vcpu->arch.exception.async_page_fault = fault->async_page_fault;

I think we need to act as if arch.exception.async_page_fault was not
pending in kvm_vcpu_ioctl_x86_get_vcpu_events().  Otherwise, if we
migrate with pending async_page_fault exception, we'd inject it as a
normal #PF, which could confuse/kill the nested guest.

And kvm_vcpu_ioctl_x86_set_vcpu_events() should clean the flag for
sanity as well.

Thanks.

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Thread

[PATCH v2 0/4] KVM: async_pf: Fix async_pf exception injection Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
  [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
    Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-16 15:40 +0200
      Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-16 16:30 +0200
        Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-16 17:40 +0200
          Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-17 03:50 +0200
          Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-17 08:00 +0200
            Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Radim Krčmář <rkrcmar@redhat.com> - 2017-06-19 17:00 +0200
              Re: [PATCH v2 3/4] KVM: async_pf: Force a nested vmexit if the  injected #PF is async_pf Wanpeng Li <kernellwp@gmail.com> - 2017-06-19 23:50 +0200
  [PATCH v2 2/4] KVM: async_pf: Add L1 guest async_pf #PF vmexit handler Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200
  [PATCH v2 4/4] KVM: async_pf: Let host know whether the guest support delivery async_pf as #PF vmexit Wanpeng Li <kernellwp@gmail.com> - 2017-06-15 04:40 +0200

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