Re: [PATCH v2] KVM: nVMX: Fix losing NMI blocking state

From	Paolo Bonzini <pbonzini@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] KVM: nVMX: Fix losing NMI blocking state
Date	2017-07-25 15:10 +0200
Message-ID	<u77L4-3dw-17@gated-at.bofh.it> (permalink)
References	<u75zA-1Fi-25@gated-at.bofh.it> <u75Jf-1Ip-3@gated-at.bofh.it> <u76lY-2cr-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 25/07/2017 13:36, Wanpeng Li wrote:
>>  - during VMRESUME emulation, prepare_vmcs02 sets bit 3 in the
>>    interruptibility-state field of vmcs02, but nmi_known_unmasked is
>>    still true.
>>  - on the next L2 exit to L0, nmi_known_unmasked is true so
>>    vmx_recover_nmi_blocking does not do anything.
>> 
>> Can you explain instead what happens if your v1 patch is applied (on top of mine),
>> and why it fixes the bug.
>
> We will set the expected guest interruptibility-state field before the
> final step: L0 fixes the shadow page table (NGVA -> HPA), then L0
> resumes the guest w/ the expected guest interruptibility-state.

Aha, that makes sense indeed!  I was confused between the first page
fault (that is reflected to L1) and the second (that is fixed by L0).

Thanks!

Paolo

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH v2] KVM: nVMX: Fix losing NMI blocking state Wanpeng Li <kernellwp@gmail.com> - 2017-07-25 12:50 +0200
  Re: [PATCH v2] KVM: nVMX: Fix losing NMI blocking state Paolo Bonzini <pbonzini@redhat.com> - 2017-07-25 13:00 +0200
    Re: [PATCH v2] KVM: nVMX: Fix losing NMI blocking state Wanpeng Li <kernellwp@gmail.com> - 2017-07-25 13:40 +0200
      Re: [PATCH v2] KVM: nVMX: Fix losing NMI blocking state Paolo Bonzini <pbonzini@redhat.com> - 2017-07-25 15:10 +0200

csiph-web