Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor

From	Bandan Das <bsd@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor
Date	2017-07-12 20:10 +0200
Message-ID	<u2uff-3bm-13@gated-at.bofh.it> (permalink)
References	(6 earlier) <u28Rr-6kH-1@gated-at.bofh.it> <u29aO-6ru-31@gated-at.bofh.it> <u29Xc-6WM-17@gated-at.bofh.it> <u2agx-73x-1@gated-at.bofh.it> <u2qbD-pT-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Radim Krčmář <rkrcmar@redhat.com> writes:
...
>> > Thanks, we're not here to judge the guest, but to provide a bare-metal
>> > experience. :)
>> 
>> There are certain cases where do. For example, when L2 instruction emulation
>> fails we decide to kill L2 instead of injecting the error to L1 and let it handle
>> that. Anyway, that's a different topic, I was just trying to point out there
>> are cases kvm does a somewhat policy decision...
>
> Emulation failure is a KVM bug and we are too lazy to implement the
> bare-metal behavior correctly, but avoiding the EPTP list bug is
> actually easier than introducing it.  You can make KVM simpler and
> improve bare-metal emulation at the same time.

We are just talking past each other here trying to impose point of views.
Checking for 0 makes KVM simpler. As I said before, a 0 list_address means
that the hypervisor forgot to initialize it. Feel free to show me examples
where the hypervisor does indeed use a 0 address for eptp list address or
anything vm specific. You disagreed and I am fine with it.

Thread

[PATCH v4 0/3] Expose VMFUNC to the nested hypervisor Bandan Das <bsd@redhat.com> - 2017-07-10 23:00 +0200
  [PATCH v4 2/3] KVM: nVMX: Enable VMFUNC for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-10 23:00 +0200
  [PATCH v4 1/3] KVM: vmx: Enable VMFUNCs Bandan Das <bsd@redhat.com> - 2017-07-10 23:00 +0200
  [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-10 23:00 +0200
    Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor David Hildenbrand <david@redhat.com> - 2017-07-11 10:00 +0200
      Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Paolo Bonzini <pbonzini@redhat.com> - 2017-07-11 10:50 +0200
      Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 16:00 +0200
        Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 20:10 +0200
          Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 21:20 +0200
            Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 21:40 +0200
      Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 20:00 +0200
        Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 20:30 +0200
          Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 21:40 +0200
            Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 22:00 +0200
              Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 22:30 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 22:40 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 22:50 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 23:10 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-12 15:30 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-12 20:20 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-12 21:20 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-17 20:00 +0200
        Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Jim Mattson <jmattson@google.com> - 2017-07-11 20:30 +0200
          Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 20:40 +0200
            Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 21:20 +0200
              Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 21:40 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-11 22:30 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-11 22:50 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor Radim Krčmář <rkrcmar@redhat.com> - 2017-07-12 15:50 +0200
                Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-12 20:10 +0200
        Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1  hypervisor David Hildenbrand <david@redhat.com> - 2017-07-13 17:50 +0200
          Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Bandan Das <bsd@redhat.com> - 2017-07-13 19:10 +0200

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