Re: [PATCH] kvm/vmx: EPTP switching test

From	Paolo Bonzini <pbonzini@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] kvm/vmx: EPTP switching test
Date	2015-11-17 10:30 +0100
Message-ID	<qvKKm-397-19@gated-at.bofh.it> (permalink)
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On 16/11/2015 19:18, =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= wrote:
>> > No idea how would I even test it, so I'm not interested in #VE at this
>> > point.  If you are - go ahead and post a patch for that on top though,
>> > why not.
> I thought that it's going to be simpler to provide functionality (that
> utilizes eptp switching) to the guest through #VE, which probably isn't
> true as I think more about it.  (Not interested in implementing it :])

#VE and EPTP switching are distinct features, one does not imply the other.

Unfortunately, EPTP switching is designed for a very specific use case
where the hypervisor is effectively part of the kernel, and the kernel
is trusted to some extent.  Examples include antivirus software and
virtual machines.  Antiviruses do use VMFUNC, that's as far as I know
the only current use case of it
(https://embedded.communities.intel.com/community/en/applications/blog/2013/06/13/roving-reporter-enhancing-retail-security-and-manageability-with-4th-generation-intel-core-processors).

So I'm against this patch, but only because I'm not sure why KVM would
ever use EPTP switching in its current incarnation.  The guest kernel is
absolutely not trusted by KVM.

Paolo
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Re: [PATCH] kvm/vmx: EPTP switching test =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com> - 2015-11-16 19:00 +0100
  Re: [PATCH] kvm/vmx: EPTP switching test "Michael S. Tsirkin" <mst@redhat.com> - 2015-11-16 19:10 +0100
    Re: [PATCH] kvm/vmx: EPTP switching test =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com> - 2015-11-16 19:20 +0100
      Re: [PATCH] kvm/vmx: EPTP switching test Andy Lutomirski <luto@amacapital.net> - 2015-11-16 20:00 +0100
      Re: [PATCH] kvm/vmx: EPTP switching test Paolo Bonzini <pbonzini@redhat.com> - 2015-11-17 10:30 +0100

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