[RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so)

From	Paolo Bonzini <pbonzini@redhat.com>
Newsgroups	linux.kernel
Subject	[RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so)
Date	2016-07-12 21:30 +0200
Message-ID	<rUbxw-Oh-21@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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UMIP (User-Mode Instruction Prevention) is a feature of future
Intel processors (Cannonlake?) that blocks SLDT, SGDT, STR, SIDT
and SMSW from user-mode processes.

The idea here is to use virtualization intercepts to emulate UMIP; it
slows down the instructions when they're executed in ring 0, but they
are really never executed in practice.  On AMD systems it's possible
to emulate it entirely; instead on Intel systems it's *almost* possible
to emulate it, because SMSW doesn't cause a vmexit, and hence SMSW will
not fault.

This patch series provides the infrastructure and implements it on
Intel.  I tested it through kvm-unit-tests.

Still I think the idea is interesting, even if it's buggy for current
Intel processors.  Any opinions?

Paolo

Paolo Bonzini (4):
  x86: add UMIP feature and CR4 bit
  KVM: x86: emulate sldt and str
  KVM: x86: add support for emulating UMIP
  KVM: vmx: add support for emulating UMIP

 arch/x86/include/asm/cpufeatures.h          |  1 +
 arch/x86/include/asm/kvm_host.h             |  3 ++-
 arch/x86/include/asm/vmx.h                  |  1 +
 arch/x86/include/uapi/asm/processor-flags.h |  2 ++
 arch/x86/include/uapi/asm/vmx.h             |  4 +++
 arch/x86/kvm/cpuid.c                        |  5 +++-
 arch/x86/kvm/cpuid.h                        |  8 ++++++
 arch/x86/kvm/emulate.c                      | 40 ++++++++++++++++++++++++-----
 arch/x86/kvm/svm.c                          |  6 +++++
 arch/x86/kvm/vmx.c                          | 40 ++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c                          |  3 +++
 11 files changed, 104 insertions(+), 9 deletions(-)

-- 
1.8.3.1

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[RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so) Paolo Bonzini <pbonzini@redhat.com> - 2016-07-12 21:30 +0200
  Re: [RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so) Yang Zhang <yang.zhang.wz@gmail.com> - 2016-07-13 10:40 +0200
    Re: [RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so) Paolo Bonzini <pbonzini@redhat.com> - 2016-07-13 11:40 +0200

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