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Re: [PATCH 1/2] KVM: MMU: fix ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo

From Xiao Guangrong <guangrong.xiao@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/2] KVM: MMU: fix ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo
Date 2016-03-10 09:50 +0100
Message-ID <rb4sa-4iX-11@gated-at.bofh.it> (permalink)
References <raojg-hv-5@gated-at.bofh.it> <raojh-hv-33@gated-at.bofh.it>
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On 03/08/2016 07:44 PM, Paolo Bonzini wrote:
> Yes, all of these are needed. :) This is admittedly a bit odd, but
> kvm-unit-tests access.flat tests this if you run it with "-cpu host"
> and of course ept=0.
>
> KVM handles supervisor writes of a pte.u=0/pte.w=0/CR0.WP=0 page by
> setting U=0 and W=1 in the shadow PTE.  This will cause a user write
> to fault and a supervisor write to succeed (which is correct because
> CR0.WP=0).  A user read instead will flip U=0 to 1 and W=1 back to 0.

BTW, it should be pte.u = 1 where you mentioned above.

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[PATCH 0/2] KVM: MMU: fix ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 Paolo Bonzini <pbonzini@redhat.com> - 2016-03-08 12:50 +0100
  [PATCH 1/2] KVM: MMU: fix ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Paolo Bonzini <pbonzini@redhat.com> - 2016-03-08 12:50 +0100
    Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-03-10 09:30 +0100
      Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Paolo Bonzini <pbonzini@redhat.com> - 2016-03-10 11:10 +0100
        Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-03-10 13:20 +0100
          Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Paolo Bonzini <pbonzini@redhat.com> - 2016-03-10 13:30 +0100
      Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Paolo Bonzini <pbonzini@redhat.com> - 2016-03-10 11:50 +0100
    Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-03-10 09:50 +0100
      Re: [PATCH 1/2] KVM: MMU: fix  ept=0/pte.u=0/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo Paolo Bonzini <pbonzini@redhat.com> - 2016-03-10 11:10 +0100

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