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KVM: nVMX: Set LDTR to its architecturally defined value on nested VM-Exit

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Set L1's LDTR on VM-Exit per the Intel SDM:

  The host-state area does not contain a selector field for LDTR. LDTR is
  established as follows on all VM exits: the selector is cleared to
  0000H, the segment is marked unusable and is otherwise undefined
  (although the base address is always canonical).

This is likely a benign bug since the LDTR is unusable, as it means the
L1 VMM is conditioned to reload its LDTR in order to function properly on
bare metal.

Fixes: 4704d0befb07 ("KVM: nVMX: Exiting from L2 to L1")
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-07-13 09:32:40 -07:00 committed by Paolo Bonzini
parent df37ed38e6
commit afc8de0118
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kvm/vmx/nested.c
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@ -4298,6 +4298,10 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
};
vmx_set_segment(vcpu, &seg, VCPU_SREG_TR);
memset(&seg, 0, sizeof(seg));
seg.unusable = 1;
vmx_set_segment(vcpu, &seg, VCPU_SREG_LDTR);
kvm_set_dr(vcpu, 7, 0x400);
vmcs_write64(GUEST_IA32_DEBUGCTL, 0);