From: Sean Christopherson seanjc@google.com

stable inclusion from stable-v5.15 commit afc8de0118be84f4058b9977d481aeb3e0758dbb category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6SN2F CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit afc8de0118be84f4058b9977d481aeb3e0758dbb upstream

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 Signed-off-by: rminmin renmm6@chinaunicom.cn --- arch/x86/kvm/vmx/nested.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 9003b14d72ca..05284589c14d 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4326,6 +4326,10 @@ 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);

-- 2.33.0

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