[ Upstream commit 8c6de56a42e0c657955e12b882a81ef07d1d073e ]
kvm_steal_time_set_preempted() may accidentally clear KVM_VCPU_FLUSH_TLB bit if it is called more than once while VCPU is preempted.
This is part of CVE-2019-3016.
(This bug was also independently discovered by Jim Mattson jmattson@google.com)
Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Reviewed-by: Joao Martins joao.m.martins@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/x86.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 09f47c837c258..3aed03942d7d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3075,6 +3075,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) return;
+ if (vcpu->arch.st.steal.preempted) + return; + vcpu->arch.st.steal.preempted = 1;
kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,