KVM: x86: fix typo in __try_cmpxchg_user causing non-atomicness

commit 33fbe6befa622c082f7d417896832856814bdde0 upstream.

This shows up as a TDP MMU leak when running nested.  Non-working cmpxchg on L0
relies makes L1 install two different shadow pages under same spte, and one of
them is leaked.

Fixes: 1c2361f667f36 ("KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220512101420.306759-1-mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f9802ce..bd41092 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6933,7 +6933,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
                goto emul_write;
 
        hva = kvm_vcpu_gfn_to_hva(vcpu, gpa_to_gfn(gpa));
-       if (kvm_is_error_hva(addr))
+       if (kvm_is_error_hva(hva))
                goto emul_write;
 
        hva += offset_in_page(gpa);