KVM: MMU: Fix another largepage memory leak

In the paging_fetch function rmap_remove is called after setting a large
pte to non-present. This causes rmap_remove to not drop the reference to
the large page. The result is a memory leak of that page.

Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/paging_tmpl.h

@@ -306,9 +306,9 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 			continue;
 
 		if (is_large_pte(*sptep)) {
+			rmap_remove(vcpu->kvm, sptep);
 			set_shadow_pte(sptep, shadow_trap_nonpresent_pte);
 			kvm_flush_remote_tlbs(vcpu->kvm);
-			rmap_remove(vcpu->kvm, sptep);
 		}
 
 		if (level == PT_DIRECTORY_LEVEL