KVM: PPC: Book3S PR: Free shared page if mmu initialization fails

Explicitly free the shared page if kvmppc_mmu_init() fails during
kvmppc_core_vcpu_create(), as the page is freed only in
kvmppc_core_vcpu_free(), which is not reached via kvm_vcpu_uninit().

Fixes: 96bc451a ("KVM: PPC: Introduce shared page")
Cc: stable@vger.kernel.org
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Acked-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/powerpc/kvm/book3s_pr.c

@@ -1806,10 +1806,12 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_pr(struct kvm *kvm,
 
 	err = kvmppc_mmu_init(vcpu);
 	if (err < 0)
-		goto uninit_vcpu;
+		goto free_shared_page;
 
 	return vcpu;
 
+free_shared_page:
+	free_page((unsigned long)vcpu->arch.shared);
 uninit_vcpu:
 	kvm_vcpu_uninit(vcpu);
 free_shadow_vcpu: