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

BugLink: https://bugs.launchpad.net/bugs/1864775

commit cb10bf91 upstream.

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: Greg Kurz <groug@kaod.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/kvm/book3s_pr.c

@@ -1444,10 +1444,12 @@ 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: