Unmap io shared page only if it is properly initialized.

Signed-off-by: Xin Li <xin.b.li@intel.com>

diff --git a/xen/arch/x86/vmx.c b/xen/arch/x86/vmx.c
index 6f087f8094fd6508ceb42856c6f49acb211a38c5..521f5fe15e2cd8dcdbea105b12f5d9e7263d8cc2 100644 (file)
--- a/xen/arch/x86/vmx.c
+++ b/xen/arch/x86/vmx.c
@@ -102,7 +102,8 @@ void vmx_relinquish_resources(struct vcpu *v)
     if (v->vcpu_id == 0) {
         /* unmap IO shared page */
         struct domain *d = v->domain;
-        unmap_domain_page((void *)d->arch.vmx_platform.shared_page_va);
+        if ( d->arch.vmx_platform.shared_page_va )
+            unmap_domain_page((void *)d->arch.vmx_platform.shared_page_va);
     }
 
     destroy_vmcs(&v->arch.arch_vmx);