x86/paravirt/xen: properly fill out the ldt ops

LTP testing showed that Xen does not properly implement
sys_modify_ldt().  This patch does the final little bits needed to
make the ldt work properly.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index fbbde93..db9b064 100644
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -124,6 +124,9 @@
 				int entrynum, const void *desc, int size);
 	void (*write_idt_entry)(gate_desc *,
 				int entrynum, const gate_desc *gate);
+	void (*alloc_ldt)(struct desc_struct *ldt, unsigned entries);
+	void (*free_ldt)(struct desc_struct *ldt, unsigned entries);
+
 	void (*load_sp0)(struct tss_struct *tss, struct thread_struct *t);
 
 	void (*set_iopl_mask)(unsigned mask);
@@ -824,6 +827,16 @@
 	(aux) = __aux;					\
 } while (0)
 
+static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
+{
+	PVOP_VCALL2(pv_cpu_ops.alloc_ldt, ldt, entries);
+}
+
+static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
+{
+	PVOP_VCALL2(pv_cpu_ops.free_ldt, ldt, entries);
+}
+
 static inline void load_TR_desc(void)
 {
 	PVOP_VCALL0(pv_cpu_ops.load_tr_desc);