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>

1 files changed, 23 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 9ff6e3cbf08f..06219e60e9c8 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -325,6 +325,26 @@ static unsigned long xen_store_tr(void)
         return 0;
 }
 
+static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
+{
+        unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+        void *v = ldt;
+        int i;
+
+        for(i = 0; i < pages; i += PAGE_SIZE)
+                make_lowmem_page_readonly(v + i);
+}
+
+static void xen_free_ldt(struct desc_struct *ldt, unsigned entries)
+{
+        unsigned pages = roundup(entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+        void *v = ldt;
+        int i;
+
+        for(i = 0; i < pages; i += PAGE_SIZE)
+                make_lowmem_page_readwrite(v + i);
+}
+
 static void xen_set_ldt(const void *addr, unsigned entries)
 {
         struct mmuext_op *op;
@@ -1220,6 +1240,9 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
         .load_gs_index = xen_load_gs_index,
 #endif
 
+        .alloc_ldt = xen_alloc_ldt,
+        .free_ldt = xen_free_ldt,
+
         .store_gdt = native_store_gdt,
         .store_idt = native_store_idt,
         .store_tr = xen_store_tr,