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>

3 files changed, 35 insertions, 1 deletions

diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 3fee2aa50f3f..4895e0634d22 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -51,6 +51,8 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
         memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
                (mincount - oldsize) * LDT_ENTRY_SIZE);
 
+        paravirt_alloc_ldt(newldt, mincount);
+
 #ifdef CONFIG_X86_64
         /* CHECKME: Do we really need this ? */
         wmb();
@@ -75,6 +77,7 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
 #endif
         }
         if (oldsize) {
+                paravirt_free_ldt(oldldt, oldsize);
                 if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
                         vfree(oldldt);
                 else
@@ -86,10 +89,13 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
 static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
 {
         int err = alloc_ldt(new, old->size, 0);
+        int i;
 
         if (err < 0)
                 return err;
-        memcpy(new->ldt, old->ldt, old->size * LDT_ENTRY_SIZE);
+
+        for(i = 0; i < old->size; i++)
+                write_ldt_entry(new->ldt, i, old->ldt + i * LDT_ENTRY_SIZE);
         return 0;
 }
 
@@ -126,6 +132,7 @@ void destroy_context(struct mm_struct *mm)
                 if (mm == current->active_mm)
                         clear_LDT();
 #endif
+                paravirt_free_ldt(mm->context.ldt, mm->context.size);
                 if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
                         vfree(mm->context.ldt);
                 else
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 94da4d52d798..d8f2277be5a0 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -348,6 +348,10 @@ struct pv_cpu_ops pv_cpu_ops = {
         .write_ldt_entry = native_write_ldt_entry,
         .write_gdt_entry = native_write_gdt_entry,
         .write_idt_entry = native_write_idt_entry,
+
+        .alloc_ldt = paravirt_nop,
+        .free_ldt = paravirt_nop,
+
         .load_sp0 = native_load_sp0,
 
 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
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,