1 files changed, 82 insertions, 9 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 046c1f23dd6e..a44d56e38bd1 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -58,6 +58,13 @@
 #include "multicalls.h"
 #include "mmu.h"
 
+/*
+ * Just beyond the highest usermode address.  STACK_TOP_MAX has a
+ * redzone above it, so round it up to a PGD boundary.
+ */
+#define USER_LIMIT      ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK)
+
+
 #define P2M_ENTRIES_PER_PAGE    (PAGE_SIZE / sizeof(unsigned long))
 #define TOP_ENTRIES             (MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE)
 
@@ -461,17 +468,45 @@ pud_t xen_make_pud(pudval_t pud)
         return native_make_pud(pud);
 }
 
-void xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
+pgd_t *xen_get_user_pgd(pgd_t *pgd)
 {
-        struct mmu_update u;
+        pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK);
+        unsigned offset = pgd - pgd_page;
+        pgd_t *user_ptr = NULL;
 
-        preempt_disable();
+        if (offset < pgd_index(USER_LIMIT)) {
+                struct page *page = virt_to_page(pgd_page);
+                user_ptr = (pgd_t *)page->private;
+                if (user_ptr)
+                        user_ptr += offset;
+        }
 
-        xen_mc_batch();
+        return user_ptr;
+}
+
+static void __xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
+{
+        struct mmu_update u;
 
         u.ptr = virt_to_machine(ptr).maddr;
         u.val = pgd_val_ma(val);
         extend_mmu_update(&u);
+}
+
+/*
+ * Raw hypercall-based set_pgd, intended for in early boot before
+ * there's a page structure.  This implies:
+ *  1. The only existing pagetable is the kernel's
+ *  2. It is always pinned
+ *  3. It has no user pagetable attached to it
+ */
+void __init xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
+{
+        preempt_disable();
+
+        xen_mc_batch();
+
+        __xen_set_pgd_hyper(ptr, val);
 
         xen_mc_issue(PARAVIRT_LAZY_MMU);
 
@@ -480,14 +515,28 @@ void xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
 
 void xen_set_pgd(pgd_t *ptr, pgd_t val)
 {
+        pgd_t *user_ptr = xen_get_user_pgd(ptr);
+
         /* If page is not pinned, we can just update the entry
            directly */
         if (!page_pinned(ptr)) {
                 *ptr = val;
+                if (user_ptr) {
+                        WARN_ON(page_pinned(user_ptr));
+                        *user_ptr = val;
+                }
                 return;
         }
 
-        xen_set_pgd_hyper(ptr, val);
+        /* If it's pinned, then we can at least batch the kernel and
+           user updates together. */
+        xen_mc_batch();
+
+        __xen_set_pgd_hyper(ptr, val);
+        if (user_ptr)
+                __xen_set_pgd_hyper(user_ptr, val);
+
+        xen_mc_issue(PARAVIRT_LAZY_MMU);
 }
 #endif  /* PAGETABLE_LEVELS == 4 */
 
@@ -526,7 +575,7 @@ static int pgd_walk(pgd_t *pgd, int (*func)(struct page *, enum pt_level),
          * space, which contains the Xen mappings.  On 32-bit these
          * will end up making a zero-sized hole and so is a no-op.
          */
-        hole_low = pgd_index(STACK_TOP_MAX + PGDIR_SIZE - 1);
+        hole_low = pgd_index(USER_LIMIT);
         hole_high = pgd_index(PAGE_OFFSET);
 
         pgdidx_limit = pgd_index(limit);
@@ -670,19 +719,31 @@ void xen_pgd_pin(pgd_t *pgd)
 {
         xen_mc_batch();
 
-        if (pgd_walk(pgd, pin_page, TASK_SIZE)) {
+        if (pgd_walk(pgd, pin_page, USER_LIMIT)) {
                 /* re-enable interrupts for kmap_flush_unused */
                 xen_mc_issue(0);
                 kmap_flush_unused();
                 xen_mc_batch();
         }
 
+#ifdef CONFIG_X86_64
+        {
+                pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+                xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
+
+                if (user_pgd) {
+                        pin_page(virt_to_page(user_pgd), PT_PGD);
+                        xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(user_pgd)));
+                }
+        }
+#else /* CONFIG_X86_32 */
 #ifdef CONFIG_X86_PAE
         /* Need to make sure unshared kernel PMD is pinnable */
         pin_page(virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])), PT_PMD);
 #endif
-
         xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd)));
+#endif /* CONFIG_X86_64 */
         xen_mc_issue(0);
 }
 
@@ -763,11 +824,23 @@ static void xen_pgd_unpin(pgd_t *pgd)
 
         xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
 
+#ifdef CONFIG_X86_64
+        {
+                pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+                if (user_pgd) {
+                        xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(user_pgd)));
+                        unpin_page(virt_to_page(user_pgd), PT_PGD);
+                }
+        }
+#endif
+
 #ifdef CONFIG_X86_PAE
         /* Need to make sure unshared kernel PMD is unpinned */
         pin_page(virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])), PT_PMD);
 #endif
-        pgd_walk(pgd, unpin_page, TASK_SIZE);
+
+        pgd_walk(pgd, unpin_page, USER_LIMIT);
 
         xen_mc_issue(0);
 }