1 files changed, 25 insertions, 58 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 9f5983b01ed9..b456b048eca9 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -163,6 +163,7 @@
 #include <linux/hash.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
+#include <linux/bootmem.h>
 
 #include <asm/cache.h>
 #include <asm/setup.h>
@@ -181,21 +182,20 @@ static void __init m2p_override_init(void);
 
 unsigned long xen_max_p2m_pfn __read_mostly;
 
+static unsigned long *p2m_mid_missing_mfn;
+static unsigned long *p2m_top_mfn;
+static unsigned long **p2m_top_mfn_p;
+
 /* Placeholders for holes in the address space */
 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
 
 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
 
 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_identity, P2M_MID_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_identity_mfn, P2M_MID_PER_PAGE);
 
 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
-RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
 
 /* For each I/O range remapped we may lose up to two leaf pages for the boundary
  * violations and three mid pages to cover up to 3GB. With
@@ -272,11 +272,11 @@ static void p2m_init(unsigned long *p2m)
  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
  *
  * This is called both at boot time, and after resuming from suspend:
- * - At boot time we're called very early, and must use extend_brk()
+ * - At boot time we're called rather early, and must use alloc_bootmem*()
  *   to allocate memory.
  *
  * - After resume we're called from within stop_machine, but the mfn
- *   tree should alreay be completely allocated.
+ *   tree should already be completely allocated.
  */
 void __ref xen_build_mfn_list_list(void)
 {
@@ -287,20 +287,17 @@ void __ref xen_build_mfn_list_list(void)
 
         /* Pre-initialize p2m_top_mfn to be completely missing */
         if (p2m_top_mfn == NULL) {
-                p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
+                p2m_mid_missing_mfn = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
-                p2m_mid_identity_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
-                p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity);
 
-                p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
+                p2m_top_mfn_p = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
                 p2m_top_mfn_p_init(p2m_top_mfn_p);
 
-                p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
+                p2m_top_mfn = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
                 p2m_top_mfn_init(p2m_top_mfn);
         } else {
                 /* Reinitialise, mfn's all change after migration */
                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
-                p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity);
         }
 
         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
@@ -328,10 +325,9 @@ void __ref xen_build_mfn_list_list(void)
                         /*
                          * XXX boot-time only!  We should never find
                          * missing parts of the mfn tree after
-                         * runtime.  extend_brk() will BUG if we call
-                         * it too late.
+                         * runtime.
                          */
-                        mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
+                        mid_mfn_p = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
 
                         p2m_top_mfn_p[topidx] = mid_mfn_p;
@@ -415,7 +411,6 @@ void __init xen_build_dynamic_phys_to_machine(void)
         m2p_override_init();
 }
 #ifdef CONFIG_X86_64
-#include <linux/bootmem.h>
 unsigned long __init xen_revector_p2m_tree(void)
 {
         unsigned long va_start;
@@ -477,7 +472,6 @@ unsigned long __init xen_revector_p2m_tree(void)
 
                         copy_page(new, mid_p);
                         p2m_top[topidx][mididx] = &mfn_list[pfn_free];
-                        p2m_top_mfn_p[topidx][mididx] = virt_to_mfn(&mfn_list[pfn_free]);
 
                         pfn_free += P2M_PER_PAGE;
 
@@ -538,12 +532,13 @@ static bool alloc_p2m(unsigned long pfn)
         unsigned topidx, mididx;
         unsigned long ***top_p, **mid;
         unsigned long *top_mfn_p, *mid_mfn;
+        unsigned long *p2m_orig;
 
         topidx = p2m_top_index(pfn);
         mididx = p2m_mid_index(pfn);
 
         top_p = &p2m_top[topidx];
-        mid = *top_p;
+        mid = ACCESS_ONCE(*top_p);
 
         if (mid == p2m_mid_missing) {
                 /* Mid level is missing, allocate a new one */
@@ -558,7 +553,7 @@ static bool alloc_p2m(unsigned long pfn)
         }
 
         top_mfn_p = &p2m_top_mfn[topidx];
-        mid_mfn = p2m_top_mfn_p[topidx];
+        mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
 
         BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 
@@ -566,6 +561,7 @@ static bool alloc_p2m(unsigned long pfn)
                 /* Separately check the mid mfn level */
                 unsigned long missing_mfn;
                 unsigned long mid_mfn_mfn;
+                unsigned long old_mfn;
 
                 mid_mfn = alloc_p2m_page();
                 if (!mid_mfn)
@@ -575,17 +571,19 @@ static bool alloc_p2m(unsigned long pfn)
 
                 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
                 mid_mfn_mfn = virt_to_mfn(mid_mfn);
-                if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
+                old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
+                if (old_mfn != missing_mfn) {
                         free_p2m_page(mid_mfn);
-                else
+                        mid_mfn = mfn_to_virt(old_mfn);
+                } else {
                         p2m_top_mfn_p[topidx] = mid_mfn;
+                }
         }
 
-        if (p2m_top[topidx][mididx] == p2m_identity ||
-            p2m_top[topidx][mididx] == p2m_missing) {
+        p2m_orig = ACCESS_ONCE(p2m_top[topidx][mididx]);
+        if (p2m_orig == p2m_identity || p2m_orig == p2m_missing) {
                 /* p2m leaf page is missing */
                 unsigned long *p2m;
-                unsigned long *p2m_orig = p2m_top[topidx][mididx];
 
                 p2m = alloc_p2m_page();
                 if (!p2m)
@@ -606,7 +604,6 @@ static bool __init early_alloc_p2m(unsigned long pfn, bool check_boundary)
 {
         unsigned topidx, mididx, idx;
         unsigned long *p2m;
-        unsigned long *mid_mfn_p;
 
         topidx = p2m_top_index(pfn);
         mididx = p2m_mid_index(pfn);
@@ -633,43 +630,21 @@ static bool __init early_alloc_p2m(unsigned long pfn, bool check_boundary)
 
         p2m_top[topidx][mididx] = p2m;
 
-        /* For save/restore we need to MFN of the P2M saved */
-
-        mid_mfn_p = p2m_top_mfn_p[topidx];
-        WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing),
-                "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n",
-                topidx, mididx);
-        mid_mfn_p[mididx] = virt_to_mfn(p2m);
-
         return true;
 }
 
 static bool __init early_alloc_p2m_middle(unsigned long pfn)
 {
         unsigned topidx = p2m_top_index(pfn);
-        unsigned long *mid_mfn_p;
         unsigned long **mid;
 
         mid = p2m_top[topidx];
-        mid_mfn_p = p2m_top_mfn_p[topidx];
         if (mid == p2m_mid_missing) {
                 mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
 
                 p2m_mid_init(mid, p2m_missing);
 
                 p2m_top[topidx] = mid;
-
-                BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
-        }
-        /* And the save/restore P2M tables.. */
-        if (mid_mfn_p == p2m_mid_missing_mfn) {
-                mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
-                p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
-
-                p2m_top_mfn_p[topidx] = mid_mfn_p;
-                p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
-                /* Note: we don't set mid_mfn_p[midix] here,
-                 * look in early_alloc_p2m() */
         }
         return true;
 }
@@ -680,14 +655,13 @@ static bool __init early_alloc_p2m_middle(unsigned long pfn)
  * replace the P2M leaf with a p2m_missing or p2m_identity.
  * Stick the old page in the new P2M tree location.
  */
-bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
+static bool __init early_can_reuse_p2m_middle(unsigned long set_pfn)
 {
         unsigned topidx;
         unsigned mididx;
         unsigned ident_pfns;
         unsigned inv_pfns;
         unsigned long *p2m;
-        unsigned long *mid_mfn_p;
         unsigned idx;
         unsigned long pfn;
 
@@ -733,11 +707,6 @@ bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_
 found:
         /* Found one, replace old with p2m_identity or p2m_missing */
         p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
-        /* And the other for save/restore.. */
-        mid_mfn_p = p2m_top_mfn_p[topidx];
-        /* NOTE: Even if it is a p2m_identity it should still be point to
-         * a page filled with INVALID_P2M_ENTRY entries. */
-        mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
 
         /* Reset where we want to stick the old page in. */
         topidx = p2m_top_index(set_pfn);
@@ -752,8 +721,6 @@ found:
 
         p2m_init(p2m);
         p2m_top[topidx][mididx] = p2m;
-        mid_mfn_p = p2m_top_mfn_p[topidx];
-        mid_mfn_p[mididx] = virt_to_mfn(p2m);
 
         return true;
 }
@@ -763,7 +730,7 @@ bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
                 if (!early_alloc_p2m_middle(pfn))
                         return false;
 
-                if (early_can_reuse_p2m_middle(pfn, mfn))
+                if (early_can_reuse_p2m_middle(pfn))
                         return __set_phys_to_machine(pfn, mfn);
 
                 if (!early_alloc_p2m(pfn, false /* boundary crossover OK!*/))