From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 19 Jan 2018 10:16:10 +0000 (+0100)
Subject: x86/shadow: widen reference count
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~734
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=97207ddd3b2bbbf6e723d8c5f2a93592a1cf5d81;p=xen.git

x86/shadow: widen reference count

Utilize as many of the bits available in the union as possible, without
(just to be on the safe side) colliding with any of the bits outside of
PGT_type_mask.

Note that the first and last hunks of the xen/include/asm-x86/mm.h
change are merely code motion.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/mm/shadow/private.h b/xen/arch/x86/mm/shadow/private.h
index 554905e87e..845541fe8a 100644
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -520,7 +520,7 @@ void sh_destroy_shadow(struct domain *d, mfn_t smfn);
  * Returns 0 for failure, 1 for success. */
 static inline int sh_get_ref(struct domain *d, mfn_t smfn, paddr_t entry_pa)
 {
-    u32 x, nx;
+    unsigned long x, nx;
     struct page_info *sp = mfn_to_page(smfn);
 
     ASSERT(mfn_valid(smfn));
@@ -529,7 +529,7 @@ static inline int sh_get_ref(struct domain *d, mfn_t smfn, paddr_t entry_pa)
     x = sp->u.sh.count;
     nx = x + 1;
 
-    if ( unlikely(nx >= (1U << PAGE_SH_REFCOUNT_WIDTH)) )
+    if ( unlikely(nx >= (1UL << PAGE_SH_REFCOUNT_WIDTH)) )
     {
         SHADOW_PRINTK("shadow ref overflow, gmfn=%lx smfn=%lx\n",
                        __backpointer(sp), mfn_x(smfn));
@@ -553,7 +553,7 @@ static inline int sh_get_ref(struct domain *d, mfn_t smfn, paddr_t entry_pa)
  * physical address of the shadow entry that held this reference. */
 static inline void sh_put_ref(struct domain *d, mfn_t smfn, paddr_t entry_pa)
 {
-    u32 x, nx;
+    unsigned long x, nx;
     struct page_info *sp = mfn_to_page(smfn);
 
     ASSERT(mfn_valid(smfn));
@@ -571,8 +571,8 @@ static inline void sh_put_ref(struct domain *d, mfn_t smfn, paddr_t entry_pa)
 
     if ( unlikely(x == 0) )
     {
-        SHADOW_ERROR("shadow ref underflow, smfn=%lx oc=%08x t=%#x\n",
-                     mfn_x(smfn), sp->u.sh.count, sp->u.sh.type);
+        SHADOW_ERROR("shadow ref underflow, smfn=%lx oc=%#lx t=%#x\n",
+                     mfn_x(smfn), sp->u.sh.count + 0UL, sp->u.sh.type);
         BUG();
     }
 
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 4af6b2341a..3013c266fe 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -18,6 +18,77 @@
  */
 #define PFN_ORDER(_pfn) ((_pfn)->v.free.order)
 
+#define PG_shift(idx)   (BITS_PER_LONG - (idx))
+#define PG_mask(x, idx) (x ## UL << PG_shift(idx))
+
+ /* The following page types are MUTUALLY EXCLUSIVE. */
+#define PGT_none          PG_mask(0, 3)  /* no special uses of this page   */
+#define PGT_l1_page_table PG_mask(1, 3)  /* using as an L1 page table?     */
+#define PGT_l2_page_table PG_mask(2, 3)  /* using as an L2 page table?     */
+#define PGT_l3_page_table PG_mask(3, 3)  /* using as an L3 page table?     */
+#define PGT_l4_page_table PG_mask(4, 3)  /* using as an L4 page table?     */
+#define PGT_seg_desc_page PG_mask(5, 3)  /* using this page in a GDT/LDT?  */
+#define PGT_shared_page   PG_mask(6, 3)  /* CoW sharable page              */
+#define PGT_writable_page PG_mask(7, 3)  /* has writable mappings?         */
+#define PGT_type_mask     PG_mask(7, 3)  /* Bits 61-63.                    */
+
+ /* Page is locked? */
+#define _PGT_locked       PG_shift(4)
+#define PGT_locked        PG_mask(1, 4)
+ /* Owning guest has pinned this page to its current type? */
+#define _PGT_pinned       PG_shift(5)
+#define PGT_pinned        PG_mask(1, 5)
+ /* Has this page been validated for use as its current type? */
+#define _PGT_validated    PG_shift(6)
+#define PGT_validated     PG_mask(1, 6)
+ /* PAE only: is this an L2 page directory containing Xen-private mappings? */
+#define _PGT_pae_xen_l2   PG_shift(7)
+#define PGT_pae_xen_l2    PG_mask(1, 7)
+/* Has this page been *partially* validated for use as its current type? */
+#define _PGT_partial      PG_shift(8)
+#define PGT_partial       PG_mask(1, 8)
+
+ /* Count of uses of this frame as its current type. */
+#define PGT_count_width   PG_shift(8)
+#define PGT_count_mask    ((1UL<<PGT_count_width)-1)
+
+/* Are the 'type mask' bits identical? */
+#define PGT_type_equal(x, y) (!(((x) ^ (y)) & PGT_type_mask))
+
+ /* Cleared when the owning guest 'frees' this page. */
+#define _PGC_allocated    PG_shift(1)
+#define PGC_allocated     PG_mask(1, 1)
+ /* Page is Xen heap? */
+#define _PGC_xen_heap     PG_shift(2)
+#define PGC_xen_heap      PG_mask(1, 2)
+ /* Set when is using a page as a page table */
+#define _PGC_page_table   PG_shift(3)
+#define PGC_page_table    PG_mask(1, 3)
+ /* 3-bit PAT/PCD/PWT cache-attribute hint. */
+#define PGC_cacheattr_base PG_shift(6)
+#define PGC_cacheattr_mask PG_mask(7, 6)
+ /* Page is broken? */
+#define _PGC_broken       PG_shift(7)
+#define PGC_broken        PG_mask(1, 7)
+ /* Mutually-exclusive page states: { inuse, offlining, offlined, free }. */
+#define PGC_state         PG_mask(3, 9)
+#define PGC_state_inuse   PG_mask(0, 9)
+#define PGC_state_offlining PG_mask(1, 9)
+#define PGC_state_offlined PG_mask(2, 9)
+#define PGC_state_free    PG_mask(3, 9)
+#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == PGC_state_##st)
+
+ /* Count of references to this frame. */
+#define PGC_count_width   PG_shift(9)
+#define PGC_count_mask    ((1UL<<PGC_count_width)-1)
+
+/*
+ * Page needs to be scrubbed. Since this bit can only be set on a page that is
+ * free (i.e. in PGC_state_free) we can reuse PGC_allocated bit.
+ */
+#define _PGC_need_scrub   _PGC_allocated
+#define PGC_need_scrub    PGC_allocated
+
 #ifndef CONFIG_BIGMEM
 /*
  * This definition is solely for the use in struct page_info (and
@@ -82,7 +153,7 @@ struct page_info
             unsigned long type:5;   /* What kind of shadow is this? */
             unsigned long pinned:1; /* Is the shadow pinned? */
             unsigned long head:1;   /* Is this the first page of the shadow? */
-#define PAGE_SH_REFCOUNT_WIDTH 25
+#define PAGE_SH_REFCOUNT_WIDTH (PGT_count_width - 7)
             unsigned long count:PAGE_SH_REFCOUNT_WIDTH; /* Reference count */
         } sh;
 
@@ -198,77 +269,6 @@ struct page_info
 
 #undef __pdx_t
 
-#define PG_shift(idx)   (BITS_PER_LONG - (idx))
-#define PG_mask(x, idx) (x ## UL << PG_shift(idx))
-
- /* The following page types are MUTUALLY EXCLUSIVE. */
-#define PGT_none          PG_mask(0, 3)  /* no special uses of this page   */
-#define PGT_l1_page_table PG_mask(1, 3)  /* using as an L1 page table?     */
-#define PGT_l2_page_table PG_mask(2, 3)  /* using as an L2 page table?     */
-#define PGT_l3_page_table PG_mask(3, 3)  /* using as an L3 page table?     */
-#define PGT_l4_page_table PG_mask(4, 3)  /* using as an L4 page table?     */
-#define PGT_seg_desc_page PG_mask(5, 3)  /* using this page in a GDT/LDT?  */
-#define PGT_shared_page   PG_mask(6, 3)  /* CoW sharable page              */
-#define PGT_writable_page PG_mask(7, 3)  /* has writable mappings?         */
-#define PGT_type_mask     PG_mask(7, 3)  /* Bits 61-63.                    */
-
- /* Page is locked? */
-#define _PGT_locked       PG_shift(4)
-#define PGT_locked        PG_mask(1, 4)
- /* Owning guest has pinned this page to its current type? */
-#define _PGT_pinned       PG_shift(5)
-#define PGT_pinned        PG_mask(1, 5)
- /* Has this page been validated for use as its current type? */
-#define _PGT_validated    PG_shift(6)
-#define PGT_validated     PG_mask(1, 6)
- /* PAE only: is this an L2 page directory containing Xen-private mappings? */
-#define _PGT_pae_xen_l2   PG_shift(7)
-#define PGT_pae_xen_l2    PG_mask(1, 7)
-/* Has this page been *partially* validated for use as its current type? */
-#define _PGT_partial      PG_shift(8)
-#define PGT_partial       PG_mask(1, 8)
-
- /* Count of uses of this frame as its current type. */
-#define PGT_count_width   PG_shift(8)
-#define PGT_count_mask    ((1UL<<PGT_count_width)-1)
-
-/* Are the 'type mask' bits identical? */
-#define PGT_type_equal(x, y) (!(((x) ^ (y)) & PGT_type_mask))
-
- /* Cleared when the owning guest 'frees' this page. */
-#define _PGC_allocated    PG_shift(1)
-#define PGC_allocated     PG_mask(1, 1)
- /* Page is Xen heap? */
-#define _PGC_xen_heap     PG_shift(2)
-#define PGC_xen_heap      PG_mask(1, 2)
- /* Set when is using a page as a page table */
-#define _PGC_page_table   PG_shift(3)
-#define PGC_page_table    PG_mask(1, 3)
- /* 3-bit PAT/PCD/PWT cache-attribute hint. */
-#define PGC_cacheattr_base PG_shift(6)
-#define PGC_cacheattr_mask PG_mask(7, 6)
- /* Page is broken? */
-#define _PGC_broken       PG_shift(7)
-#define PGC_broken        PG_mask(1, 7)
- /* Mutually-exclusive page states: { inuse, offlining, offlined, free }. */
-#define PGC_state         PG_mask(3, 9)
-#define PGC_state_inuse   PG_mask(0, 9)
-#define PGC_state_offlining PG_mask(1, 9)
-#define PGC_state_offlined PG_mask(2, 9)
-#define PGC_state_free    PG_mask(3, 9)
-#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == PGC_state_##st)
-
- /* Count of references to this frame. */
-#define PGC_count_width   PG_shift(9)
-#define PGC_count_mask    ((1UL<<PGC_count_width)-1)
-
-/*
- * Page needs to be scrubbed. Since this bit can only be set on a page that is
- * free (i.e. in PGC_state_free) we can reuse PGC_allocated bit.
- */
-#define _PGC_need_scrub   _PGC_allocated
-#define PGC_need_scrub    PGC_allocated
-
 #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
 #define is_xen_heap_mfn(mfn) \
     (__mfn_valid(mfn) && is_xen_heap_page(__mfn_to_page(mfn)))