[PATCH 2/5] x86/mm: rename PGC_page_table to PGC_shadowed_pt

[Jan Beulich <jbeulich@xxxxxxxx>]

The original name didn't express the purpose of the flag: It is being
set once a page table page obtains a shadow, and it is removed when the
last shadow of a page was destroyed.

In set_tlbflush_timestamp() also remove the 2nd half of the condition as
being redundant (PGC_shadowed_pt can't be set on a page without shadow
mode being enabled on the owning domain).

Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/include/asm/mm.h
+++ b/xen/arch/x86/include/asm/mm.h
@@ -70,9 +70,9 @@
  /* 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)
+ /* Set when a page table page has been shadowed. */
+#define _PGC_shadowed_pt  PG_shift(3)
+#define PGC_shadowed_pt   PG_mask(1, 3)
  /* Page is broken? */
 #define _PGC_broken       PG_shift(4)
 #define PGC_broken        PG_mask(1, 4)
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -803,7 +803,7 @@ p2m_pod_zero_check_superpage(struct p2m_
         for ( k = 0, page = mfn_to_page(mfn); k < n; ++k, ++page )
             if ( is_special_page(page) ||
                  !(page->count_info & PGC_allocated) ||
-                 (page->count_info & PGC_page_table) ||
+                 (page->count_info & PGC_shadowed_pt) ||
                  (page->count_info & PGC_count_mask) > max_ref )
                 goto out;
     }
@@ -946,7 +946,7 @@ p2m_pod_zero_check(struct p2m_domain *p2
 
             if ( !is_special_page(pg) &&
                  (pg->count_info & PGC_allocated) &&
-                 !(pg->count_info & PGC_page_table) &&
+                 !(pg->count_info & PGC_shadowed_pt) &&
                  ((pg->count_info & PGC_count_mask) <= max_ref) )
                 map[i] = map_domain_page(mfns[i]);
         }
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -185,7 +185,7 @@ static void sh_oos_audit(struct domain *
                 BUG();
             }
             pg = mfn_to_page(oos[idx]);
-            if ( !(pg->count_info & PGC_page_table) )
+            if ( !(pg->count_info & PGC_shadowed_pt) )
             {
                 printk("%s: idx %x gmfn %lx not a pt (count %lx)\n",
                        __func__, idx, mfn_x(oos[idx]), pg->count_info);
@@ -716,7 +716,7 @@ void shadow_promote(struct domain *d, mf
            || d->is_shutting_down);
 
     /* Is the page already shadowed? */
-    if ( !test_and_set_bit(_PGC_page_table, &page->count_info) )
+    if ( !test_and_set_bit(_PGC_shadowed_pt, &page->count_info) )
     {
         page->shadow_flags = 0;
 #ifdef CONFIG_HVM
@@ -734,7 +734,7 @@ void shadow_demote(struct domain *d, mfn
 {
     struct page_info *page = mfn_to_page(gmfn);
 
-    ASSERT(test_bit(_PGC_page_table, &page->count_info));
+    ASSERT(test_bit(_PGC_shadowed_pt, &page->count_info));
     ASSERT(page->shadow_flags & (1u << type));
 
     page->shadow_flags &= ~(1u << type);
@@ -748,7 +748,7 @@ void shadow_demote(struct domain *d, mfn
             oos_hash_remove(d, gmfn);
         }
 #endif
-        clear_bit(_PGC_page_table, &page->count_info);
+        clear_bit(_PGC_shadowed_pt, &page->count_info);
     }
 
     TRACE_SHADOW_PATH_FLAG(TRCE_SFLAG_DEMOTE);
@@ -779,7 +779,7 @@ sh_validate_guest_entry(struct vcpu *v,
     // Ditto for L2s before L3s, etc.
     //
 
-    if ( !(page->count_info & PGC_page_table) )
+    if ( !(page->count_info & PGC_shadowed_pt) )
         return 0;  /* Not shadowed at all */
 
     if ( page->shadow_flags & SHF_L1_32 )
@@ -2266,7 +2266,7 @@ void sh_remove_shadows(struct domain *d,
     SHADOW_PRINTK("d%d gmfn=%"PRI_mfn"\n", d->domain_id, mfn_x(gmfn));
 
     /* Bail out now if the page is not shadowed */
-    if ( (pg->count_info & PGC_page_table) == 0 )
+    if ( !(pg->count_info & PGC_shadowed_pt) )
     {
         paging_unlock(d);
         return;
@@ -2283,7 +2283,7 @@ void sh_remove_shadows(struct domain *d,
      */
 #define DO_UNSHADOW(_type) do {                                         \
     t = (_type);                                                        \
-    if ( !(pg->count_info & PGC_page_table) ||                          \
+    if ( !(pg->count_info & PGC_shadowed_pt) ||                         \
          !(pg->shadow_flags & (1 << t)) )                               \
         break;                                                          \
     smfn = shadow_hash_lookup(d, mfn_x(gmfn), t);                       \
@@ -2299,7 +2299,7 @@ void sh_remove_shadows(struct domain *d,
     else if ( sh_type_has_up_pointer(d, t) )                            \
         sh_remove_shadow_via_pointer(d, smfn);                          \
     if ( !fast &&                                                       \
-         (pg->count_info & PGC_page_table) &&                           \
+         (pg->count_info & PGC_shadowed_pt) &&                          \
          (pg->shadow_flags & (1 << t)) )                                \
     {                                                                   \
         HASH_CALLBACKS_CHECK(SHF_page_type_mask);                       \
@@ -2322,7 +2322,7 @@ void sh_remove_shadows(struct domain *d,
 #undef DO_UNSHADOW
 
     /* If that didn't catch the shadows, something is wrong */
-    if ( !fast && all && (pg->count_info & PGC_page_table) )
+    if ( !fast && all && (pg->count_info & PGC_shadowed_pt) )
     {
         printk(XENLOG_G_ERR "can't find all shadows of mfn %"PRI_mfn
                " (shadow_flags=%04x)\n", mfn_x(gmfn), pg->shadow_flags);
@@ -2339,7 +2339,7 @@ void sh_remove_shadows(struct domain *d,
 void shadow_prepare_page_type_change(struct domain *d,
                                      const struct page_info *page)
 {
-    if ( !(page->count_info & PGC_page_table) )
+    if ( !(page->count_info & PGC_shadowed_pt) )
         return;
 
 #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -320,7 +320,7 @@ static inline void sh_terminate_list(str
 static inline int sh_page_has_multiple_shadows(struct page_info *pg)
 {
     u32 shadows;
-    if ( !(pg->count_info & PGC_page_table) )
+    if ( !(pg->count_info & PGC_shadowed_pt) )
         return 0;
     shadows = pg->shadow_flags & SHF_page_type_mask;
     /* More than one type bit set in shadow-flags? */
@@ -332,7 +332,7 @@ static inline int sh_page_has_multiple_s
  * domain is translated, &c */
 static inline int page_is_out_of_sync(struct page_info *p)
 {
-    return (p->count_info & PGC_page_table)
+    return (p->count_info & PGC_shadowed_pt)
         && (p->shadow_flags & SHF_out_of_sync);
 }
 
@@ -343,7 +343,7 @@ static inline int mfn_is_out_of_sync(mfn
 
 static inline int page_oos_may_write(struct page_info *p)
 {
-    return (p->count_info & PGC_page_table)
+    return (p->count_info & PGC_shadowed_pt)
         && (p->shadow_flags & SHF_oos_may_write);
 }
 
@@ -545,7 +545,7 @@ sh_mfn_is_a_page_table(mfn_t gmfn)
 
     owner = page_get_owner(page);
     if ( owner && shadow_mode_refcounts(owner)
-         && (page->count_info & PGC_page_table) )
+         && (page->count_info & PGC_shadowed_pt) )
         return 1;
 
     type_info = page->u.inuse.type_info & PGT_type_mask;
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -593,8 +593,7 @@ static inline void set_tlbflush_timestam
      *  2. Shadow mode reuses this field for shadowed page tables to store
      *     flags info -- we don't want to conflict with that.
      */
-    if ( !(page->count_info & PGC_page_table) ||
-         !shadow_mode_enabled(page_get_owner(page)) )
+    if ( !(page->count_info & PGC_shadowed_pt) )
         page_set_tlbflush_timestamp(page);
 }