[Xen-changelog] [xen master] x86/mm/shadow: remove dead code for avoiding Xen entries on 32-bit tables.

[patchbot@xxxxxxx]

commit 078654af2de6733fb5b3da1e07c1962832e998c1
Author:     Tim Deegan <tim@xxxxxxx>
AuthorDate: Thu May 2 11:37:56 2013 +0100
Commit:     Tim Deegan <tim@xxxxxxx>
CommitDate: Thu May 9 13:00:26 2013 +0100

    x86/mm/shadow: remove dead code for avoiding Xen entries on 32-bit tables.
    
    All non-external-mode (==PV) guests have 4-level pagetables now that
    the PAE build of Xen is gone.
    
    This patch should have no effect, since the condition it removes could
    never be true anyway: the l2 offset of HYPERVISOR_VIRT_START on 64-bit
    Xen is much higher than any l2 offset we could have seen in the
    tables (and indeed bigger than the 'int' type, which clang was
    complaining about).  Actual compat PV guest xen entries are handled by
    the equivalent test in the 64-bit SHADOW_FOREACH_L2E() below.
    
    Reported-by: Julien Grall <julien.grall@xxxxxxxxxx>
    Signed-off-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c |   49 +++++++++++++++++----------------------
 1 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index a8ef75e..e216063 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -1305,26 +1305,23 @@ do {                                                    
                \
 
 #if GUEST_PAGING_LEVELS == 2
 
-/* 32-bit l2 on PAE/64: four pages, touch every second entry, and avoid Xen */
+/* 32-bit l2 on PAE/64: four pages, touch every second entry */
 #define SHADOW_FOREACH_L2E(_sl2mfn, _sl2e, _gl2p, _done, _dom, _code)     \
 do {                                                                      \
     int _i, _j, __done = 0;                                               \
-    int _xen = !shadow_mode_external(_dom);                               \
-    ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_32_shadow);\
+    ASSERT(shadow_mode_external(_dom));                                   \
+    ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_32_shadow);      \
     for ( _j = 0; _j < 4 && !__done; _j++ )                               \
     {                                                                     \
         shadow_l2e_t *_sp = sh_map_domain_page(_sl2mfn);                  \
         for ( _i = 0; _i < SHADOW_L2_PAGETABLE_ENTRIES; _i += 2 )         \
-            if ( (!(_xen))                                                \
-                 || ((_j * SHADOW_L2_PAGETABLE_ENTRIES) + _i)             \
-                 < (HYPERVISOR_VIRT_START >> SHADOW_L2_PAGETABLE_SHIFT) ) \
-            {                                                             \
-                (_sl2e) = _sp + _i;                                       \
-                if ( shadow_l2e_get_flags(*(_sl2e)) & _PAGE_PRESENT )     \
-                    {_code}                                               \
-                if ( (__done = (_done)) ) break;                          \
-                increment_ptr_to_guest_entry(_gl2p);                      \
-            }                                                             \
+        {                                                                 \
+            (_sl2e) = _sp + _i;                                           \
+            if ( shadow_l2e_get_flags(*(_sl2e)) & _PAGE_PRESENT )         \
+                {_code}                                                   \
+            if ( (__done = (_done)) ) break;                              \
+            increment_ptr_to_guest_entry(_gl2p);                          \
+        }                                                                 \
         sh_unmap_domain_page(_sp);                                        \
         if ( _j < 3 ) _sl2mfn = sh_next_page(_sl2mfn);                    \
     }                                                                     \
@@ -1332,26 +1329,22 @@ do {                                                    
                  \
 
 #elif GUEST_PAGING_LEVELS == 3
 
-/* PAE: if it's an l2h, don't touch Xen mappings */
+/* PAE: touch all entries */
 #define SHADOW_FOREACH_L2E(_sl2mfn, _sl2e, _gl2p, _done, _dom, _code)      \
 do {                                                                       \
     int _i;                                                                \
-    int _xen = !shadow_mode_external(_dom);                                \
     shadow_l2e_t *_sp = sh_map_domain_page((_sl2mfn));                     \
-    ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_pae_shadow \
-           || mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2h_pae_shadow);\
+    ASSERT(shadow_mode_external(_dom));                                    \
+    ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_pae_shadow        \
+           || mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2h_pae_shadow);  \
     for ( _i = 0; _i < SHADOW_L2_PAGETABLE_ENTRIES; _i++ )                 \
-        if ( (!(_xen))                                                     \
-             || mfn_to_page(_sl2mfn)->u.sh.type != SH_type_l2h_pae_shadow\
-             || ((_i + (3 * SHADOW_L2_PAGETABLE_ENTRIES))                  \
-                 < (HYPERVISOR_VIRT_START >> SHADOW_L2_PAGETABLE_SHIFT)) ) \
-        {                                                                  \
-            (_sl2e) = _sp + _i;                                            \
-            if ( shadow_l2e_get_flags(*(_sl2e)) & _PAGE_PRESENT )          \
-                {_code}                                                    \
-            if ( _done ) break;                                            \
-            increment_ptr_to_guest_entry(_gl2p);                           \
-        }                                                                  \
+    {                                                                      \
+        (_sl2e) = _sp + _i;                                                \
+        if ( shadow_l2e_get_flags(*(_sl2e)) & _PAGE_PRESENT )              \
+            {_code}                                                        \
+        if ( _done ) break;                                                \
+        increment_ptr_to_guest_entry(_gl2p);                               \
+    }                                                                      \
     sh_unmap_domain_page(_sp);                                             \
 } while (0)
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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