[Xen-devel] [RFC PATCH 22/84] x86_64/mm: introduce pl2e in paging_init

[<hongyax@xxxxxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

Introduce pl2e so that we can use l2_ro_mpt to point to the page table
itself.

No functional change.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/x86_64/mm.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 795a467462..ac5e366e5b 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -497,7 +497,7 @@ void __init paging_init(void)
     unsigned long i, mpt_size, va;
     unsigned int n, memflags;
     l3_pgentry_t *l3_ro_mpt;
-    l2_pgentry_t *l2_ro_mpt = NULL;
+    l2_pgentry_t *pl2e = NULL, *l2_ro_mpt;
     struct page_info *l1_pg;
 
     /*
@@ -547,7 +547,7 @@ void __init paging_init(void)
             (L2_PAGETABLE_SHIFT - 3 + PAGE_SHIFT)));
 
         if ( cpu_has_page1gb &&
-             !((unsigned long)l2_ro_mpt & ~PAGE_MASK) &&
+             !((unsigned long)pl2e & ~PAGE_MASK) &&
              (mpt_size >> L3_PAGETABLE_SHIFT) > (i >> PAGETABLE_ORDER) )
         {
             unsigned int k, holes;
@@ -607,7 +607,7 @@ void __init paging_init(void)
             memset((void *)(RDWR_MPT_VIRT_START + (i << L2_PAGETABLE_SHIFT)),
                    0xFF, 1UL << L2_PAGETABLE_SHIFT);
         }
-        if ( !((unsigned long)l2_ro_mpt & ~PAGE_MASK) )
+        if ( !((unsigned long)pl2e & ~PAGE_MASK) )
         {
             if ( (l2_ro_mpt = alloc_xen_pagetable()) == NULL )
                 goto nomem;
@@ -615,13 +615,14 @@ void __init paging_init(void)
             l3e_write(&l3_ro_mpt[l3_table_offset(va)],
                       l3e_from_paddr(__pa(l2_ro_mpt),
                                      __PAGE_HYPERVISOR_RO | _PAGE_USER));
+            pl2e = l2_ro_mpt;
             ASSERT(!l2_table_offset(va));
         }
         /* NB. Cannot be GLOBAL: guest user mode should not see it. */
         if ( l1_pg )
-            l2e_write(l2_ro_mpt, l2e_from_page(
+            l2e_write(pl2e, l2e_from_page(
                 l1_pg, /*_PAGE_GLOBAL|*/_PAGE_PSE|_PAGE_USER|_PAGE_PRESENT));
-        l2_ro_mpt++;
+        pl2e++;
     }
 #undef CNT
 #undef MFN
@@ -637,7 +638,8 @@ void __init paging_init(void)
     clear_page(l2_ro_mpt);
     l3e_write(&l3_ro_mpt[l3_table_offset(HIRO_COMPAT_MPT_VIRT_START)],
               l3e_from_paddr(__pa(l2_ro_mpt), __PAGE_HYPERVISOR_RO));
-    l2_ro_mpt += l2_table_offset(HIRO_COMPAT_MPT_VIRT_START);
+    pl2e = l2_ro_mpt;
+    pl2e += l2_table_offset(HIRO_COMPAT_MPT_VIRT_START);
     /* Allocate and map the compatibility mode machine-to-phys table. */
     mpt_size = (mpt_size >> 1) + (1UL << (L2_PAGETABLE_SHIFT - 1));
     if ( mpt_size > RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START )
@@ -650,7 +652,7 @@ void __init paging_init(void)
              sizeof(*compat_machine_to_phys_mapping))
     BUILD_BUG_ON((sizeof(*frame_table) & ~sizeof(*frame_table)) % \
                  sizeof(*compat_machine_to_phys_mapping));
-    for ( i = 0; i < (mpt_size >> L2_PAGETABLE_SHIFT); i++, l2_ro_mpt++ )
+    for ( i = 0; i < (mpt_size >> L2_PAGETABLE_SHIFT); i++, pl2e++ )
     {
         memflags = MEMF_node(phys_to_nid(i <<
             (L2_PAGETABLE_SHIFT - 2 + PAGE_SHIFT)));
@@ -672,7 +674,7 @@ void __init paging_init(void)
                         (i << L2_PAGETABLE_SHIFT)),
                0xFF, 1UL << L2_PAGETABLE_SHIFT);
         /* NB. Cannot be GLOBAL as the ptes get copied into per-VM space. */
-        l2e_write(l2_ro_mpt, l2e_from_page(l1_pg, _PAGE_PSE|_PAGE_PRESENT));
+        l2e_write(pl2e, l2e_from_page(l1_pg, _PAGE_PSE|_PAGE_PRESENT));
     }
 #undef CNT
 #undef MFN
-- 
2.17.1


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