[Xen-changelog] [xen master] x86/NPT: don't walk entire page tables when globally changing types

[patchbot@xxxxxxx]

commit 9e52ad4f4d0d8051c9dd45a8b662cd1943ee486f
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 2 11:53:38 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 2 11:53:38 2014 +0200

    x86/NPT: don't walk entire page tables when globally changing types
    
    Instead leverage the NPF VM exit enforcement by marking just the top
    level entries as needing recalculation of their type, building on the
    respective range type change modifications.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/p2m-ept.c |    4 +-
 xen/arch/x86/mm/p2m-pt.c  |  116 +++++++--------------------------------------
 xen/arch/x86/mm/p2m.c     |    4 ++
 3 files changed, 22 insertions(+), 102 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 86c06e8..bb98945 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -890,11 +890,9 @@ static void ept_change_entry_type_global(struct p2m_domain 
*p2m,
 {
     unsigned long mfn = ept_get_asr(&p2m->ept);
 
-    if ( !mfn || ot == nt )
+    if ( !mfn )
         return;
 
-    BUG_ON(!p2m_is_changeable(ot) || !p2m_is_changeable(nt));
-
     if ( ept_invalidate_emt(_mfn(mfn), 1) )
         ept_sync_domain(p2m);
 }
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 4d3ce1f..2cbb126 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -828,118 +828,36 @@ pod_retry_l1:
     return (p2m_is_valid(*t) || p2m_is_grant(*t)) ? mfn : _mfn(INVALID_MFN);
 }
 
-/* Walk the whole p2m table, changing any entries of the old type
- * to the new type.  This is used in hardware-assisted paging to 
- * quickly enable or diable log-dirty tracking */
 static void p2m_pt_change_entry_type_global(struct p2m_domain *p2m,
                                             p2m_type_t ot, p2m_type_t nt)
 {
-    unsigned long mfn, gfn, flags;
-    l1_pgentry_t l1e_content;
-    l1_pgentry_t *l1e;
-    l2_pgentry_t *l2e;
-    mfn_t l1mfn, l2mfn, l3mfn;
-    unsigned long i1, i2, i3;
-    l3_pgentry_t *l3e;
-    l4_pgentry_t *l4e;
-    unsigned long i4;
-
-    BUG_ON(p2m_is_grant(ot) || p2m_is_grant(nt));
-    BUG_ON(ot != nt && (ot == p2m_mmio_direct || nt == p2m_mmio_direct));
-
-    if ( !paging_mode_translate(p2m->domain) )
-        return;
+    l1_pgentry_t *tab;
+    unsigned long gfn = 0;
+    unsigned int i, changed;
 
     if ( pagetable_get_pfn(p2m_get_pagetable(p2m)) == 0 )
         return;
 
-    ASSERT(p2m_locked_by_me(p2m));
-
-    l4e = map_domain_page(mfn_x(pagetable_get_mfn(p2m_get_pagetable(p2m))));
+    ASSERT(hap_enabled(p2m->domain));
 
-    for ( i4 = 0; i4 < L4_PAGETABLE_ENTRIES; i4++ )
+    tab = map_domain_page(mfn_x(pagetable_get_mfn(p2m_get_pagetable(p2m))));
+    for ( changed = i = 0; i < (1 << PAGETABLE_ORDER); ++i )
     {
-        if ( !(l4e_get_flags(l4e[i4]) & _PAGE_PRESENT) )
-        {
-            continue;
-        }
-        l3mfn = _mfn(l4e_get_pfn(l4e[i4]));
-        l3e = map_domain_page(l4e_get_pfn(l4e[i4]));
-        for ( i3 = 0;
-              i3 < L3_PAGETABLE_ENTRIES;
-              i3++ )
-        {
-            if ( !(l3e_get_flags(l3e[i3]) & _PAGE_PRESENT) )
-            {
-                continue;
-            }
-            if ( (l3e_get_flags(l3e[i3]) & _PAGE_PSE) )
-            {
-                flags = l3e_get_flags(l3e[i3]);
-                if ( p2m_flags_to_type(flags) != ot )
-                    continue;
-                mfn = l3e_get_pfn(l3e[i3]);
-                gfn = get_gpfn_from_mfn(mfn);
-                flags = p2m_type_to_flags(nt, _mfn(mfn));
-                l1e_content = l1e_from_pfn(mfn, flags | _PAGE_PSE);
-                p2m->write_p2m_entry(p2m, gfn,
-                                     (l1_pgentry_t *)&l3e[i3],
-                                     l1e_content, 3);
-                continue;
-            }
+        l1_pgentry_t e = tab[i];
 
-            l2mfn = _mfn(l3e_get_pfn(l3e[i3]));
-            l2e = map_domain_page(l3e_get_pfn(l3e[i3]));
-            for ( i2 = 0; i2 < L2_PAGETABLE_ENTRIES; i2++ )
-            {
-                if ( !(l2e_get_flags(l2e[i2]) & _PAGE_PRESENT) )
-                {
-                    continue;
-                }
-
-                if ( (l2e_get_flags(l2e[i2]) & _PAGE_PSE) )
-                {
-                    flags = l2e_get_flags(l2e[i2]);
-                    if ( p2m_flags_to_type(flags) != ot )
-                        continue;
-                    mfn = l2e_get_pfn(l2e[i2]);
-                    /* Do not use get_gpfn_from_mfn because it may return 
-                       SHARED_M2P_ENTRY */
-                    gfn = (i2 + (i3 + (i4 * L3_PAGETABLE_ENTRIES))
-                           * L2_PAGETABLE_ENTRIES) * L1_PAGETABLE_ENTRIES; 
-                    flags = p2m_type_to_flags(nt, _mfn(mfn));
-                    l1e_content = l1e_from_pfn(mfn, flags | _PAGE_PSE);
-                    p2m->write_p2m_entry(p2m, gfn,
-                                         (l1_pgentry_t *)&l2e[i2],
-                                         l1e_content, 2);
-                    continue;
-                }
-
-                l1mfn = _mfn(l2e_get_pfn(l2e[i2]));
-                l1e = map_domain_page(mfn_x(l1mfn));
-
-                for ( i1 = 0; i1 < L1_PAGETABLE_ENTRIES; i1++ )
-                {
-                    flags = l1e_get_flags(l1e[i1]);
-                    if ( p2m_flags_to_type(flags) != ot )
-                        continue;
-                    mfn = l1e_get_pfn(l1e[i1]);
-                    gfn = i1 + (i2 + (i3 + (i4 * L3_PAGETABLE_ENTRIES))
-                                * L2_PAGETABLE_ENTRIES) * 
L1_PAGETABLE_ENTRIES; 
-                    /* create a new 1le entry with the new type */
-                    flags = p2m_type_to_flags(nt, _mfn(mfn));
-                    l1e_content = p2m_l1e_from_pfn(mfn, flags);
-                    p2m->write_p2m_entry(p2m, gfn, &l1e[i1],
-                                         l1e_content, 1);
-                }
-                unmap_domain_page(l1e);
-            }
-            unmap_domain_page(l2e);
+        if ( (l1e_get_flags(e) & _PAGE_PRESENT) &&
+             !needs_recalc(l1, e) )
+        {
+            set_recalc(l1, e);
+            p2m->write_p2m_entry(p2m, gfn, &tab[i], e, 4);
+            ++changed;
         }
-        unmap_domain_page(l3e);
+        gfn += 1UL << (L4_PAGETABLE_SHIFT - PAGE_SHIFT);
     }
+    unmap_domain_page(tab);
 
-    unmap_domain_page(l4e);
+    if ( changed )
+         flush_tlb_mask(p2m->domain->domain_dirty_cpumask);
 }
 
 static int p2m_pt_change_entry_type_range(struct p2m_domain *p2m,
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index afcea76..03e9ad5 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -214,6 +214,10 @@ void p2m_change_entry_type_global(struct domain *d,
                                   p2m_type_t ot, p2m_type_t nt)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    ASSERT(ot != nt);
+    ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
+
     p2m_lock(p2m);
     p2m->change_entry_type_global(p2m, ot, nt);
     p2m->global_logdirty = (nt == p2m_ram_logdirty);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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