[Xen-changelog] [xen master] x86/mm: fix incorrect unmapping of 2MB and 1GB pages

[patchbot@xxxxxxx]

commit efa9596e9d167c8fb7d1c4446c10f7ca30453646
Author:     Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
AuthorDate: Wed May 17 17:23:15 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed May 17 17:23:15 2017 +0200

    x86/mm: fix incorrect unmapping of 2MB and 1GB pages
    
    The same set of functions is used to set as well as to clean
    P2M entries, except that for clean operations INVALID_MFN (~0UL)
    is passed as a parameter. Unfortunately, when calculating an
    appropriate target order for a particular mapping INVALID_MFN
    is not taken into account which leads to 4K page target order
    being set each time even for 2MB and 1GB mappings. This eventually
    breaks down an EPT structure irreversibly into 4K mappings which
    prevents consecutive high order mappings to this area.
    
    Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Release-acked-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/x86/mm/p2m-ept.c |  3 ++-
 xen/arch/x86/mm/p2m.c     | 11 +++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index f37a1f2..f98121d 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -681,6 +681,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, 
mfn_t mfn,
     ept_entry_t *table, *ept_entry = NULL;
     unsigned long gfn_remainder = gfn;
     unsigned int i, target = order / EPT_TABLE_ORDER;
+    unsigned long fn_mask = !mfn_eq(mfn, INVALID_MFN) ? (gfn | mfn_x(mfn)) : 
gfn;
     int ret, rc = 0;
     bool_t entry_written = 0;
     bool_t direct_mmio = (p2mt == p2m_mmio_direct);
@@ -701,7 +702,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, 
mfn_t mfn,
      * 2. gfn not exceeding guest physical address width.
      * 3. passing a valid order.
      */
-    if ( ((gfn | mfn_x(mfn)) & ((1UL << order) - 1)) ||
+    if ( (fn_mask & ((1UL << order) - 1)) ||
          ((u64)gfn >> ((ept->wl + 1) * EPT_TABLE_ORDER)) ||
          (order % EPT_TABLE_ORDER) )
         return -EINVAL;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index dacf3e2..c6ec1a4 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -559,12 +559,15 @@ int p2m_set_entry(struct p2m_domain *p2m, unsigned long 
gfn, mfn_t mfn,
     while ( todo )
     {
         if ( hap_enabled(d) )
-            order = (!((gfn | mfn_x(mfn) | todo) &
-                       ((1ul << PAGE_ORDER_1G) - 1)) &&
+        {
+            unsigned long fn_mask = !mfn_eq(mfn, INVALID_MFN) ?
+                                     (gfn | mfn_x(mfn) | todo) : (gfn | todo);
+
+            order = (!(fn_mask & ((1ul << PAGE_ORDER_1G) - 1)) &&
                      hap_has_1gb) ? PAGE_ORDER_1G :
-                    (!((gfn | mfn_x(mfn) | todo) &
-                       ((1ul << PAGE_ORDER_2M) - 1)) &&
+                    (!(fn_mask & ((1ul << PAGE_ORDER_2M) - 1)) &&
                      hap_has_2mb) ? PAGE_ORDER_2M : PAGE_ORDER_4K;
+        }
         else
             order = 0;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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