[Xen-changelog] [xen master] x86/mem_sharing: Skip xen heap pages in memshr nominate

[patchbot@xxxxxxx]

commit 67de3c5df067c6fcdc7c452752c1a14863d9b1c8
Author:     Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
AuthorDate: Fri Jan 24 10:28:56 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jan 24 10:28:56 2020 +0100

    x86/mem_sharing: Skip xen heap pages in memshr nominate
    
    Trying to share these would fail anyway, better to skip them early.
    
    Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/mm/mem_sharing.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index c39e56f5b9..5ce075d307 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -840,6 +840,11 @@ static int nominate_page(struct domain *d, gfn_t gfn,
     if ( !p2m_is_sharable(p2mt) )
         goto out;
 
+    /* Skip xen heap pages */
+    page = mfn_to_page(mfn);
+    if ( !page || is_xen_heap_page(page) )
+        goto out;
+
     /* Check if there are mem_access/remapped altp2m entries for this page */
     if ( altp2m_active(d) )
     {
@@ -870,7 +875,6 @@ static int nominate_page(struct domain *d, gfn_t gfn,
     }
 
     /* Try to convert the mfn to the sharable type */
-    page = mfn_to_page(mfn);
     ret = page_make_sharable(d, page, expected_refcnt);
     if ( ret )
         goto out;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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