[Xen-changelog] [xen stable-4.10] x86/paging: don't unconditionally BUG() on finding SHARED_M2P_ENTRY

[patchbot@xxxxxxx]

commit e62b9fe7bccbe8acd635c18deabe2a5f43a8cd4e
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 8 15:27:14 2017 +0000
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Fri Dec 8 15:27:14 2017 +0000

    x86/paging: don't unconditionally BUG() on finding SHARED_M2P_ENTRY
    
    PV guests can fully control the values written into the P2M.
    
    This is XSA-251.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/mm/paging.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index 1e2c9ba..755a8f8 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -274,7 +274,7 @@ void paging_mark_pfn_dirty(struct domain *d, pfn_t pfn)
         return;
 
     /* Shared MFNs should NEVER be marked dirty */
-    BUG_ON(SHARED_M2P(pfn_x(pfn)));
+    BUG_ON(paging_mode_translate(d) && SHARED_M2P(pfn_x(pfn)));
 
     /*
      * Values with the MSB set denote MFNs that aren't really part of the
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.10

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