[Xen-changelog] [xen master] x86/shadow: Fix #PFs from emulated writes crossing a page boundary

[patchbot@xxxxxxx]

commit f600fa5345d008ec686bfe2c579bbb37b11c7972
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Nov 25 17:23:04 2016 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Dec 2 17:23:01 2016 +0000

    x86/shadow: Fix #PFs from emulated writes crossing a page boundary
    
    When translating the second frame of a write crossing a page boundary, mask
    the linear address down to the page boundary.
    
    This causes the correct %cr2 being reported to the guest in the case that 
the
    second frame suffers a pagefault during translation.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/mm/shadow/common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 9f3bed9..1623a07 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1802,7 +1802,8 @@ void *sh_emulate_map_dest(struct vcpu *v, unsigned long 
vaddr,
     else
     {
         /* This write crosses a page boundary. Translate the second page. */
-        sh_ctxt->mfn[1] = emulate_gva_to_mfn(v, vaddr + bytes - 1, sh_ctxt);
+        sh_ctxt->mfn[1] = emulate_gva_to_mfn(
+            v, (vaddr + bytes - 1) & PAGE_MASK, sh_ctxt);
         if ( !mfn_valid(sh_ctxt->mfn[1]) )
             return ((mfn_x(sh_ctxt->mfn[1]) == BAD_GVA_TO_GFN) ?
                     MAPPING_EXCEPTION :
--
generated by git-patchbot for /home/xen/git/xen.git#master

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