[xen master] x86: don't ignore foreigndom on L2/L3/L4 page table updates

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[xen master] x86: don't ignore foreigndom on L2/L3/L4 page table updates

patchbot
commit 7993e3be68558097050bc7495d3b4a00287841e1
Author:     Jan Beulich <[hidden email]>
AuthorDate: Tue Dec 5 17:23:53 2017 +0100
Commit:     Jan Beulich <[hidden email]>
CommitDate: Tue Dec 5 17:23:53 2017 +0100

    x86: don't ignore foreigndom on L2/L3/L4 page table updates
   
    Silently assuming DOMID_SELF is unlikely to be a good idea for page
    table updates. For PGT_writable pages, though, it seems better to allow
    the writes, so the same check isn't being applied there.
   
    Also add blank lines between the individual case blocks.
   
    Signed-off-by: Jan Beulich <[hidden email]>
    Acked-by: Andrew Cooper <[hidden email]>
---
 xen/arch/x86/mm.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 3c84ae8..e919956 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3662,18 +3662,28 @@ long do_mmu_update(
                                       cmd == MMU_PT_UPDATE_PRESERVE_AD, v,
                                       pg_owner);
                     break;
+
                 case PGT_l2_page_table:
+                    if ( unlikely(pg_owner != pt_owner) )
+                        break;
                     rc = mod_l2_entry(va, l2e_from_intpte(req.val), mfn,
                                       cmd == MMU_PT_UPDATE_PRESERVE_AD, v);
                     break;
+
                 case PGT_l3_page_table:
+                    if ( unlikely(pg_owner != pt_owner) )
+                        break;
                     rc = mod_l3_entry(va, l3e_from_intpte(req.val), mfn,
                                       cmd == MMU_PT_UPDATE_PRESERVE_AD, v);
                     break;
+
                 case PGT_l4_page_table:
+                    if ( unlikely(pg_owner != pt_owner) )
+                        break;
                     rc = mod_l4_entry(va, l4e_from_intpte(req.val), mfn,
                                       cmd == MMU_PT_UPDATE_PRESERVE_AD, v);
                     break;
+
                 case PGT_writable_page:
                     perfc_incr(writable_mmu_updates);
                     if ( paging_write_guest_entry(v, va, req.val, _mfn(mfn)) )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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