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KVM: x86: MMU: Consolidate BUG_ON checks for reverse-mapped sptes

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At some call sites of rmap_get_first() and rmap_get_next(), BUG_ON is
placed right after the call to detect unrelated sptes which must not be
found in the reverse-mapping list.

Move this check in rmap_get_first/next() so that all call sites, not
just the users of the for_each_rmap_spte() macro, will be checked the
same way.

One thing to keep in mind is that kvm_mmu_unlink_parents() also uses
rmap_get_first() to handle parent sptes.  The change will not break it
because parent sptes are present, at least until drop_parent_pte()
actually unlinks them, and not mmio-sptes.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Takuya Yoshikawa
2015-11-20 17:45:44 +09:00
committed by Paolo Bonzini
parent afd28fe1c9
commit 77fbbbd2f0
2 changed files with 19 additions and 11 deletions
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4
Documentation/virtual/kvm/mmu.txt
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@@ -203,10 +203,10 @@ Shadow pages contain the following information:
page cannot be destroyed. See role.invalid.
parent_ptes:
The reverse mapping for the pte/ptes pointing at this page's spt. If
parent_ptes bit 0 is zero, only one spte points at this pages and
parent_ptes bit 0 is zero, only one spte points at this page and
parent_ptes points at this single spte, otherwise, there exists multiple
sptes pointing at this page and (parent_ptes & ~0x1) points at a data
structure with a list of parent_ptes.
structure with a list of parent sptes.
unsync:
If true, then the translations in this page may not match the guest's
translation. This is equivalent to the state of the tlb when a pte is