diff options
| author | Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> | 2012-07-17 21:52:52 +0800 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-07-19 21:09:10 -0300 |
| commit | 86fde74cf5b829627b37ca86322acfdd99b524b8 (patch) | |
| tree | 0a30f492d7326f8fcb0fbb17c530e57166ab6d29 | |
| parent | 9d3c92af47d853d4e31ee971dba7bc086275b7b3 (diff) | |
KVM: MMU: track the refcount when unmap the page
It will trigger a WARN_ON if the page has been freed but it is still
used in mmu, it can help us to detect mm bug early
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index a5d6ef785b7e..685a48557389 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -556,6 +556,14 @@ static int mmu_spte_clear_track_bits(u64 *sptep) return 0; pfn = spte_to_pfn(old_spte); + + /* + * KVM does not hold the refcount of the page used by + * kvm mmu, before reclaiming the page, we should + * unmap it from mmu first. + */ + WARN_ON(!kvm_is_mmio_pfn(pfn) && !page_count(pfn_to_page(pfn))); + if (!shadow_accessed_mask || old_spte & shadow_accessed_mask) kvm_set_pfn_accessed(pfn); if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask)) |