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KVM: X86: MMU: no mmu_notifier_seq++ in kvm_age_hva 

The MMU notifier sequence number keeps GPA->HPA mappings in sync when
GPA->HPA lookups are done outside of the MMU lock (e.g., in
tdp_page_fault). Since kvm_age_hva doesn't change GPA->HPA, it's
unnecessary to increment the sequence number.

Signed-off-by: Peter Feiner <pfeiner@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Peter Feiner 2016-09-26 10:45:34 -07:00 committed by Paolo Bonzini
parent c63e45635b
commit 66d73e12f2
1 changed files with 1 additions and 9 deletions
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arch/x86/kvm/mmu.c
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@ -1660,17 +1660,9 @@ int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
* This has some overhead, but not as much as the cost of swapping
* out actively used pages or breaking up actively used hugepages.
*/
if (!shadow_accessed_mask) {
/*
* We are holding the kvm->mmu_lock, and we are blowing up
* shadow PTEs. MMU notifier consumers need to be kept at bay.
* This is correct as long as we don't decouple the mmu_lock
* protected regions (like invalidate_range_start|end does).
*/
kvm->mmu_notifier_seq++;
if (!shadow_accessed_mask)
return kvm_handle_hva_range(kvm, start, end, 0,
kvm_unmap_rmapp);
}
return kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp);
}