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| author | Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> | 2013-01-08 19:43:28 +0900 |
|---|---|---|
| committer | Gleb Natapov <gleb@redhat.com> | 2013-01-14 11:13:15 +0200 |
| commit | c972f3b125d8818748429b94cd2e59f473943a33 (patch) | |
| tree | da8ecba2b20a5804fa193471a980e301f6b8b265 | |
| parent | aa11e3a8a6d9f92c3fe4b91a9aca5d8c23d55d4d (diff) | |
| download | linux-stable-c972f3b125d8818748429b94cd2e59f473943a33.tar.gz linux-stable-c972f3b125d8818748429b94cd2e59f473943a33.tar.bz2 linux-stable-c972f3b125d8818748429b94cd2e59f473943a33.zip | |
KVM: Write protect the updated slot only when dirty logging is enabled
Calling kvm_mmu_slot_remove_write_access() for a deleted slot does
nothing but search for non-existent mmu pages which have mappings to
that deleted memory; this is safe but a waste of time.
Since we want to make the function rmap based in a later patch, in a
manner which makes it unsafe to be called for a deleted slot, we makes
the caller see if the slot is non-zero and being dirty logged.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 8 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 1 |
2 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1c9c834b72f0..add5e4801968 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6897,7 +6897,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, spin_lock(&kvm->mmu_lock); if (nr_mmu_pages) kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); - kvm_mmu_slot_remove_write_access(kvm, mem->slot); + /* + * Write protect all pages for dirty logging. + * Existing largepage mappings are destroyed here and new ones will + * not be created until the end of the logging. + */ + if (npages && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES)) + kvm_mmu_slot_remove_write_access(kvm, mem->slot); spin_unlock(&kvm->mmu_lock); /* * If memory slot is created, or moved, we need to clear all diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e45c20ca422a..f689a6d7f9d4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -817,7 +817,6 @@ int __kvm_set_memory_region(struct kvm *kvm, if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { if (kvm_create_dirty_bitmap(&new) < 0) goto out_free; - /* destroy any largepage mappings for dirty tracking */ } if (!npages || base_gfn != old.base_gfn) { |