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.
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@xxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 8 +++++++-
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 1c9c834..add5e48 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 e45c20c..f689a6d 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) {
--
1.7.5.4
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