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Subject[PATCH 1/7] KVM: Write protect the updated slot only when we start dirty logging
This is needed to make kvm_mmu_slot_remove_write_access() rmap based:
otherwise we may end up using invalid rmap's.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
---
arch/x86/kvm/x86.c | 9 ++++++++-
virt/kvm/kvm_main.c | 1 -
2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1c9c834..9451efa 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6897,7 +6897,14 @@ 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 ((mem->flags & KVM_MEM_LOG_DIRTY_PAGES) &&
+ !(old.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 bd31096..0ef5daa 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -805,7 +805,6 @@ 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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