kvm: Fix memory slot generation updates
Previous patch "kvm: Minor memory slot optimization" (b7f69c555ca43)
overlooked the generation field of the memory slots. Re-using the
original memory slots left us with with two slightly different memory
slots with the same generation. To fix this, make update_memslots()
take a new parameter to specify the last generation. This also makes
generation management more explicit to avoid such problems in the future.
Reported-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 32fdc45..cbe0d68 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -428,7 +428,8 @@
void kvm_get_kvm(struct kvm *kvm);
void kvm_put_kvm(struct kvm *kvm);
-void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new);
+void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new,
+ u64 last_generation);
static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
{
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index bd31096..14cbae8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -672,7 +672,8 @@
slots->id_to_index[slots->memslots[i].id] = i;
}
-void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new)
+void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new,
+ u64 last_generation)
{
if (new) {
int id = new->id;
@@ -684,7 +685,7 @@
sort_memslots(slots);
}
- slots->generation++;
+ slots->generation = last_generation + 1;
}
static int check_memory_region_flags(struct kvm_userspace_memory_region *mem)
@@ -819,7 +820,7 @@
slot = id_to_memslot(slots, mem->slot);
slot->flags |= KVM_MEMSLOT_INVALID;
- update_memslots(slots, NULL);
+ update_memslots(slots, NULL, kvm->memslots->generation);
old_memslots = kvm->memslots;
rcu_assign_pointer(kvm->memslots, slots);
@@ -867,7 +868,7 @@
memset(&new.arch, 0, sizeof(new.arch));
}
- update_memslots(slots, &new);
+ update_memslots(slots, &new, kvm->memslots->generation);
old_memslots = kvm->memslots;
rcu_assign_pointer(kvm->memslots, slots);
synchronize_srcu_expedited(&kvm->srcu);
