From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
There is no need to copy the whole memslot data after releasing
slots_arch_lock for a moment to install temporary memslots copy in
kvm_set_memslot() since this lock only protects the arch field of each
memslot.
Just resync this particular field after reacquiring slots_arch_lock.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7000efff1425..272bc86a0e69 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1494,6 +1494,15 @@ static void kvm_copy_memslots(struct kvm_memslots *to,
memcpy(to, from, kvm_memslots_size(from->used_slots));
}
+static void kvm_copy_memslots_arch(struct kvm_memslots *to,
+ struct kvm_memslots *from)
+{
+ int i;
+
+ for (i = 0; i < from->used_slots; i++)
+ to->memslots[i].arch = from->memslots[i].arch;
+}
+
/*
* Note, at a minimum, the current number of used slots must be allocated, even
* when deleting a memslot, as we need a complete duplicate of the memslots for
@@ -1579,10 +1588,10 @@ static int kvm_set_memslot(struct kvm *kvm,
/*
* The arch-specific fields of the memslots could have changed
* between releasing the slots_arch_lock in
- * install_new_memslots and here, so get a fresh copy of the
- * slots.
+ * install_new_memslots and here, so get a fresh copy of these
+ * fields.
*/
- kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id));
+ kvm_copy_memslots_arch(slots, __kvm_memslots(kvm, as_id));
}
r = kvm_arch_prepare_memory_region(kvm, old, new, mem, change);
@@ -1599,8 +1608,6 @@ static int kvm_set_memslot(struct kvm *kvm,
out_slots:
if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
- slot = id_to_memslot(slots, old->id);
- slot->flags &= ~KVM_MEMSLOT_INVALID;
slots = install_new_memslots(kvm, as_id, slots);
} else {
mutex_unlock(&kvm->slots_arch_lock);
