From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
Do a quick lookup for possibly overlapping gfns when creating or moving
a memslot instead of performing a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 36 +++++++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5fea467d6fec..78dad8c6376f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1667,6 +1667,30 @@ static int kvm_delete_memslot(struct kvm *kvm,
return kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE);
}
+static bool kvm_check_memslot_overlap(struct kvm_memslots *slots,
+ struct kvm_memory_slot *nslot)
+{
+ int idx = slots->node_idx;
+ gfn_t nend = nslot->base_gfn + nslot->npages;
+ struct rb_node *node;
+
+ kvm_for_each_memslot_in_gfn_range(node, slots, nslot->base_gfn, nend) {
+ struct kvm_memory_slot *cslot;
+ gfn_t cend;
+
+ cslot = container_of(node, struct kvm_memory_slot, gfn_node[idx]);
+ cend = cslot->base_gfn + cslot->npages;
+ if (cslot->id == nslot->id)
+ continue;
+
+ /* kvm_for_each_in_gfn_no_more() guarantees that cslot->base_gfn < nend */
+ if (cend > nslot->base_gfn)
+ return true;
+ }
+
+ return false;
+}
+
/*
* Allocate some memory and give it an address in the guest physical address
* space.
@@ -1752,16 +1776,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
}
if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
- int bkt;
-
/* Check for overlaps */
- kvm_for_each_memslot(tmp, bkt, __kvm_memslots(kvm, as_id)) {
- if (tmp->id == id)
- continue;
- if (!((new.base_gfn + new.npages <= tmp->base_gfn) ||
- (new.base_gfn >= tmp->base_gfn + tmp->npages)))
- return -EEXIST;
- }
+ if (kvm_check_memslot_overlap(__kvm_memslots(kvm, as_id),
+ &new))
+ return -EEXIST;
}
/* Allocate/free page dirty bitmap as needed */
