KVM: introduce a table to map slot id to index in memslots array
The operation of getting dirty log is frequent when framebuffer-based
displays are used(for example, Xwindow), so, we introduce a mapping table
to speed up id_to_memslot()
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9efdf5c..8c5c303 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -239,6 +239,8 @@
struct kvm_memslots {
u64 generation;
struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
+ /* The mapping table from slot id to the index in memslots[]. */
+ int id_to_index[KVM_MEM_SLOTS_NUM];
};
struct kvm {
@@ -341,14 +343,13 @@
static inline struct kvm_memory_slot *
id_to_memslot(struct kvm_memslots *slots, int id)
{
- int i;
+ int index = slots->id_to_index[id];
+ struct kvm_memory_slot *slot;
- for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
- if (slots->memslots[i].id == id)
- return &slots->memslots[i];
+ slot = &slots->memslots[index];
- WARN_ON(1);
- return NULL;
+ WARN_ON(slot->id != id);
+ return slot;
}
#define HPA_MSB ((sizeof(hpa_t) * 8) - 1)