KVM: selftests: Keep track of memslots more efficiently

The KVM selftest framework was using a simple list for keeping track of
the memslots currently in use.
This resulted in lookups and adding a single memslot being O(n), the
later due to linear scanning of the existing memslot set to check for
the presence of any conflicting entries.

Before this change, benchmarking high count of memslots was more or less
impossible as pretty much all the benchmark time was spent in the
selftest framework code.

We can simply use a rbtree for keeping track of both of gfn and hva.
We don't need an interval tree for hva here as we can't have overlapping
memslots because we allocate a completely new memory chunk for each new
memslot.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-Id: <b12749d47ee860468240cf027412c91b76dbe3db.1618253574.git.maciej.szmigiero@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/tools/testing/selftests/kvm/lib/kvm_util_internal.h b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
index 91ce1b5d480b..b30e8c7b119b 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util_internal.h
+++ b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
@@ -8,6 +8,9 @@
 #ifndef SELFTEST_KVM_UTIL_INTERNAL_H
 #define SELFTEST_KVM_UTIL_INTERNAL_H
 
+#include "linux/hashtable.h"
+#include "linux/rbtree.h"
+
 #include "sparsebit.h"
 
 struct userspace_mem_region {
@@ -18,7 +21,9 @@ struct userspace_mem_region {
 	void *host_mem;
 	void *mmap_start;
 	size_t mmap_size;
-	struct list_head list;
+	struct rb_node gpa_node;
+	struct rb_node hva_node;
+	struct hlist_node slot_node;
 };
 
 struct vcpu {
@@ -31,6 +36,12 @@ struct vcpu {
 	uint32_t dirty_gfns_count;
 };
 
+struct userspace_mem_regions {
+	struct rb_root gpa_tree;
+	struct rb_root hva_tree;
+	DECLARE_HASHTABLE(slot_hash, 9);
+};
+
 struct kvm_vm {
 	int mode;
 	unsigned long type;
@@ -43,7 +54,7 @@ struct kvm_vm {
 	unsigned int va_bits;
 	uint64_t max_gfn;
 	struct list_head vcpus;
-	struct list_head userspace_mem_regions;
+	struct userspace_mem_regions regions;
 	struct sparsebit *vpages_valid;
 	struct sparsebit *vpages_mapped;
 	bool has_irqchip;