KVM: selftests: memslot_perf_test: Use data->nslots in prepare_vm()

In prepare_vm(), 'data->nslots' is assigned with 'max_mem_slots - 1'
at the beginning, meaning they are interchangeable.

Use 'data->nslots' isntead of 'max_mem_slots - 1'. With this, it
becomes easier to move the logic of probing number of slots into
upper layer in subsequent patches.

No functional change intended.
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221020071209.559062-2-gshan@redhat.com

tools/testing/selftests/kvm/memslot_perf_test.c

@@ -280,14 +280,14 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
 	ucall_init(data->vm, NULL);
 
 	pr_info_v("Adding slots 1..%i, each slot with %"PRIu64" pages + %"PRIu64" extra pages last\n",
-		max_mem_slots - 1, data->pages_per_slot, rempages);
+		data->nslots, data->pages_per_slot, rempages);
 
 	clock_gettime(CLOCK_MONOTONIC, &tstart);
-	for (slot = 1, guest_addr = MEM_GPA; slot < max_mem_slots; slot++) {
+	for (slot = 1, guest_addr = MEM_GPA; slot <= data->nslots; slot++) {
 		uint64_t npages;
 
 		npages = data->pages_per_slot;
-		if (slot == max_mem_slots - 1)
+		if (slot == data->nslots)
 			npages += rempages;
 
 		vm_userspace_mem_region_add(data->vm, VM_MEM_SRC_ANONYMOUS,
@@ -297,12 +297,12 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
 	}
 	*slot_runtime = timespec_elapsed(tstart);
 
-	for (slot = 0, guest_addr = MEM_GPA; slot < max_mem_slots - 1; slot++) {
+	for (slot = 0, guest_addr = MEM_GPA; slot < data->nslots; slot++) {
 		uint64_t npages;
 		uint64_t gpa;
 
 		npages = data->pages_per_slot;
-		if (slot == max_mem_slots - 2)
+		if (slot == data->nslots - 1)
 			npages += rempages;
 
 		gpa = vm_phy_pages_alloc(data->vm, npages, guest_addr,