KVM: selftests: s390x: Provide additional num-guest-pages adjustment

s390 requires 1M aligned guest sizes. Embedding the rounding in
vm_adjust_num_guest_pages() allows us to remove it from a few
other places.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/demand_paging_test.c

@@ -378,10 +378,6 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
 	guest_num_pages = (vcpus * vcpu_memory_bytes) / guest_page_size;
 	guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
 
-#ifdef __s390x__
-	/* Round up to multiple of 1M (segment size) */
-	guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
-#endif
 	/*
 	 * If there should be more memory in the guest test region than there
 	 * can be pages in the guest, it will definitely cause problems.

tools/testing/selftests/kvm/dirty_log_test.c

@@ -296,10 +296,7 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
 	guest_num_pages = (1ul << (DIRTY_MEM_BITS -
 				   vm_get_page_shift(vm))) + 3;
 	guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
-#ifdef __s390x__
-	/* Round up to multiple of 1M (segment size) */
-	guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
-#endif
+
 	host_page_size = getpagesize();
 	host_num_pages = vm_num_host_pages(mode, guest_num_pages);
 

tools/testing/selftests/kvm/include/kvm_util.h

@@ -164,7 +164,13 @@ unsigned int vm_num_guest_pages(enum vm_guest_mode mode, unsigned int num_host_p
 static inline unsigned int
 vm_adjust_num_guest_pages(enum vm_guest_mode mode, unsigned int num_guest_pages)
 {
-	return vm_num_guest_pages(mode, vm_num_host_pages(mode, num_guest_pages));
+	unsigned int n;
+	n = vm_num_guest_pages(mode, vm_num_host_pages(mode, num_guest_pages));
+#ifdef __s390x__
+	/* s390 requires 1M aligned guest sizes */
+	n = (n + 255) & ~255;
+#endif
+	return n;
 }
 
 struct kvm_userspace_memory_region *