KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers

With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
we have to get the transparent hugepage size for HVA alignment. With the
new helpers, we can use get_backing_src_pagesz() to check whether THP is
configured and then get the exact configured hugepage size.

As different architectures may have different THP page sizes configured,
this can get the accurate THP page sizes on any platform.
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-Id: <20210330080856.14940-10-wangyanan55@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -18,7 +18,6 @@
 #include <unistd.h>
 #include <linux/kernel.h>
 
-#define KVM_UTIL_PGS_PER_HUGEPG 512
 #define KVM_UTIL_MIN_PFN	2
 
 static int vcpu_mmap_sz(void);
@@ -688,7 +687,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 {
 	int ret;
 	struct userspace_mem_region *region;
-	size_t huge_page_size = KVM_UTIL_PGS_PER_HUGEPG * vm->page_size;
+	size_t backing_src_pagesz = get_backing_src_pagesz(src_type);
 	size_t alignment;
 
 	TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
@@ -750,7 +749,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 #endif
 
 	if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
-		alignment = max(huge_page_size, alignment);
+		alignment = max(backing_src_pagesz, alignment);
 
 	/* Add enough memory to align up if necessary */
 	if (alignment > 1)
@@ -769,22 +768,13 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 	region->host_mem = align(region->mmap_start, alignment);
 
 	/* As needed perform madvise */
-	if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
-		struct stat statbuf;
-
-		ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
-		TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
-			    "stat /sys/kernel/mm/transparent_hugepage");
-
-		TEST_ASSERT(ret == 0 || src_type != VM_MEM_SRC_ANONYMOUS_THP,
-			    "VM_MEM_SRC_ANONYMOUS_THP requires THP to be configured in the host kernel");
-
-		if (ret == 0) {
-			ret = madvise(region->host_mem, npages * vm->page_size,
-				      src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
-			TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %x",
-				    region->host_mem, npages * vm->page_size, src_type);
-		}
+	if ((src_type == VM_MEM_SRC_ANONYMOUS ||
+	     src_type == VM_MEM_SRC_ANONYMOUS_THP) && thp_configured()) {
+		ret = madvise(region->host_mem, npages * vm->page_size,
+			      src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
+		TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %s",
+			    region->host_mem, npages * vm->page_size,
+			    vm_mem_backing_src_alias(src_type)->name);
 	}
 
 	region->unused_phy_pages = sparsebit_alloc();