[PATCH RFC v4 42/44] KVM: selftests: Add script to exercise private_mem_conversions_test

Ackerley Tng
2026-03-26T22:25:51Z

Add a wrapper script to simplify running the private_mem_conversions_test
with a variety of configurations. Manually invoking the test for all
supported memory backing source types is tedious.

The script automatically detects the availability of 2MB and 1GB hugepages
and builds a list of source types to test. It then iterates through the
list, running the test for each type with both a single memslot and
multiple memslots.

This makes it easier to get comprehensive test coverage across different
memory configurations.

Add and use a helper program in C to be able to read
KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES as defined in header files and then
issue the ioctl to read the KVM CAP.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
tools/testing/selftests/kvm/Makefile.kvm | 4 +
.../selftests/kvm/kvm_has_gmem_attributes.c | 17 +++
.../kvm/x86/private_mem_conversions_test.sh | 128 +++++++++++++++++++++
3 files changed, 149 insertions(+)

diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index 0e2a9adfca57e..c326aecfeebb0 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -54,6 +54,7 @@ LIBKVM_loongarch += lib/loongarch/exception.S

# Non-compiled test targets
TEST_PROGS_x86 += x86/nx_huge_pages_test.sh
+TEST_PROGS_x86 += x86/private_mem_conversions_test.sh

# Compiled test targets valid on all architectures with libkvm support
TEST_GEN_PROGS_COMMON = demand_paging_test
@@ -65,6 +66,8 @@ TEST_GEN_PROGS_COMMON += kvm_create_max_vcpus
TEST_GEN_PROGS_COMMON += kvm_page_table_test
TEST_GEN_PROGS_COMMON += set_memory_region_test

+TEST_GEN_PROGS_EXTENDED_COMMON += kvm_has_gmem_attributes
+
# Compiled test targets
TEST_GEN_PROGS_x86 = $(TEST_GEN_PROGS_COMMON)
TEST_GEN_PROGS_x86 += x86/cpuid_test
@@ -242,6 +245,7 @@ SPLIT_TESTS += get-reg-list

TEST_PROGS += $(TEST_PROGS_$(ARCH))
TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(ARCH))
+TEST_GEN_PROGS_EXTENDED += $(TEST_GEN_PROGS_EXTENDED_COMMON)
TEST_GEN_PROGS_EXTENDED += $(TEST_GEN_PROGS_EXTENDED_$(ARCH))
LIBKVM += $(LIBKVM_$(ARCH))

diff --git a/tools/testing/selftests/kvm/kvm_has_gmem_attributes.c b/tools/testing/selftests/kvm/kvm_has_gmem_attributes.c
new file mode 100644
index 0000000000000..4f361349412fb
--- /dev/null
+++ b/tools/testing/selftests/kvm/kvm_has_gmem_attributes.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Utility to check if KVM supports guest_memfd attributes.
+ *
+ * Copyright (C) 2025, Google LLC.
+ */
+
+#include <stdio.h>
+
+#include "kvm_util.h"
+
+int main(void)
+{
+ printf("%u\n", kvm_check_cap(KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES) > 0);
+
+ return 0;
+}
diff --git a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.sh b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.sh
new file mode 100755
index 0000000000000..7179a4fcdd498
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.sh
@@ -0,0 +1,128 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Wrapper script which runs different test setups of
+# private_mem_conversions_test.
+#
+# Copyright (C) 2025, Google LLC.
+
+NUM_VCPUS_TO_TEST=4
+NUM_MEMSLOTS_TO_TEST=$NUM_VCPUS_TO_TEST
+
+# Required pages are based on the test setup in the C code.
+REQUIRED_NUM_2M_HUGEPAGES=$((1024 * NUM_VCPUS_TO_TEST))
+REQUIRED_NUM_1G_HUGEPAGES=$((2 * NUM_VCPUS_TO_TEST))
+
+get_hugepage_count() {
+ local page_size_kb=$1
+ local path="/sys/kernel/mm/hugepages/hugepages-${page_size_kb}kB/nr_hugepages"
+ if [ -f "$path" ]; then
+ cat "$path"
+ else
+ echo 0
+ fi
+}
+
+get_default_hugepage_size_in_kb() {
+ local size=$(grep "Hugepagesize:" /proc/meminfo | awk '{print $2}')
+ echo "$size"
+}
+
+run_tests() {
+ local executable_path=$1
+ local src_type=$2
+ local num_memslots=$3
+ local num_vcpus=$4
+
+ echo "$executable_path -s $src_type -m $num_memslots -n $num_vcpus"
+ "$executable_path" -s "$src_type" -m "$num_memslots" -n "$num_vcpus"
+}
+
+script_dir=$(dirname "$(realpath "$0")")
+test_executable="${script_dir}/private_mem_conversions_test"
+kvm_has_gmem_attributes_tool="${script_dir}/../kvm_has_gmem_attributes"
+
+if [ ! -f "$test_executable" ]; then
+ echo "Error: Test executable not found at '$test_executable'" >&2
+ exit 1
+fi
+
+if [ ! -f "$kvm_has_gmem_attributes_tool" ]; then
+ echo "Error: kvm_has_gmem_attributes utility not found at '$kvm_has_gmem_attributes_tool'" >&2
+ exit 1
+fi
+
+kvm_has_gmem_attributes=$("$kvm_has_gmem_attributes_tool" | tail -n1)
+
+if [ "$kvm_has_gmem_attributes" -eq 1 ]; then
+ backing_src_types=("shmem")
+else
+ hugepage_2mb_count=$(get_hugepage_count 2048)
+ hugepage_2mb_enabled=$((hugepage_2mb_count >= REQUIRED_NUM_2M_HUGEPAGES))
+ hugepage_1gb_count=$(get_hugepage_count 1048576)
+ hugepage_1gb_enabled=$((hugepage_1gb_count >= REQUIRED_NUM_1G_HUGEPAGES))
+
+ default_hugepage_size_kb=$(get_default_hugepage_size_in_kb)
+ hugepage_default_enabled=0
+ if [ "$default_hugepage_size_kb" -eq 2048 ]; then
+ hugepage_default_enabled=$hugepage_2mb_enabled
+ elif [ "$default_hugepage_size_kb" -eq 1048576 ]; then
+ hugepage_default_enabled=$hugepage_1gb_enabled
+ fi
+
+ backing_src_types=("anonymous" "anonymous_thp")
+
+ if [ "$hugepage_default_enabled" -eq 1 ]; then
+ backing_src_types+=("anonymous_hugetlb")
+ else
+ echo "skipping anonymous_hugetlb backing source type"
+ fi
+
+ if [ "$hugepage_2mb_enabled" -eq 1 ]; then
+ backing_src_types+=("anonymous_hugetlb_2mb")
+ else
+ echo "skipping anonymous_hugetlb_2mb backing source type"
+ fi
+
+ if [ "$hugepage_1gb_enabled" -eq 1 ]; then
+ backing_src_types+=("anonymous_hugetlb_1gb")
+ else
+ echo "skipping anonymous_hugetlb_1gb backing source type"
+ fi
+
+ backing_src_types+=("shmem")
+
+ if [ "$hugepage_default_enabled" -eq 1 ]; then
+ backing_src_types+=("shared_hugetlb")
+ else
+ echo "skipping shared_hugetlb backing source type"
+ fi
+fi
+
+return_code=0
+for i in "${!backing_src_types[@]}"; do
+ src_type=${backing_src_types[$i]}
+ if [ "$i" -gt 0 ]; then
+ echo
+ fi
+
+ if ! run_tests "$test_executable" "$src_type" 1 1; then
+ return_code=$?
+ echo "Test failed for source type '$src_type'. Arguments: -s $src_type -m 1 -n 1" >&2
+ break
+ fi
+
+ if ! run_tests "$test_executable" "$src_type" 1 "$NUM_VCPUS_TO_TEST"; then
+ return_code=$?
+ echo "Test failed for source type '$src_type'. Arguments: -s $src_type -m 1 -n $NUM_VCPUS_TO_TEST" >&2
+ break
+ fi
+
+ if ! run_tests "$test_executable" "$src_type" "$NUM_MEMSLOTS_TO_TEST" "$NUM_VCPUS_TO_TEST"; then
+ return_code=$?
+ echo "Test failed for source type '$src_type'. Arguments: -s $src_type -m $NUM_MEMSLOTS_TO_TEST -n $NUM_VCPUS_TO_TEST" >&2
+ break
+ fi
+done
+
+exit "$return_code"

--
2.53.0.1018.g2bb0e51243-goog