[PATCH v13 34/35] KVM: selftests: Add basic selftest for guest_memfd()
Sean Christopherson
seanjc at google.com
Sat Oct 28 05:22:16 AEDT 2023
From: Chao Peng <chao.p.peng at linux.intel.com>
Add a selftest to verify the basic functionality of guest_memfd():
+ file descriptor created with the guest_memfd() ioctl does not allow
read/write/mmap operations
+ file size and block size as returned from fstat are as expected
+ fallocate on the fd checks that offset/length on
fallocate(FALLOC_FL_PUNCH_HOLE) should be page aligned
+ invalid inputs (misaligned size, invalid flags) are rejected
+ file size and inode are unique (the innocuous-sounding
anon_inode_getfile() backs all files with a single inode...)
Signed-off-by: Chao Peng <chao.p.peng at linux.intel.com>
Co-developed-by: Ackerley Tng <ackerleytng at google.com>
Signed-off-by: Ackerley Tng <ackerleytng at google.com>
Co-developed-by: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
Co-developed-by: Sean Christopherson <seanjc at google.com>
Signed-off-by: Sean Christopherson <seanjc at google.com>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../testing/selftests/kvm/guest_memfd_test.c | 221 ++++++++++++++++++
2 files changed, 222 insertions(+)
create mode 100644 tools/testing/selftests/kvm/guest_memfd_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index b709a52d5cdb..2b1ef809d73a 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -124,6 +124,7 @@ TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
+TEST_GEN_PROGS_x86_64 += guest_memfd_test
TEST_GEN_PROGS_x86_64 += guest_print_test
TEST_GEN_PROGS_x86_64 += hardware_disable_test
TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
new file mode 100644
index 000000000000..c15de9852316
--- /dev/null
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright Intel Corporation, 2023
+ *
+ * Author: Chao Peng <chao.p.peng at linux.intel.com>
+ */
+
+#define _GNU_SOURCE
+#include "test_util.h"
+#include "kvm_util_base.h"
+#include <linux/bitmap.h>
+#include <linux/falloc.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+static void test_file_read_write(int fd)
+{
+ char buf[64];
+
+ TEST_ASSERT(read(fd, buf, sizeof(buf)) < 0,
+ "read on a guest_mem fd should fail");
+ TEST_ASSERT(write(fd, buf, sizeof(buf)) < 0,
+ "write on a guest_mem fd should fail");
+ TEST_ASSERT(pread(fd, buf, sizeof(buf), 0) < 0,
+ "pread on a guest_mem fd should fail");
+ TEST_ASSERT(pwrite(fd, buf, sizeof(buf), 0) < 0,
+ "pwrite on a guest_mem fd should fail");
+}
+
+static void test_mmap(int fd, size_t page_size)
+{
+ char *mem;
+
+ mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ TEST_ASSERT_EQ(mem, MAP_FAILED);
+}
+
+static void test_file_size(int fd, size_t page_size, size_t total_size)
+{
+ struct stat sb;
+ int ret;
+
+ ret = fstat(fd, &sb);
+ TEST_ASSERT(!ret, "fstat should succeed");
+ TEST_ASSERT_EQ(sb.st_size, total_size);
+ TEST_ASSERT_EQ(sb.st_blksize, page_size);
+}
+
+static void test_fallocate(int fd, size_t page_size, size_t total_size)
+{
+ int ret;
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, total_size);
+ TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ page_size - 1, page_size);
+ TEST_ASSERT(ret, "fallocate with unaligned offset should fail");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size, page_size);
+ TEST_ASSERT(ret, "fallocate beginning at total_size should fail");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size + page_size, page_size);
+ TEST_ASSERT(ret, "fallocate beginning after total_size should fail");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ total_size, page_size);
+ TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) at total_size should succeed");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ total_size + page_size, page_size);
+ TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) after total_size should succeed");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ page_size, page_size - 1);
+ TEST_ASSERT(ret, "fallocate with unaligned size should fail");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ page_size, page_size);
+ TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) with aligned offset and size should succeed");
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, page_size, page_size);
+ TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
+}
+
+static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size)
+{
+ struct {
+ off_t offset;
+ off_t len;
+ } testcases[] = {
+ {0, 1},
+ {0, page_size - 1},
+ {0, page_size + 1},
+
+ {1, 1},
+ {1, page_size - 1},
+ {1, page_size},
+ {1, page_size + 1},
+
+ {page_size, 1},
+ {page_size, page_size - 1},
+ {page_size, page_size + 1},
+ };
+ int ret, i;
+
+ for (i = 0; i < ARRAY_SIZE(testcases); i++) {
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+ testcases[i].offset, testcases[i].len);
+ TEST_ASSERT(ret == -1 && errno == EINVAL,
+ "PUNCH_HOLE with !PAGE_SIZE offset (%lx) and/or length (%lx) should fail",
+ testcases[i].offset, testcases[i].len);
+ }
+}
+
+static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
+{
+ uint64_t valid_flags = 0;
+ size_t page_size = getpagesize();
+ uint64_t flag;
+ size_t size;
+ int fd;
+
+ for (size = 1; size < page_size; size++) {
+ fd = __vm_create_guest_memfd(vm, size, 0);
+ TEST_ASSERT(fd == -1 && errno == EINVAL,
+ "guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
+ size);
+ }
+
+ if (thp_configured()) {
+ for (size = page_size * 2; size < get_trans_hugepagesz(); size += page_size) {
+ fd = __vm_create_guest_memfd(vm, size, KVM_GUEST_MEMFD_ALLOW_HUGEPAGE);
+ TEST_ASSERT(fd == -1 && errno == EINVAL,
+ "guest_memfd() with non-hugepage-aligned page size '0x%lx' should fail with EINVAL",
+ size);
+ }
+
+ valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE;
+ }
+
+ for (flag = 1; flag; flag <<= 1) {
+ uint64_t bit;
+
+ if (flag & valid_flags)
+ continue;
+
+ fd = __vm_create_guest_memfd(vm, page_size, flag);
+ TEST_ASSERT(fd == -1 && errno == EINVAL,
+ "guest_memfd() with flag '0x%lx' should fail with EINVAL",
+ flag);
+
+ for_each_set_bit(bit, &valid_flags, 64) {
+ fd = __vm_create_guest_memfd(vm, page_size, flag | BIT_ULL(bit));
+ TEST_ASSERT(fd == -1 && errno == EINVAL,
+ "guest_memfd() with flags '0x%llx' should fail with EINVAL",
+ flag | BIT_ULL(bit));
+ }
+ }
+}
+
+static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
+{
+ int fd1, fd2, ret;
+ struct stat st1, st2;
+
+ fd1 = __vm_create_guest_memfd(vm, 4096, 0);
+ TEST_ASSERT(fd1 != -1, "memfd creation should succeed");
+
+ ret = fstat(fd1, &st1);
+ TEST_ASSERT(ret != -1, "memfd fstat should succeed");
+ TEST_ASSERT(st1.st_size == 4096, "memfd st_size should match requested size");
+
+ fd2 = __vm_create_guest_memfd(vm, 8192, 0);
+ TEST_ASSERT(fd2 != -1, "memfd creation should succeed");
+
+ ret = fstat(fd2, &st2);
+ TEST_ASSERT(ret != -1, "memfd fstat should succeed");
+ TEST_ASSERT(st2.st_size == 8192, "second memfd st_size should match requested size");
+
+ ret = fstat(fd1, &st1);
+ TEST_ASSERT(ret != -1, "memfd fstat should succeed");
+ TEST_ASSERT(st1.st_size == 4096, "first memfd st_size should still match requested size");
+ TEST_ASSERT(st1.st_ino != st2.st_ino, "different memfd should have different inode numbers");
+}
+
+int main(int argc, char *argv[])
+{
+ size_t page_size;
+ size_t total_size;
+ int fd;
+ struct kvm_vm *vm;
+
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
+
+ page_size = getpagesize();
+ total_size = page_size * 4;
+
+ vm = vm_create_barebones();
+
+ test_create_guest_memfd_invalid(vm);
+ test_create_guest_memfd_multiple(vm);
+
+ fd = vm_create_guest_memfd(vm, total_size, 0);
+
+ test_file_read_write(fd);
+ test_mmap(fd, page_size);
+ test_file_size(fd, page_size, total_size);
+ test_fallocate(fd, page_size, total_size);
+ test_invalid_punch_hole(fd, page_size, total_size);
+
+ close(fd);
+}
--
2.42.0.820.g83a721a137-goog
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