Commit 8a89efd4 authored by Chao Peng's avatar Chao Peng Committed by Paolo Bonzini
Browse files

KVM: selftests: Add basic selftest for guest_memfd() 



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: default avatarChao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: default avatarAckerley Tng <ackerleytng@google.com>
Signed-off-by: default avatarAckerley Tng <ackerleytng@google.com>
Co-developed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Co-developed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-35-seanjc@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2feabb85

tools/testing/selftests/kvm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -134,6 +134,7 @@ 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

tools/testing/selftests/kvm/guest_memfd_test.c

0 → 100644
+207 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright Intel Corporation, 2023

 *

 * Author: Chao Peng <chao.p.peng@linux.intel.com>

 */



#define _GNU_SOURCE

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <errno.h>

#include <stdio.h>

#include <fcntl.h>



#include <linux/bitmap.h>

#include <linux/falloc.h>

#include <sys/mman.h>

#include <sys/types.h>

#include <sys/stat.h>



#include "test_util.h"

#include "kvm_util_base.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)

{

	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);

	}



	for (flag = 1; flag; flag <<= 1) {

		uint64_t bit;



		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);

}