Re: [PATCH 32/34] KVM: selftests: Add basic selftest for guest_memfd()

From: Fuad Tabba
Date: Tue Nov 07 2023 - 08:11:33 EST

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Hi,

On Sun, Nov 5, 2023 at 4:35 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
> From: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx>
> Co-developed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Co-developed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Co-developed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Message-Id: <20231027182217.3615211-35-seanjc@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/Makefile | 1 +
> .../testing/selftests/kvm/guest_memfd_test.c | 206 ++++++++++++++++++
> 2 files changed, 207 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 ecdea5e7afa8..fd3b30a4ca7b 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -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
> 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..ea0ae7e25330
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/guest_memfd_test.c
> @@ -0,0 +1,206 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright Intel Corporation, 2023
> + *
> + * Author: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> + */
> +
> +#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>

The include ordering should be fixed. Otherwise,

Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
Tested-by: Fuad Tabba <tabba@xxxxxxxxxx>

Cheers,
/fuad

> +
> +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);
> +}
> --
> 2.39.1
>
>

Next message: Vincent Guittot: "Re: [PATCH v5 7/7] arm64/amu: Use capacity_ref_freq to set AMU ratio"
Previous message: Danilo Krummrich: "Re: [PATCH drm-misc-next v3] drm/sched: implement dynamic job-flow control"
In reply to: Paolo Bonzini: "[PATCH 32/34] KVM: selftests: Add basic selftest for guest_memfd()"
Next in thread: Paolo Bonzini: "[PATCH 35/34] KVM: Prepare for handling only shared mappings in mmu_notifier events"
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