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charset="utf-8" Message-Id: <20261106-gmem-alternative-providers-v3-10-8484dde66a7e@google.com> References: <20261106-gmem-alternative-providers-v3-0-8484dde66a7e@google.com> In-Reply-To: <20261106-gmem-alternative-providers-v3-0-8484dde66a7e@google.com> To: Alexey Kardashevskiy , "Aneesh Kumar K.V" , Christian Brauner , David Hildenbrand , David Woodhouse , Fred Griffoul , Jacob Pan , Jianxiong Gao , John Starks , Michael Roth , Paolo Bonzini , Samiullah Khawaja , Sean Christopherson , Suzuki K Poulose , Tarun Sahu , Vishal Annapurve , Xu Yilun , Fuad Tabba Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Ackerley Tng X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=ed25519-sha256; t=1794011809; l=3539; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=lpdQUuXZRi5HMPPsDaXRCAlhoLcAGTXnceeQBzFXLus=; b=8gMlAhCQDehpdhBKMnVKx7w1xPC7T5I9VIapWU//NYUwuh9viMkkDkY8Lth7l4Nzmwxv3uzv3 0m7ExSF1OwwBGyGeTkzOhAjzWOq3kzo+pxYPQZad5a7uLNh6tMiN/Ux X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com Content-Transfer-Encoding: 7bit From: Ackerley Tng Test that guest_memfd creation fails with -EINVAL when passed a resource pool fd for a mount that has swap enabled. Signed-off-by: Ackerley Tng --- tools/testing/selftests/kvm/guest_memfd_test.c | 70 ++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index d62ae23256083..205f822e10c6c 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -13,7 +13,9 @@ #include #include +#include #include +#include #include #include @@ -478,6 +480,73 @@ static void test_resource_fd_memfd(struct kvm_vm *vm) close(file_fd); } +static int create_tmpfs_pool_fd(const char *huge, bool noswap, size_t size) +{ + char size_str[32]; + char template[] = "/tmp/gmem_test_dir_XXXXXX"; + char *mount_dir; + int fs_fd, mnt_fd, dir_fd; + + TEST_ASSERT(size && IS_ALIGNED(size, page_size), + "Pool size '0x%zx' must be positive and page-aligned", size); + + fs_fd = syscall(__NR_fsopen, "tmpfs", FSOPEN_CLOEXEC); + TEST_ASSERT(fs_fd >= 0, "fsopen failed"); + + if (noswap) + TEST_ASSERT(!syscall(__NR_fsconfig, fs_fd, FSCONFIG_SET_FLAG, + "noswap", NULL, 0), "fsconfig noswap failed"); + + if (huge) + TEST_ASSERT(!syscall(__NR_fsconfig, fs_fd, FSCONFIG_SET_STRING, + "huge", huge, 0), "fsconfig huge failed"); + + snprintf(size_str, sizeof(size_str), "%zu", size); + TEST_ASSERT(!syscall(__NR_fsconfig, fs_fd, FSCONFIG_SET_STRING, + "size", size_str, 0), "fsconfig size failed"); + + TEST_ASSERT(!syscall(__NR_fsconfig, fs_fd, FSCONFIG_CMD_CREATE, + NULL, NULL, 0), "fsconfig create failed"); + + mnt_fd = syscall(__NR_fsmount, fs_fd, FSMOUNT_CLOEXEC, 0); + TEST_ASSERT(mnt_fd > 0, "fsmount failed"); + close(fs_fd); + + mount_dir = mkdtemp(template); + TEST_ASSERT(mount_dir, "mkdtemp failed"); + + TEST_ASSERT(!syscall(__NR_move_mount, mnt_fd, "", AT_FDCWD, mount_dir, + MOVE_MOUNT_F_EMPTY_PATH), "move_mount failed"); + close(mnt_fd); + + dir_fd = open(mount_dir, O_RDONLY | O_DIRECTORY | O_CLOEXEC); + TEST_ASSERT(dir_fd >= 0, "open tmpfs mount directory failed"); + + /* + * Detach mount from namespace so removing mount_dir upon exit or + * unmount doesn't conflict, while dir_fd retains the active mount. + */ + TEST_ASSERT(!umount2(mount_dir, MNT_DETACH), "umount2 failed"); + TEST_ASSERT(!rmdir(mount_dir), "rmdir failed"); + + return dir_fd; +} + +static void test_resource_fd_tmpfs_swap(struct kvm_vm *vm) +{ + int pool_fd, fd; + + pool_fd = create_tmpfs_pool_fd("never", false, page_size); + + fd = __vm_create_guest_memfd_resource(vm, page_size, + GUEST_MEMFD_FLAG_USE_RESOURCE, + pool_fd); + TEST_ASSERT(fd < 0, "guest_memfd with swap-enabled tmpfs should fail"); + TEST_ASSERT_EQ(errno, EINVAL); + + close(pool_fd); +} + #define ____gmem_test(__test, __vm, __flags, __gmem_size, args...) \ do { \ int fd = vm_create_guest_memfd(__vm, __gmem_size, __flags); \ @@ -539,6 +608,7 @@ static void test_guest_memfd(unsigned long vm_type) test_resource_fd_invalid(vm); test_resource_fd_unsupported_fs(vm); test_resource_fd_memfd(vm); + test_resource_fd_tmpfs_swap(vm); __test_guest_memfd(vm, 0); -- 2.56.0.455.g6c5a503b38-goog