[PATCH v6 17/27] vfio: selftests: Add vfio_pci_liveupdate_uapi_test

[Vipin Sharma <vipinsh@google.com>]

From: David Matlack <dmatlack@google.com>

Add a selftest to exercise preserving various VFIO files through
/dev/liveupdate. Only the VFIO cdev files of devices in noiommu mode can
be preserved. Ensure that preserving the cdev file of a device that is
not in noiommu mode fails, and that everything else (group-based device
files, group files, and container files) fails too.

In FIXTURE_SETUP, probe luo_session_preserve_fd() on the bound cdev FD
in a temporary session for iommufd variants and skip if LUO returns
-ENOENT, so the test skips cleanly when CONFIG_VFIO_PCI_LIVEUPDATE=n or
when the target device does not support VFIO PCI Live Update (e.g. an
SR-IOV VF).

Signed-off-by: David Matlack <dmatlack@google.com>
Co-developed-by: Vipin Sharma <vipinsh@google.com>
Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
 tools/testing/selftests/vfio/Makefile         |   1 +
 .../vfio/vfio_pci_liveupdate_uapi_test.c      | 126 ++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index 55e1e1843090..c2764fcef31d 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -13,6 +13,7 @@ TEST_GEN_PROGS += vfio_pci_device_test
 TEST_GEN_PROGS += vfio_pci_device_init_perf_test
 TEST_GEN_PROGS += vfio_pci_driver_test
 TEST_GEN_PROGS += vfio_pci_sriov_uapi_test
+TEST_GEN_PROGS += vfio_pci_liveupdate_uapi_test
 
 TEST_FILES += scripts/cleanup.sh
 TEST_FILES += scripts/lib.sh
diff --git a/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c b/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c
new file mode 100644
index 000000000000..da25ea4e2b1e
--- /dev/null
+++ b/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <libliveupdate.h>
+#include <libvfio.h>
+#include <kselftest_harness.h>
+
+static const char *device_bdf;
+
+FIXTURE(vfio_pci_liveupdate_uapi_test) {
+	int luo_fd;
+	int session_fd;
+	struct iommu *iommu;
+	struct vfio_pci_device *device;
+};
+
+/*
+ * LUO fails with -ENOENT if no file handler accepts a file. For the bound VFIO
+ * cdev file of a device, that means that the kernel lacks VFIO PCI Live Update
+ * support (CONFIG_VFIO_PCI_LIVEUPDATE=n) or that vfio-pci does not support
+ * preserving the device (e.g. an SR-IOV VF).
+ */
+static bool device_preserve_supported(int luo_fd, int device_fd)
+{
+	int session_fd;
+	int ret;
+
+	session_fd = luo_create_session(luo_fd, "probe");
+	VFIO_ASSERT_GE(session_fd, 0);
+
+	ret = luo_session_preserve_fd(session_fd, device_fd, 0);
+
+	/* Closing the session unpreserves the device. */
+	VFIO_ASSERT_EQ(close(session_fd), 0);
+
+	return ret != -ENOENT;
+}
+
+FIXTURE_VARIANT(vfio_pci_liveupdate_uapi_test) {
+	const char *iommu_mode;
+};
+
+#define FIXTURE_VARIANT_ADD_IOMMU_MODE(_iommu_mode)			\
+FIXTURE_VARIANT_ADD(vfio_pci_liveupdate_uapi_test, _iommu_mode) {	\
+	.iommu_mode = #_iommu_mode,					\
+}
+
+FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES();
+#undef FIXTURE_VARIANT_ADD_IOMMU_MODE
+
+FIXTURE_SETUP(vfio_pci_liveupdate_uapi_test)
+{
+	self->luo_fd = luo_open_device();
+	ASSERT_GT(self->luo_fd, 0);
+
+	self->session_fd = luo_create_session(self->luo_fd, "session");
+	ASSERT_GT(self->session_fd, 0);
+
+	self->iommu = iommu_init(variant->iommu_mode);
+	self->device = vfio_pci_device_init(device_bdf, self->iommu);
+
+	if (self->iommu->iommufd &&
+	    !device_preserve_supported(self->luo_fd, self->device->fd))
+		SKIP(return, "Live Update of %s is not supported", device_bdf);
+}
+
+FIXTURE_TEARDOWN(vfio_pci_liveupdate_uapi_test)
+{
+	if (self->device)
+		vfio_pci_device_cleanup(self->device);
+	if (self->iommu)
+		iommu_cleanup(self->iommu);
+	if (self->session_fd > 0)
+		close(self->session_fd);
+	if (self->luo_fd > 0)
+		close(self->luo_fd);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_device)
+{
+	int ret;
+
+	ret = luo_session_preserve_fd(self->session_fd, self->device->fd, 0);
+
+	/*
+	 * Only VFIO cdev files of devices in noiommu mode can be preserved;
+	 * device files obtained through a VFIO group never can.
+	 */
+	ASSERT_EQ(ret, self->iommu->iommufd ? -EOPNOTSUPP : -ENOENT);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_group_fails)
+{
+	int ret;
+
+	if (self->iommu->iommufd)
+		SKIP(return, "iommufd-mode does not have group files");
+
+	ret = luo_session_preserve_fd(self->session_fd, self->device->group_fd, 0);
+	ASSERT_EQ(ret, -ENOENT);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_container_fails)
+{
+	int ret;
+
+	if (self->iommu->iommufd)
+		SKIP(return, "iommufd-mode does not have container files");
+
+	ret = luo_session_preserve_fd(self->session_fd, self->iommu->container_fd, 0);
+	ASSERT_EQ(ret, -ENOENT);
+}
+
+int main(int argc, char *argv[])
+{
+	int fd;
+
+	fd = luo_open_device();
+	if (fd < 0)
+		ksft_exit_skip("open(%s) failed: %s, skipping\n",
+			       LUO_DEVICE, strerror(errno));
+
+	close(fd);
+
+	device_bdf = vfio_selftests_get_bdf(&argc, argv);
+	return test_harness_run(argc, argv);
+}
-- 
2.56.0.317.g454f8302e1-goog