[PATCH v6 24/27] vfio: selftests: Test preserving noiommu devices in vfio_pci_liveupdate_uapi_test

[Vipin Sharma <vipinsh@google.com>]

Add the iommufd_noiommu fixture variant to vfio_pci_liveupdate_uapi_test
and detect at startup whether the target device is bound to vfio-pci in
noiommu mode so that variants not matching the device cleanly skip, in
addition to skipping iommufd variants when probing
luo_session_preserve_fd() in FIXTURE_SETUP reports -ENOENT (e.g. on an
SR-IOV VF or when CONFIG_VFIO_PCI_LIVEUPDATE=n).

When the device is in noiommu mode, verify that preserving its bound
VFIO cdev FD succeeds, and add tests verifying that:
- preserving an unbound second cdev FD fails with -ENOENT without
  affecting the bound FD (preserve_unbound_fd_fails),
- preserving a cdev FD that was never bound fails with -ENOENT
  (preserve_never_bound_fails), and
- closing the Live Update session unpreserves the device so that it can
  be preserved again in a new session (preserve_after_unpreserve).

Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
 .../vfio/vfio_pci_liveupdate_uapi_test.c      | 103 +++++++++++++++++-
 1 file changed, 102 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c b/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c
index da25ea4e2b1e..46e97caf1f54 100644
--- a/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c
+++ b/tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c
@@ -1,10 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
+#include <fcntl.h>
+#include <linux/pci_regs.h>
 #include <libliveupdate.h>
 #include <libvfio.h>
 #include <kselftest_harness.h>
 
 static const char *device_bdf;
+static bool device_is_noiommu;
 
 FIXTURE(vfio_pci_liveupdate_uapi_test) {
 	int luo_fd;
@@ -45,10 +48,19 @@ FIXTURE_VARIANT_ADD(vfio_pci_liveupdate_uapi_test, _iommu_mode) {	\
 }
 
 FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES();
+FIXTURE_VARIANT_ADD_IOMMU_MODE(iommufd_noiommu);
 #undef FIXTURE_VARIANT_ADD_IOMMU_MODE
 
 FIXTURE_SETUP(vfio_pci_liveupdate_uapi_test)
 {
+	bool variant_is_noiommu;
+
+	variant_is_noiommu = !strcmp(variant->iommu_mode, MODE_IOMMUFD_NOIOMMU);
+	if (variant_is_noiommu != device_is_noiommu)
+		SKIP(return, "%s does not apply to a %s device",
+		     variant->iommu_mode,
+		     device_is_noiommu ? "noiommu" : "non-noiommu");
+
 	self->luo_fd = luo_open_device();
 	ASSERT_GT(self->luo_fd, 0);
 
@@ -77,6 +89,7 @@ FIXTURE_TEARDOWN(vfio_pci_liveupdate_uapi_test)
 
 TEST_F(vfio_pci_liveupdate_uapi_test, preserve_device)
 {
+	int expected;
 	int ret;
 
 	ret = luo_session_preserve_fd(self->session_fd, self->device->fd, 0);
@@ -85,7 +98,84 @@ TEST_F(vfio_pci_liveupdate_uapi_test, preserve_device)
 	 * 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);
+	if (device_is_noiommu)
+		expected = 0;
+	else
+		expected = self->iommu->iommufd ? -EOPNOTSUPP : -ENOENT;
+
+	ASSERT_EQ(ret, expected);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_unbound_fd_fails)
+{
+	const char *cdev_path;
+	int unbound_fd;
+	int ret;
+
+	if (!self->iommu->iommufd)
+		SKIP(return, "Only iommufd modes use VFIO cdev files");
+
+	cdev_path = __vfio_pci_get_cdev_path(device_bdf, device_is_noiommu);
+	ASSERT_NE(cdev_path, NULL);
+
+	unbound_fd = open(cdev_path, O_RDWR);
+	ASSERT_GE(unbound_fd, 0);
+	free((void *)cdev_path);
+
+	/*
+	 * A second cdev FD that has not been bound via VFIO_DEVICE_BIND_IOMMUFD
+	 * must be rejected even while another FD for the same device is bound.
+	 */
+	ret = luo_session_preserve_fd(self->session_fd, unbound_fd, 0);
+	ASSERT_EQ(ret, -ENOENT);
+	ASSERT_EQ(close(unbound_fd), 0);
+
+	/* Verify the failed attempt had no side effects on the bound FD. */
+	ret = luo_session_preserve_fd(self->session_fd, self->device->fd, 0);
+	ASSERT_EQ(ret, device_is_noiommu ? 0 : -EOPNOTSUPP);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_never_bound_fails)
+{
+	const char *cdev_path;
+	int unbound_fd;
+	int ret;
+
+	if (!self->iommu->iommufd)
+		SKIP(return, "Only iommufd modes use VFIO cdev files");
+
+	vfio_pci_device_cleanup(self->device);
+	self->device = NULL;
+
+	cdev_path = __vfio_pci_get_cdev_path(device_bdf, device_is_noiommu);
+	ASSERT_NE(cdev_path, NULL);
+
+	unbound_fd = open(cdev_path, O_RDWR);
+	ASSERT_GE(unbound_fd, 0);
+	free((void *)cdev_path);
+
+	ret = luo_session_preserve_fd(self->session_fd, unbound_fd, 0);
+	ASSERT_EQ(ret, -ENOENT);
+	ASSERT_EQ(close(unbound_fd), 0);
+}
+
+TEST_F(vfio_pci_liveupdate_uapi_test, preserve_after_unpreserve)
+{
+	u16 vendor_id;
+
+	if (!device_is_noiommu)
+		SKIP(return, "Only noiommu devices can be preserved");
+
+	ASSERT_EQ(luo_session_preserve_fd(self->session_fd, self->device->fd, 0), 0);
+
+	ASSERT_EQ(close(self->session_fd), 0);
+	self->session_fd = luo_create_session(self->luo_fd, "session2");
+	ASSERT_GT(self->session_fd, 0);
+
+	ASSERT_EQ(luo_session_preserve_fd(self->session_fd, self->device->fd, 0), 0);
+
+	vendor_id = vfio_pci_config_readw(self->device, PCI_VENDOR_ID);
+	ASSERT_NE(vendor_id, 0xffff);
 }
 
 TEST_F(vfio_pci_liveupdate_uapi_test, preserve_group_fails)
@@ -112,6 +202,7 @@ TEST_F(vfio_pci_liveupdate_uapi_test, preserve_container_fails)
 
 int main(int argc, char *argv[])
 {
+	const char *cdev_path;
 	int fd;
 
 	fd = luo_open_device();
@@ -122,5 +213,15 @@ int main(int argc, char *argv[])
 	close(fd);
 
 	device_bdf = vfio_selftests_get_bdf(&argc, argv);
+
+	cdev_path = __vfio_pci_get_cdev_path(device_bdf, true);
+	if (cdev_path) {
+		device_is_noiommu = true;
+	} else {
+		cdev_path = vfio_pci_get_cdev_path(device_bdf);
+		device_is_noiommu = false;
+	}
+	free((void *)cdev_path);
+
 	return test_harness_run(argc, argv);
 }
-- 
2.56.0.317.g454f8302e1-goog