vfio: selftests: Add helper to set/override a vf_token

Add a helper function, vfio_device_set_vf_token(), to set or override a
vf_token. Not only at init, but a vf_token can also be set via the
VFIO_DEVICE_FEATURE ioctl, by setting the
VFIO_DEVICE_FEATURE_PCI_VF_TOKEN flag. Hence, add an API to utilize this
functionality from the test code. The subsequent commit will use this to
test the functionality of this method to set the vf_token.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Vipin Sharma <vipinsh@google.com>
Tested-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20260505212838.1698034-7-rananta@google.com
Signed-off-by: Alex Williamson <alex@shazbot.org>

2 files changed, 36 insertions, 0 deletions

diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
index 898de032fed5..4ebdc00e20fc 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
@@ -129,4 +129,6 @@ void vfio_container_set_iommu(struct vfio_pci_device *device);
 void vfio_pci_cdev_open(struct vfio_pci_device *device, const char *bdf);
 int __vfio_device_bind_iommufd(int device_fd, int iommufd, const char *vf_token);
 
+void vfio_device_set_vf_token(int fd, const char *vf_token);
+
 #endif /* SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_VFIO_PCI_DEVICE_H */
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index 53e01cdb2b4e..6b855fbcb4a2 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -115,6 +115,40 @@ static void vfio_pci_irq_get(struct vfio_pci_device *device, u32 index,
 	ioctl_assert(device->fd, VFIO_DEVICE_GET_IRQ_INFO, irq_info);
 }
 
+static int vfio_device_feature_ioctl(int fd, u32 flags, void *data,
+				     size_t data_size)
+{
+	u8 buffer[sizeof(struct vfio_device_feature) + data_size] = {};
+	struct vfio_device_feature *feature = (void *)buffer;
+
+	memcpy(feature->data, data, data_size);
+
+	feature->argsz = sizeof(buffer);
+	feature->flags = flags;
+
+	return ioctl(fd, VFIO_DEVICE_FEATURE, feature);
+}
+
+static void vfio_device_feature_set(int fd, u16 feature, void *data, size_t data_size)
+{
+	u32 flags = VFIO_DEVICE_FEATURE_SET | feature;
+	int ret;
+
+	ret = vfio_device_feature_ioctl(fd, flags, data, data_size);
+	VFIO_ASSERT_EQ(ret, 0, "Failed to set feature %u\n", feature);
+}
+
+void vfio_device_set_vf_token(int fd, const char *vf_token)
+{
+	uuid_t token_uuid = {0};
+
+	VFIO_ASSERT_NOT_NULL(vf_token, "vf_token is NULL");
+	VFIO_ASSERT_EQ(uuid_parse(vf_token, token_uuid), 0);
+
+	vfio_device_feature_set(fd, VFIO_DEVICE_FEATURE_PCI_VF_TOKEN,
+				token_uuid, sizeof(uuid_t));
+}
+
 static void vfio_pci_region_get(struct vfio_pci_device *device, int index,
 				struct vfio_region_info *info)
 {