VFIO设备kexec热保留 · v6

从 vfio_pci_core_disable 提取复位逻辑为 vfio_pci_core_try_reset，供 VFIO Liveupdate 复用；disable 改调该 helper，无功能变化。

导出 vfio_device_from_file，并使 vfio_pci_ops 去 static、在头文件声明，供 vfio-pci 模块内 Liveupdate 使用；无功能变化。

导出 liveupdate_register_file_handler 和 unregister，供可模块化的 vfio-pci Liveupdate 文件处理器注册/注销使用。

新增 VFIO_PCI_LIVEUPDATE 与 vfio-pci LUO file handler，注册必需空回调并接入 liveupdate/PCI；先支持 no-iommu，为跨 kexec 保持设备运行铺路。

On Mon, Nov 02, 2026 at 07:36:34AM -0800, Vipin Sharma wrote: > Drivers that keep a device running across Live Update need to hand the > state they captured with pci_store_saved_state() to the next ke

新增 vfio_file_is_bound_cdev 判断绑定 iommufd 的 cdev 文件，并导出 vfio_device_is_noiommu，供 vfio-pci 限定仅 no-iommu 设备可保留。

实现 vfio-pci 的 preserve/freeze 回调：校验 bound cdev 与 no-iommu，将 domain/BDF/config、reset_works、pci_saved_state 序列化到 KHO 保留页，供跨 kexec 保持设备。

新增 vfio_find_device，按 class 条件查找并取 registration 引用，避免仅持 kref 导致模块卸载 UAF；提前初始化 refcount，失败路径等待并发 lookup 排空。

将 vfio_device_fops_cdev_open 拆出静态 helper vfio_device_cdev_open，供后续 Live Update 恢复时重新打开设备文件使用；无功能变化。

提供 VFIO Live Update 恢复用 API，用匿名 inode 创建并返回 cdev 设备文件上下文，重建 kexec 前的 file 状态。

Enable userspace to retrieve preserved VFIO device files after a Live Update by implementing the retrieve() and finish() file handler callbacks. During retrieve(): * Validate the handed-over struct

From: David Matlack dmatlack@google.com Enforce that files for incoming (preserved by previous kernel) VFIO devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD rather than by opening the corre

Protect incoming preserved devices that were kept running across kexec from being disturbed before userspace either claims them or finishes the Live Update session: * Runtime PM idle D3: In vfio_pci

When userspace binds a retrieved VFIO cdev file descriptor via VFIO_DEVICE_BIND_IOMMUFD after kexec, take over the running device in vfio_pci_core_enable() via vfio_pci_liveupdate_take_over() without

From: David Matlack dmatlack@google.com Add documentation for preserving VFIO device files across a Live Update, generated from the kernel-doc comments in the code. Signed-off-by: David Matlack <d

Import and build liveupdate selftest library in VFIO selftests. It allows using liveupdate ioctls in VFIO selftests Co-developed-by: David Matlack dmatlack@google.com Signed-off-by: David Matlack

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. Ensur

Use the given VFIO cdev FD to initialize vfio_pci_device in VFIO selftests. Add the assertion to make sure that passed cdev FD is not used with legacy VFIO APIs. If VFIO cdev FD is provided then do no

From: David Matlack dmatlack@google.com Add Makefile support for TEST_GEN_PROGS_EXTENDED targets. These tests are not run by default. TEST_GEN_PROGS_EXTENDED will be used for Live Update selftests

Add an opt-in iommufd_noiommu mode (MODE_IOMMUFD_NOIOMMU) for devices bound to vfio-pci in noiommu mode. When a device is in noiommu mode, its VFIO character device is named /dev/vfio/devices/noiommu-

Selftest drivers program the IOVA returned by to_iova() into the device. Because a device in noiommu mode uses those addresses directly as physical addresses, DMA buffers must be mapped at IOVA == PA

Add shared libvfio helpers used by the Live Update kexec selftest: - vfio_thp_memfd_alloc() and vfio_memfd_mmap_aligned() to allocate a shmem memfd, map it at a 2MB-aligned virtual address, and b

Add a new attach() op to vfio_pci_driver_ops and a corresponding vfio_pci_driver_attach() wrapper to adopt a device that was already initialized (and optionally has memcpy operations in flight) in ano

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 c

Add a selftest to exercise preserving a vfio-pci device in noiommu mode across a Live Update. For now the test is simple and verifies that the device file can be preserved, retrieved, and bound to iom

Verify that opening a VFIO device through its cdev file and via VFIO_GROUP_GET_DEVICE_FD both fail with -EBUSY if the device was preserved across a Live Update. When a device file is preserved across

Extend vfio_pci_liveupdate_kexec_test to exercise continuous DMA across a Live Update when the device is in noiommu mode. Allocate a shmem memfd backed by three 2MB THP folios (for the driver region,