kernel/git/stable/linux.git/drivers/vhost/vhost.h, branch master

vhost: invalidate vring access on IOTLB transitions

2026-09-07T22:54:04+00:00

When VIRTIO_F_ACCESS_PLATFORM changes, cached vring pointers and IOTLB metadata are interpreted in a different address space. Keeping them across the transition can leave stale ring mappings in use. Clearing d->iotlb before taking the VQ locks also lets a worker observe a transient NULL d->iotlb and fall back to d->umem while translating a descriptor. Add a common vhost_clear_device_iotlb() helper for vhost-net and vhost-vsock. Take all VQ mutexes in index order before dropping the device-wide IOTLB, invalidate each VQ's cached ring access and metadata, clear pending IOTLB messages, and free the old table after the handoff. This serializes the transition with workers and prevents mixed address space mappings. On the first direct-to-IOTLB transition, invalidate the cached vring addresses. When an existing device IOTLB is replaced, preserve the GIOVA ring addresses and reset only the metadata cache. After clearing ACCESS_PLATFORM, userspace must configure the vring addresses for the new address mode. vhost_vq_invalidate_access() clears desc, avail, and used together. Treat the VQ as invalidated only when all three are NULL, since a single GIOVA address may legitimately be zero. Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") Fixes: e13a6915a03f ("vhost/vsock: add IOTLB API support") Suggested-by: Michael S. Tsirkin Signed-off-by: Jia Jia Signed-off-by: Michael S. Tsirkin Message-ID: <20260828085721.57816-1-physicalmtea@gmail.com>

vhost: limit outstanding IOTLB misses per virtqueue

2026-09-07T22:54:03+00:00

vhost allocates a message node whenever address translation misses. If userspace reads these messages without resolving them, repeated virtqueue kicks can grow the pending message list until the host runs out of memory. Virtqueue processing stops at the first translation miss and cannot make progress until userspace installs a mapping. Keep a pointer to that outstanding message in the virtqueue and suppress additional misses until the node is resolved or discarded. The pointer remains set while the message is queued for reading, copied to userspace, or waiting on the pending list. Clear it under the IOTLB lock when the owning node is freed. This bounds outstanding miss messages by the fixed number of virtqueues without introducing an arbitrary queue limit. Signed-off-by: Linfeng Sun Signed-off-by: Michael S. Tsirkin Message-ID: <20260903-fix-kernel-panic-in-vhost_iotlb_miss_pending_list-v1-1-39b8cd427978@gmail.com>

kcov: refactor common handle ID into kcov_common_handle_id

2026-05-29T04:24:45+00:00

Store common handle IDs in "struct kcov_common_handle_id", which consumes no space in non-KCOV builds. This cleanup removes #ifdef boilerplate code from subsystems that integrate with KCOV (in particular in usbip_common.h and skbuff.h, see the diffstat). This should also make it easier to add KCOV remote coverage to more subsystems in the future. Link: https://lore.kernel.org/20260430-kcov-refactor-common-handle-v1-1-23a0c7a0ba38@google.com Signed-off-by: Jann Horn Acked-by: Greg Kroah-Hartman Reviewed-by: Dmitry Vyukov Acked-by: Jakub Kicinski Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Eugenio Pérez Cc: Hongren (Zenithal) Zheng Cc: Jann Horn Cc: Jason Wang Cc: "Michael S. Tsirkin" Cc: Shuah Khan Cc: Valentina Manea Signed-off-by: Andrew Morton

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2025-12-05T02:59:21+00:00

Pull virtio updates from Michael Tsirkin: "Just a bunch of fixes and cleanups, mostly very simple. Several features were merged through net-next this time around" * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: virtio_pci: drop kernel.h vhost: switch to arrays of feature bits vhost/test: add test specific macro for features virtio: clean up features qword/dword terms vduse: add WQ_PERCPU to alloc_workqueue users virtio_balloon: add WQ_PERCPU to alloc_workqueue users vdpa/pds: use %pe for ERR_PTR() in event handler registration vhost: Fix kthread worker cgroup failure handling virtio: vdpa: Fix reference count leak in octep_sriov_enable() vdpa/mlx5: Fix incorrect error code reporting in query_virtqueues virtio: fix map ops comment virtio: fix virtqueue_set_affinity() docs virtio: standardize Returns documentation style virtio: fix grammar in virtio_map_ops docs virtio: fix grammar in virtio_queue_info docs virtio: fix whitespace in virtio_config_ops virtio: fix typo in virtio_device_ready() comment virtio: fix kernel-doc for mapping/free_coherent functions virtio_vdpa: fix misleading return in void function

vhost: switch to arrays of feature bits

2025-11-30T23:02:43+00:00

The current interface where caller has to know in which 64 bit chunk each bit is, is inelegant and fragile. Let's simply use arrays of bits. By using unroll macros text size grows only slightly. Message-ID: <637e182e139980e5930d50b928ba5ac072d628a9.1764225384.git.mst@redhat.com> Signed-off-by: Michael S. Tsirkin

vhost: rewind next_avail_head while discarding descriptors

2025-11-26T22:44:58+00:00

When discarding descriptors with IN_ORDER, we should rewind next_avail_head otherwise it would run out of sync with last_avail_idx. This would cause driver to report "id X is not a head". Fixing this by returning the number of descriptors that is used for each buffer via vhost_get_vq_desc_n() so caller can use the value while discarding descriptors. Fixes: 67a873df0c41 ("vhost: basic in order support") Cc: stable@vger.kernel.org Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20251120022950.10117-1-jasowang@redhat.com Signed-off-by: Jakub Kicinski

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2025-08-01T21:17:48+00:00

Pull virtio updates from Michael Tsirkin: - vhost can now support legacy threading if enabled in Kconfig - vsock memory allocation strategies for large buffers have been improved, reducing pressure on kmalloc - vhost now supports the in-order feature. guest bits missed the merge window. - fixes, cleanups all over the place * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (30 commits) vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers vsock/virtio: Rename virtio_vsock_skb_rx_put() vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers vsock/virtio: Move SKB allocation lower-bound check to callers vsock/virtio: Rename virtio_vsock_alloc_skb() vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put() vsock/virtio: Validate length in packet header before skb_put() vhost/vsock: Avoid allocating arbitrarily-sized SKBs vhost_net: basic in_order support vhost: basic in order support vhost: fail early when __vhost_add_used() fails vhost: Reintroduce kthread API and add mode selection vdpa: Fix IDR memory leak in VDUSE module exit vdpa/mlx5: Fix release of uninitialized resources on error path vhost-scsi: Fix check for inline_sg_cnt exceeding preallocated limit virtio: virtio_dma_buf: fix missing parameter documentation vhost: Fix typos vhost: vringh: Remove unused functions vhost: vringh: Remove unused iotlb functions ...

vhost: basic in order support

2025-08-01T13:11:09+00:00

This patch adds basic in order support for vhost. Two optimizations are implemented in this patch: 1) Since driver uses descriptor in order, vhost can deduce the next avail ring head by counting the number of descriptors that has been used in next_avail_head. This eliminate the need to access the available ring in vhost. 2) vhost_add_used_and_singal_n() is extended to accept the number of batched buffers per used elem. While this increases the times of userspace memory access but it helps to reduce the chance of used ring access of both the driver and vhost. Vhost-net will be the first user for this. Acked-by: Jonah Palmer Signed-off-by: Jason Wang Message-Id: <20250714084755.11921-3-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin Tested-by: Lei Yang

vhost: Reintroduce kthread API and add mode selection

2025-08-01T13:11:09+00:00

Since commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"), the vhost uses vhost_task and operates as a child of the owner thread. This is required for correct CPU usage accounting, especially when using containers. However, this change has caused confusion for some legacy userspace applications, and we didn't notice until it's too late. Unfortunately, it's too late to revert - we now have userspace depending both on old and new behaviour :( To address the issue, reintroduce kthread mode for vhost workers and provide a configuration to select between kthread and task worker. - Add 'fork_owner' parameter to vhost_dev to let users select kthread or task mode. Default mode is task mode(VHOST_FORK_OWNER_TASK). - Reintroduce kthread mode support: * Bring back the original vhost_worker() implementation, and renamed to vhost_run_work_kthread_list(). * Add cgroup support for the kthread * Introduce struct vhost_worker_ops: - Encapsulates create / stop / wake‑up callbacks. - vhost_worker_create() selects the proper ops according to inherit_owner. - Userspace configuration interface: * New IOCTLs: - VHOST_SET_FORK_FROM_OWNER lets userspace select task mode (VHOST_FORK_OWNER_TASK) or kthread mode (VHOST_FORK_OWNER_KTHREAD) - VHOST_GET_FORK_FROM_OWNER reads the current worker mode * Expose module parameter 'fork_from_owner_default' to allow system administrators to configure the default mode for vhost workers * Kconfig option CONFIG_VHOST_ENABLE_FORK_OWNER_CONTROL controls whether these IOCTLs and the parameter are available - The VHOST_NEW_WORKER functionality requires fork_owner to be set to true, with validation added to ensure proper configuration This partially reverts or improves upon: commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads") commit 1cdaafa1b8b4 ("vhost: replace single worker pointer with xarray") Fixes: 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"), Signed-off-by: Cindy Lu Message-Id: <20250714071333.59794-2-lulu@redhat.com> Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang Tested-by: Lei Yang

vhost-net: allow configuring extended features

2025-07-08T16:05:23+00:00

Use the extended feature type for 'acked_features' and implement two new ioctls operation allowing the user-space to set/query an unbounded amount of features. The actual number of processed features is limited by VIRTIO_FEATURES_MAX and attempts to set features above such limit fail with EOPNOTSUPP. Note that: the legacy ioctls implicitly truncate the negotiated features to the lower 64 bits range and the 'acked_backend_features' field don't need conversion, as the only negotiated feature there is in the low 64 bit range. Acked-by: Jason Wang Signed-off-by: Paolo Abeni