kernel/git/stable/linux.git/drivers/vhost/vhost.c, 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>

vhost: reject zero-size IOTLB INVALIDATE

2026-08-19T10:38:47+00:00

Reject VHOST_IOTLB_INVALIDATE messages with size == 0 to prevent iova + size - 1 from underflowing to U64_MAX, which would incorrectly delete the entire IOTLB. Signed-off-by: xiongweimin Signed-off-by: Michael S. Tsirkin Message-ID: <20260716030236.124322-1-xiongwm2026@163.com>

vhost: reset the vring metadata cache on vring reconfiguration

2026-08-04T03:08:15+00:00

vq->meta_iotlb[] caches the vhost_iotlb_map that backs each vring metadata region, and iotlb_access_ok() returns early on a cache hit, taking the hit as proof that the region has already been validated: if (vhost_vq_meta_fetch(vq, addr, len, type)) return true; The cache is reset on VHOST_IOTLB_UPDATE and VHOST_IOTLB_INVALIDATE, on device IOTLB (re)initialisation and on vq reset, but not when VHOST_SET_VRING_ADDR replaces vq->desc, vq->avail and vq->used, nor when VHOST_SET_VRING_NUM changes the region sizes. With a device IOTLB attached both ioctls are accepted while the vq is live, and neither validates the addresses at ioctl time: vq_access_ok() and vq_log_used_access_ok() return true early because the addresses are GIOVAs, deferring validation to prefetch time. Once the cache has been populated that deferred validation no longer runs -- vq_meta_prefetch() hits the stale entry and returns true -- and vhost_vq_meta_fetch() keeps translating through the old mapping as map->addr + addr - map->start for an address the mapping no longer covers. vhost_copy_to_user() and vhost_copy_from_user() consume the result with __copy_to_user() and __copy_from_user(), which do not check it either, so a subsequent used ring update or descriptor fetch accesses memory outside the region the IOTLB actually maps. Reset the metadata cache whenever the vring is reconfigured, so the new addresses are pushed back through iotlb_access_ok()'s slow path. Fixes: f88949138058 ("vhost: introduce O(1) vq metadata cache") Cc: stable@vger.kernel.org Assisted-by: tencentos-corvus-ai:kimi-k3 Signed-off-by: Jun Yang Message-ID: <20260803014823.68623-1-juny24602@gmail.com> Signed-off-by: Michael S. Tsirkin

vhost_iotlb: bound map allocation in add_range

2026-08-03T19:21:54+00:00

vhost_iotlb_add_range_ctx() only retires an old entry when the table has a non-zero limit, has exactly reached that limit and has VHOST_IOTLB_FLAG_RETIRE set. Non-retiring tables can keep allocating entries after reaching their configured limit. Existing vhost devices allocate their IOTLB with max_iotlb_entries from vhost.c, which defaults to 2048 and is tunable by module parameter. Use the caller-provided limit at the allocation point instead of adding a separate default in the common IOTLB helper, and reject non-positive values in vhost paths that can report an error. Other vhost IOTLB users should not create zero-limit tables when entries can be populated from userspace or guest-controlled requests. Add caller-side max_iotlb_entries parameters for mlx5 vDPA, VDUSE and vhost-vDPA. Reject non-positive VDUSE and vhost-vDPA values, and require at least two entries for vdpa_sim and mlx5 vDPA paths that install full-range mappings, since those mappings are split into two IOTLB entries. Handle full-range mappings in the common helper by checking that the IOTLB can hold both split entries before inserting the first half. This avoids returning an error after leaving a half mapping behind. When the table is full, keep the existing retire behavior for retiring tables and return -ENOSPC for non-retiring tables. Reuse the retired map node instead of freeing it and allocating a replacement, so a stream of IOTLB updates cannot keep forcing GFP_ATOMIC allocations after the table has reached its limit. If a zero-limit IOTLB still reaches the common helper, treat it as a configuration error and return -EINVAL. I found this bug myself, though the patch was written with AI assistance. Fixes: 0bbe30668d89 ("vhost: factor out IOTLB") Assisted-by: OpenAI-Codex:GPT-5 Signed-off-by: Linfeng Sun Message-ID: Signed-off-by: Michael S. Tsirkin

vhost: remove unnecessary module_init/exit functions

2026-06-10T06:17:00+00:00

The vhost driver has unnecessary empty module_init and module_exit functions. Remove them. Note that if a module_init function exists, a module_exit function must also exist; otherwise, the module cannot be unloaded. Signed-off-by: Ethan Nelson-Moore Signed-off-by: Michael S. Tsirkin Message-ID: <20260131020010.45647-1-enelsonmoore@gmail.com>

vhost: fix vhost_get_avail_idx for a non empty ring

2026-06-04T04:25:54+00:00

vhost_get_avail_idx is supposed to report whether it has updated vq->avail_idx. Instead, it returns whether all entries have been consumed, which is usually the same. But not always - in drivers/vhost/net.c and when mergeable buffers have been enabled, the driver checks whether the combined entries are big enough to store an incoming packet. If not, the driver re-enables notifications with available entries still in the ring. The incorrect return value from vhost_get_avail_idx propagates through vhost_enable_notify and causes the host to livelock if the guest is not making progress, as vhost will immediately disable notifications and retry using the available entries. This goes back to commit d3bb267bbdcb ("vhost: cache avail index in vhost_enable_notify()") which changed vhost_enable_notify() to compare the freshly read avail index against vq->last_avail_idx instead of the previously cached vq->avail_idx. Commit 7ad472397667 ("vhost: move smp_rmb() into vhost_get_avail_idx()") then carried over the same comparison when refactoring vhost_enable_notify() to call the unified vhost_get_avail_idx(). The obvious fix is to make vhost_get_avail_idx do what the comment says it does and report whether new entries have been added. Reported-by: ShuangYu Fixes: d3bb267bbdcb ("vhost: cache avail index in vhost_enable_notify()") Cc: Stefan Hajnoczi Acked-by: Jason Wang Reviewed-by: Stefano Garzarella Signed-off-by: Michael S. Tsirkin Message-Id: <559b04ae6ce52973c535dc47e461638b7f4c3d63.1772441455.git.mst@redhat.com>

Convert more 'alloc_obj' cases to default GFP_KERNEL arguments

2026-02-22T04:03:00+00:00

This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\