kernel/linux.git/drivers/vhost/vhost.c, branch v7.0-rc7

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 '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

vhost: use "checked" versions of get_user() and put_user()

2025-12-26T20:00:01+00:00

vhost_get_user and vhost_put_user leverage __get_user and __put_user, respectively, which were both added in 2016 by commit 6b1e6cc7855b ("vhost: new device IOTLB API"). In a heavy UDP transmit workload on a vhost-net backed tap device, these functions showed up as ~11.6% of samples in a flamegraph of the underlying vhost worker thread. Quoting Linus from [1]: Anyway, every single __get_user() call I looked at looked like historical garbage. [...] End result: I get the feeling that we should just do a global search-and-replace of the __get_user/ __put_user users, replace them with plain get_user/put_user instead, and then fix up any fallout (eg the coco code). Switch to plain get_user/put_user in vhost, which results in a slight throughput speedup. get_user now about ~8.4% of samples in flamegraph. Basic iperf3 test on a Intel 5416S CPU with Ubuntu 25.10 guest: TX: taskset -c 2 iperf3 -c -t 60 -p 5200 -b 0 -u -i 5 RX: taskset -c 2 iperf3 -s -p 5200 -D Before: 6.08 Gbits/sec After: 6.32 Gbits/sec As to what drives the speedup, Sean's patch [2] explains: Use the normal, checked versions for get_user() and put_user() instead of the double-underscore versions that omit range checks, as the checked versions are actually measurably faster on modern CPUs (12%+ on Intel, 25%+ on AMD). The performance hit on the unchecked versions is almost entirely due to the added LFENCE on CPUs where LFENCE is serializing (which is effectively all modern CPUs), which was added by commit 304ec1b05031 ("x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec"). The small optimizations done by commit b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()") likely shave a few cycles off, but the bulk of the extra latency comes from the LFENCE. [1] https://lore.kernel.org/all/CAHk-=wiJiDSPZJTV7z3Q-u4DfLgQTNWqUqqrwSBHp0+Dh016FA@mail.gmail.com/ [2] https://lore.kernel.org/all/20251106210206.221558-1-seanjc@google.com/ Suggested-by: Linus Torvalds Cc: Borislav Petkov Cc: Sean Christopherson Signed-off-by: Jon Kohler Message-Id: <20251113005529.2494066-1-jon@nutanix.com> Acked-by: Jason Wang Signed-off-by: Michael S. Tsirkin

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: Fix kthread worker cgroup failure handling

2025-11-27T07:03:06+00:00

If we fail to attach to a cgroup we are leaking the id. This adds a new goto to free the id. Fixes: 7d9896e9f6d0 ("vhost: Reintroduce kthread API and add mode selection") Signed-off-by: Mike Christie Acked-by: Jason Wang Reviewed-by: Chaitanya Kulkarni Signed-off-by: Michael S. Tsirkin Message-Id: <20251101194358.13605-1-michael.christie@oracle.com>

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

vhost: initialize vq->nheads properly

2025-08-05T09:57:40+00:00

Commit 7918bb2d19c9 ("vhost: basic in order support") introduces vq->nheads to store the number of batched used buffers per used elem but it forgets to initialize the vq->nheads to NULL in vhost_dev_init() this will cause kfree() that would try to free it without be allocated if SET_OWNER is not called. Reported-by: JAEHOON KIM Reported-by: Breno Leitao Fixes: 45347e79b544 ("vhost: basic in order support") Signed-off-by: Jason Wang Message-Id: <20250729073916.80647-1-jasowang@redhat.com> Reviewed-by: Dawid Osuchowski Tested-by: Breno Leitao Reviewed-by: Stefano Garzarella Tested-by: Jaehoon Kim Signed-off-by: Michael S. Tsirkin

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 ...