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Filename Latest commit message Latest commit date
Gavin Shan 5fd4f81421 vhost: Add smp_rmb() in vhost_vq_avail_empty()
commit 22e1992cf7b034db5325660e98c41ca5afa5f519 upstream.

A smp_rmb() has been missed in vhost_vq_avail_empty(), spotted by
Will. Otherwise, it's not ensured the available ring entries pushed
by guest can be observed by vhost in time, leading to stale available
ring entries fetched by vhost in vhost_get_vq_desc(), as reported by
Yihuang Yu on NVidia's grace-hopper (ARM64) platform.

  /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64      \
  -accel kvm -machine virt,gic-version=host -cpu host          \
  -smp maxcpus=1,cpus=1,sockets=1,clusters=1,cores=1,threads=1 \
  -m 4096M,slots=16,maxmem=64G                                 \
  -object memory-backend-ram,id=mem0,size=4096M                \
   :                                                           \
  -netdev tap,id=vnet0,vhost=true                              \
  -device virtio-net-pci,bus=pcie.8,netdev=vnet0,mac=52:54:00:f1:26:b0
   :
  guest# netperf -H 10.26.1.81 -l 60 -C -c -t UDP_STREAM
  virtio_net virtio0: output.0:id 100 is not a head!

Add the missed smp_rmb() in vhost_vq_avail_empty(). When tx_can_batch()
returns true, it means there's still pending tx buffers. Since it might
read indices, so it still can bypass the smp_rmb() in vhost_get_vq_desc().
Note that it should be safe until vq->avail_idx is changed by commit
275bf960ac ("vhost: better detection of available buffers").

Fixes: 275bf960ac ("vhost: better detection of available buffers")
Cc: <stable@kernel.org> # v4.11+
Reported-by: Yihuang Yu <yihyu@redhat.com>
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20240328002149.1141302-2-gshan@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-05-02 16:18:29 +02:00
arch x86/alternative: Don't call text_poke() in lazy TLB mode 2024-04-13 12:51:40 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 12:51:38 +02:00
certs
crypto crypto: api - Disallow identical driver names 2024-02-23 08:24:48 +01:00
Documentation x86/cpu: Enable STIBP on AMD if Automatic IBRS is enabled 2024-04-13 12:51:32 +02:00
drivers vhost: Add smp_rmb() in vhost_vq_avail_empty() 2024-05-02 16:18:29 +02:00
fs btrfs: qgroup: correctly model root qgroup rsv in convert 2024-05-02 16:18:29 +02:00
include af_unix: Do not use atomic ops for unix_sk(sk)->inflight. 2024-05-02 16:18:29 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:51:36 +02:00
ipc
kernel panic: Flush kernel log buffer at the end 2024-04-13 12:51:37 +02:00
lib net: blackhole_dev: fix build warning for ethh set but not used 2024-03-26 18:22:15 -04:00
LICENSES
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-13 12:51:40 +02:00
net af_unix: Fix garbage collector racing against connect() 2024-05-02 16:18:29 +02:00
samples media: rename VFL_TYPE_GRABBER to _VIDEO 2024-03-26 18:22:22 -04:00
scripts kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1 2024-04-13 12:51:26 +02:00
security smack: Handle SMACK64TRANSMUTE in smack_inode_setsecurity() 2024-04-13 12:51:22 +02:00
sound ALSA: hda/realtek: Update Panasonic CF-SZ6 quirk to support headset with microphone 2024-04-13 12:51:36 +02:00
tools tools: iio: replace seekdir() in iio_generic_buffer 2024-04-13 12:51:39 +02:00
usr
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-13 12:51:22 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.274 2024-04-13 12:51:41 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.