Gavin Shan 22e1992cf7 vhost: Add smp_rmb() in vhost_vq_avail_empty() ... 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>		2024-04-08 04:11:04 -04:00
..
iotlb.c	vhost_iotlb: split out IOTLB initialization	2022-05-31 12:44:28 -04:00
Kconfig	vhost_task: Allow vhost layer to use copy_process	2023-03-23 12:45:36 +01:00
Makefile	vhost: introduce vDPA-based backend	2020-04-02 10:41:40 -04:00
net.c	virtio: features, fixes	2024-03-19 08:57:39 -07:00
scsi.c	vhost,virtio,vdpa: features, fixes, cleanups	2023-11-05 09:02:32 -10:00
test.c	vhost-test: remove meaningless debug info	2023-02-20 19:26:58 -05:00
test.h	tools/virtio: Add --reset	2020-06-22 12:34:21 -04:00
vdpa.c	vDPA: introduce get_vq_size to vdpa_config_ops	2024-03-19 02:45:50 -04:00
vhost.c	vhost: Add smp_rmb() in vhost_vq_avail_empty()	2024-04-08 04:11:04 -04:00
vhost.h	eventfd: simplify eventfd_signal()	2023-11-28 14:08:38 +01:00
vringh.c	vringh: don't use vringh_kiov_advance() in vringh_iov_xfer()	2023-10-04 08:26:48 +01:00
vsock.c	virtio/vsock: send credit update during setting SO_RCVLOWAT	2023-12-15 10:37:35 +00:00