linux-stable.git/drivers/vhost, branch v6.5.2

vhost-scsi: Rename vhost_scsi_iov_to_sgl

2023-08-10T19:24:28+00:00

Rename vhost_scsi_iov_to_sgl to vhost_scsi_map_iov_to_sgl so it matches
matches the naming style used for vhost_scsi_copy_iov_to_sgl.

Signed-off-by: Mike Christie 
Message-Id: <20230709202859.138387-3-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin 
Acked-by: Stefan Hajnoczi

vhost-scsi: Fix alignment handling with windows

2023-08-10T19:24:27+00:00

The linux block layer requires bios/requests to have lengths with a 512
byte alignment. Some drivers/layers like dm-crypt and the directi IO code
will test for it and just fail. Other drivers like SCSI just assume the
requirement is met and will end up in infinte retry loops. The problem
for drivers like SCSI is that it uses functions like blk_rq_cur_sectors
and blk_rq_sectors which divide the request's length by 512. If there's
lefovers then it just gets dropped. But other code in the block/scsi
layer may use blk_rq_bytes/blk_rq_cur_bytes and end up thinking there is
still data left and try to retry the cmd. We can then end up getting
stuck in retry loops where part of the block/scsi thinks there is data
left, but other parts think we want to do IOs of zero length.

Linux will always check for alignment, but windows will not. When
vhost-scsi then translates the iovec it gets from a windows guest to a
scatterlist, we can end up with sg items where the sg->length is not
divisible by 512 due to the misaligned offset:

sg[0].offset = 255;
sg[0].length = 3841;
sg...
sg[N].offset = 0;
sg[N].length = 255;

When the lio backends then convert the SG to bios or other iovecs, we
end up sending them with the same misaligned values and can hit the
issues above.

This just has us drop down to allocating a temp page and copying the data
when we detect a misaligned buffer and the IO is large enough that it
will get split into multiple bad IOs.

Signed-off-by: Mike Christie 
Message-Id: <20230709202859.138387-2-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin 
Acked-by: Stefan Hajnoczi

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

2023-07-03T22:38:26+00:00

Pull virtio updates from Michael Tsirkin:

 - resume support in vdpa/solidrun

 - structure size optimizations in virtio_pci

 - new pds_vdpa driver

 - immediate initialization mechanism for vdpa/ifcvf

 - interrupt bypass for vdpa/mlx5

 - multiple worker support for vhost

 - viirtio net in Intel F2000X-PL support for vdpa/ifcvf

 - fixes, cleanups all over the place

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (48 commits)
  vhost: Make parameter name match of vhost_get_vq_desc()
  vduse: fix NULL pointer dereference
  vhost: Allow worker switching while work is queueing
  vhost_scsi: add support for worker ioctls
  vhost: allow userspace to create workers
  vhost: replace single worker pointer with xarray
  vhost: add helper to parse userspace vring state/file
  vhost: remove vhost_work_queue
  vhost_scsi: flush IO vqs then send TMF rsp
  vhost_scsi: convert to vhost_vq_work_queue
  vhost_scsi: make SCSI cmd completion per vq
  vhost_sock: convert to vhost_vq_work_queue
  vhost: convert poll work to be vq based
  vhost: take worker or vq for flushing
  vhost: take worker or vq instead of dev for queueing
  vhost, vhost_net: add helper to check if vq has work
  vhost: add vhost_worker pointer to vhost_virtqueue
  vhost: dynamically allocate vhost_worker
  vhost: create worker at end of vhost_dev_set_owner
  virtio_bt: call scheduler when we free unused buffs
  ...

vhost: Make parameter name match of vhost_get_vq_desc()

2023-07-03T16:15:15+00:00

The parameter name in the function declaration and definition
should be the same.

drivers/vhost/vhost.h,
int vhost_get_vq_desc(..., unsigned int iov_count,...);

drivers/vhost/vhost.c,
int vhost_get_vq_desc(..., unsigned int iov_size,...)

Signed-off-by: Xianting Tian 
Message-Id: <20230621093835.36878-1-xianting.tian@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin

vhost: Allow worker switching while work is queueing

2023-07-03T16:15:14+00:00

This patch drops the requirement that we can only switch workers if work
has not been queued by using RCU for the vq based queueing paths and a
mutex for the device wide flush.

We can also use this to support SIGKILL properly in the future where we
should exit almost immediately after getting that signal. With this
patch, when get_signal returns true, we can set the vq->worker to NULL
and do a synchronize_rcu to prevent new work from being queued to the
vhost_task that has been killed.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-18-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin

vhost_scsi: add support for worker ioctls

2023-07-03T16:15:14+00:00

This has vhost-scsi support the worker ioctls by calling the
vhost_worker_ioctl helper.

With a single worker, the single thread becomes a bottlneck when trying
to use 3 or more virtqueues like:

fio --filename=/dev/sdb  --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=128  --numjobs=3

With the patches and doing a worker per vq, we can scale to at least
16 vCPUs/vqs (that's my system limit) with the same command fio command
above with numjobs=16:

fio --filename=/dev/sdb  --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=64  --numjobs=16

which gives around 2002K IOPs.

Note that for testing I dropped depth to 64 above because the vhost/virt
layer supports only 1024 total commands per device. And the only tuning I
did was set LIO's emulate_pr to 0 to avoid LIO's PR lock in the main IO
path which becomes an issue at around 12 jobs/virtqueues.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-17-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin

vhost: allow userspace to create workers

2023-07-03T16:15:14+00:00

For vhost-scsi with 3 vqs or more and a workload that tries to use
them in parallel like:

fio --filename=/dev/sdb  --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=128  --numjobs=3

the single vhost worker thread will become a bottlneck and we are stuck
at around 500K IOPs no matter how many jobs, virtqueues, and CPUs are
used.

To better utilize virtqueues and available CPUs, this patch allows
userspace to create workers and bind them to vqs. You can have N workers
per dev and also share N workers with M vqs on that dev.

This patch adds the interface related code and the next patch will hook
vhost-scsi into it. The patches do not try to hook net and vsock into
the interface because:

1. multiple workers don't seem to help vsock. The problem is that with
only 2 virtqueues we never fully use the existing worker when doing
bidirectional tests. This seems to match vhost-scsi where we don't see
the worker as a bottleneck until 3 virtqueues are used.

2. net already has a way to use multiple workers.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-16-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin

vhost: replace single worker pointer with xarray

2023-07-03T16:15:14+00:00

The next patch allows userspace to create multiple workers per device,
so this patch replaces the vhost_worker pointer with an xarray so we
can store mupltiple workers and look them up.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-15-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin

vhost: add helper to parse userspace vring state/file

2023-07-03T16:15:14+00:00

The next patches add new vhost worker ioctls which will need to get a
vhost_virtqueue from a userspace struct which specifies the vq's index.
This moves the vhost_vring_ioctl code to do this to a helper so it can
be shared.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-14-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin

vhost: remove vhost_work_queue

2023-07-03T16:15:14+00:00

vhost_work_queue is no longer used. Each driver is using the poll or vq
based queueing, so remove vhost_work_queue.

Signed-off-by: Mike Christie 
Message-Id: <20230626232307.97930-13-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin