Al Viro said:
"""
Since "vhost/scsi: fix reuse of &vq->iov[out] in response"
we have this:
cmd->tvc_resp_iov = vq->iov[vc.out];
cmd->tvc_in_iovs = vc.in;
combined with
iov_iter_init(&iov_iter, ITER_DEST, &cmd->tvc_resp_iov,
cmd->tvc_in_iovs, sizeof(v_rsp));
in vhost_scsi_complete_cmd_work(). We used to have ->tvc_resp_iov
_pointing_ to vq->iov[vc.out]; back then iov_iter_init() asked to
set an iovec-backed iov_iter over the tail of vq->iov[], with
length being the amount of iovecs in the tail.
Now we have a copy of one element of that array. Fortunately, the members
following it in the containing structure are two non-NULL kernel pointers,
so copy_to_iter() will not copy anything beyond the first iovec - kernel
pointer is not (on the majority of architectures) going to be accepted by
access_ok() in copyout() and it won't be skipped since the "length" (in
reality - another non-NULL kernel pointer) won't be zero.
So it's not going to give a guest-to-qemu escalation, but it's definitely
a bug. Frankly, my preference would be to verify that the very first iovec
is long enough to hold rsp_size. Due to the above, any users that try to
give us vq->iov[vc.out].iov_len < sizeof(struct virtio_scsi_cmd_resp)
would currently get a failure in vhost_scsi_complete_cmd_work()
anyway.
"""
However, the spec doesn't say anything about the legacy descriptor
layout for the respone. So this patch tries to not assume the response
to reside in a single separate descriptor which is what commit
79c14141a487 ("vhost/scsi: Convert completion path to use") tries to
achieve towards to ANY_LAYOUT.
This is done by allocating and using dedicate resp iov in the
command. To be safety, start with UIO_MAXIOV to be consistent with the
limitation that we advertise to the vhost_get_vq_desc().
Testing with the hacked virtio-scsi driver that use 1 descriptor for 1
byte in the response.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Fixes: a77ec83a5789 ("vhost/scsi: fix reuse of &vq->iov[out] in response")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230119073647.76467-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull virtio updates from Michael Tsirkin: - A huge patchset supporting vq resize using the new vq reset capability - Features, fixes, and cleanups all over the place * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (88 commits) vdpa/mlx5: Fix possible uninitialized return value vdpa_sim_blk: add support for discard and write-zeroes vdpa_sim_blk: add support for VIRTIO_BLK_T_FLUSH vdpa_sim_blk: make vdpasim_blk_check_range usable by other requests vdpa_sim_blk: check if sector is 0 for commands other than read or write vdpa_sim: Implement suspend vdpa op vhost-vdpa: uAPI to suspend the device vhost-vdpa: introduce SUSPEND backend feature bit vdpa: Add suspend operation virtio-blk: Avoid use-after-free on suspend/resume virtio_vdpa: support the arg sizes of find_vqs() vhost-vdpa: Call ida_simple_remove() when failed vDPA: fix 'cast to restricted le16' warnings in vdpa.c vDPA: !FEATURES_OK should not block querying device config space vDPA/ifcvf: support userspace to query features and MQ of a management device vDPA/ifcvf: get_config_size should return a value no greater than dev implementation vhost scsi: Allow user to control num virtqueues vhost-scsi: Fix max number of virtqueues vdpa/mlx5: Support different address spaces for control and data vdpa/mlx5: Implement susupend virtqueue callback ...
We are currently hard coded to always create 128 IO virtqueues, so this adds a modparam to control it. For large systems where we are ok with using memory for virtqueues it allows us to add up to 1024. This limit was just selected becuase that's qemu's limit. Signed-off-by: Mike Christie <michael.christie@oracle.com> Message-Id: <20220708030525.5065-3-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com>
Qemu takes it's num_queues limit then adds the fixed queues (control and event) to the total it will request from the kernel. So when a user requests 128 (or qemu does it's num_queues calculation based on vCPUS and other system limits), we hit errors due to userspace trying to setup 130 queues when vhost-scsi has a hard coded limit of 128. This has vhost-scsi adjust it's max so we can do a total of 130 virtqueues (128 IO and 2 fixed). For the case where the user has 128 vCPUs the guest OS can then nicely map each IO virtqueue to a vCPU and not have the odd case where 2 vCPUs share a virtqueue. Signed-off-by: Mike Christie <michael.christie@oracle.com> Message-Id: <20220708030525.5065-2-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com>
Most of the users immediately follow successful iov_iter_get_pages() with advancing by the amount it had returned. Provide inline wrappers doing that, convert trivial open-coded uses of those. BTW, iov_iter_get_pages() never returns more than it had been asked to; such checks in cifs ought to be removed someday... Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch renames vhost_work_dev_flush to just vhost_dev_flush to relfect that it flushes everything on the device and that drivers don't know/care that polls are based on vhost_works. Drivers just flush the entire device and polls, and works for vhost-scsi management TMFs and IO net virtqueues, etc all are flushed. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20220517180850.198915-9-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The flush after vhost_dev_cleanup is not needed because: 1. It doesn't do anything. vhost_dev_cleanup will stop the worker thread so the flush call will just return since the worker has not device. 2. It's not needed for the re-queue case. vhost_scsi_evt_handle_kick grabs the mutex and if the backend is NULL will return without queueing a work. vhost_scsi_clear_endpoint will set the backend to NULL under the vq->mutex then drops the mutex and does a flush. So we know when vhost_scsi_clear_endpoint has dropped the mutex after clearing the backend no evt related work will be able to requeue. The flush would then make sure any queued evts are run and return. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Jason Wang <jasowang@redhat.com> Message-Id: <20220517180850.198915-7-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
use SPDX-License-Identifier instead of a verbose license text Signed-off-by: Cai Huoqing <caihuoqing@baidu.com> Link: https://lore.kernel.org/r/20210821123320.734-1-caihuoqing@baidu.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
vhost_scsi_flush will flush everything, so we can clear the backends then flush, then destroy. We don't need to flush before each vq destruction because after the flush we will have made sure there can be no new cmds started and there are no running cmds. Signed-off-by: Mike Christie <michael.christie@oracle.com> Link: https://lore.kernel.org/r/20210525174733.6212-4-michael.christie@oracle.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com>