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vhost-device/crates/scsi
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Viresh Kumar bf75205478 crates: Don't warn for vhost_user::Error::Disconnected 
The vhost_user::Error::Disconnected error code is returned by the
daemon if the VM is shutting down. Don't Warn the user in this case but
just point out that VM may be shutting down.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2023-07-20 13:06:31 +05:30
..
src crates: Don't warn for vhost_user::Error::Disconnected 2023-07-20 13:06:31 +05:30
test scsi: mention out-of-tree fuzzing infrastructure 2023-06-05 14:55:32 +05:30
ARCHITECTURE.md scsi: Add documentation 2023-06-05 14:55:32 +05:30
Cargo.toml tree-wide: drop the Eq trait from Error 2023-07-11 13:30:01 +05:30
CHANGELOG.md Add CHANGELOG.md to all crates 2023-07-07 22:06:45 +05:30
LICENSE-APACHE Symlink license files into crate folders 2023-07-04 14:56:52 +05:30
LICENSE-BSD-3-Clause Symlink license files into crate folders 2023-07-04 14:56:52 +05:30
README.md scsi: Add documentation 2023-06-05 14:55:32 +05:30

README.md

vhost-user-scsi

This is a Rust implementation of a vhost-user-scsi daemon.

Usage

Run the vhost-user-scsi daemon:

vhost-user-scsi -r --socket-path /tmp/vhost-user-scsi.sock /path/to/image.raw /path/to/second-image.raw ...

Run QEMU:

qemu-system-x86_64 ... \
  -device vhost-user-scsi-pci,num_queues=1,param_change=off,chardev=vus \
  -chardev socket,id=vus,path=/tmp/vhost-user-scsi.sock \
  # must match total guest meory
  -object memory-backend-memfd,id=mem,size=384M,share=on \
  -numa node,memdev=mem

Limitations

We are currently only supporting a single request queue and do not support dynamic reconfiguration of LUN parameters (VIRTIO_SCSI_F_CHANGE).

Features

This crate is a work-in-progress. Currently, it's possible to mount and read up to 256 read-only raw disk images. Some features we might like to add at some point, roughly ordered from sooner to later:

  • Write support. This should just be a matter of implementing the WRITE command, but there's a bit of complexity around writeback caching we need to make sure we get right.
  • Support more LUNs. virtio-scsi supports up to 16384 LUNs per target. After 256, the LUN encoding format is different; it's nothing too complicated, but I haven't gotten around to implementing it.
  • Concurrency. Currently, we process SCSI commands one at a time. Eventually, it'd be a good idea to use threads or some fancy async/io_uring stuff to concurrently handle multiple commands. virtio-scsi also allows for multiple request queues, allowing the guest to submit requests from multiple cores in parallel; we should support that.
  • iSCSI passthrough. This shouldn't be too bad, but it might be a good idea to decide on a concurrency model (threads or async) before we spend too much time here.