Re: [Qemu-devel] [PATCH 00/16] QEMU vhost-scsi support

[Anthony Liguori]

Hi,

As I've mentioned before in the past, I will apply vhost-* without an extremely 
compelling argument for it.

The reason we ultimately settled on vhost-net is that in the absence of a 
fundamental change in the userspace networking interface (with something like VJ 
channels), it's extremely unlikely that we would ever get the right interfaces 
to do zero-copy transmit/receive in userspace.

However, for storage, be it scsi or direct access, the same problem really 
doesn't exist.  There isn't an obvious benefit to being in the kernel.

There are many downsides though.  It's a big security risk.  SCSI is a complex 
protocol and I'd rather the piece of code that's parsing and emulating SCSI cdbs 
was unprivileged and sandboxed than running within the kernel context.

So before we get too deep in patches, we need some solid justification first.

Regards,

Anthony Liguori


On 04/18/2012 09:38 PM, address@hidden wrote:
> From: Zhi Yong Wu<address@hidden>
>
> The patchset was developed originally by Stefan about one year ago. I now 
> rebase it to latest qemu.git/master and fixed some issues to make it work 
> against tcm_vhost and virtio_scsi driver. But there are still some issues to 
> fix. Let us make more effort later.
>
> Stefan Hajnoczi (13):
>    virtio-scsi: Add wwpn and tgpt properties
>    vhost: Pass device path to vhost_dev_init()
>    virtio-scsi: Add vhost_vring_target ioctl struct
>    virtio-scsi: Fix tgpt typo to tpgt and use uint16_t
>    virtio-scsi: Build virtio-scsi.o against vhost.o
>    virtio-scsi: Open and initialize /dev/vhost-scsi
>    virtio-scsi: Start/stop vhost
>    notifier: add validity check and notify function
>    virtio-pci: support host notifiers in TCG mode
>    virtio-pci: check that event notification worked
>    vhost-scsi: add -vhost-scsi host device
>    virtio-scsi: use the vhost-scsi host device
>    virtio-scsi: WIP VHOST_SCSI_SET_ENDPOINT call
>
> Zhi Yong Wu (3):
>    vhost-scsi: enable vhost notifiers for multiple queues
>    vhost-scsi: move some definitions to its header file
>    vhost-scsi: clear endpoint on stopped
>
>   Makefile.target      |    2 +-
>   configure            |    2 +
>   event_notifier.c     |   21 +++++++
>   event_notifier.h     |    4 +
>   hw/qdev-properties.c |   32 ++++++++++
>   hw/qdev.h            |    3 +
>   hw/vhost-scsi.c      |  156 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   hw/vhost-scsi.h      |   39 +++++++++++++
>   hw/vhost.c           |    5 +-
>   hw/vhost.h           |    3 +-
>   hw/vhost_net.c       |    2 +-
>   hw/virtio-pci.c      |   28 ++++++++-
>   hw/virtio-scsi.c     |   52 +++++++++++++++++
>   hw/virtio-scsi.h     |    1 +
>   hw/virtio.c          |    7 ++
>   qemu-common.h        |    1 +
>   qemu-config.c        |   16 +++++
>   qemu-options.hx      |    4 +
>   vl.c                 |   18 ++++++
>   19 files changed, 388 insertions(+), 8 deletions(-)
>   create mode 100644 hw/vhost-scsi.c
>   create mode 100644 hw/vhost-scsi.h