Linux Virtualization - Aug 2008 - [RFC] [PATCH] SCSI passthrough for virtio-blk

Hi all,

I got bored and implemented SCSI passthrough for the virtio-blk driver.
Principle is quite simple, just put the missing fields (cdb, sense and
status header) on the virtio queue and then call the SG_IO ioctl on the
host.

So when using '-drive file=/dev/sgXX,if=virtio,format=host_device' you
can happily call any sg_XX command on the resulting vdX device. Quite
neat, methinks. And it's even backwards compatible, so each of these
patches should work without the other one applied.

As one would have guessed there are two patches, one for the linux
kernel to modify the virtio-blk driver in the guest and one for the
qemu/kvm userland program to modify the virtio-blk driver on the host.
This patch is relative to avi's kvm-userland tree from kernel.org.

As usual, comments etc to me.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare at suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Markus Rex, HRB 16746 (AG N?rnberg)
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Am Freitag, 29. August 2008 schrieb Hannes Reinecke:
> So when using '-drive file=/dev/sgXX,if=virtio,format=host_device'
you
> can happily call any sg_XX command on the resulting vdX device. Quite
> neat, methinks. And it's even backwards compatible, so each of these
> patches should work without the other one applied.
Does not work here. If the host does not support the pass-through, the device 
drivers waits for an response. I tried  sdparm /dev/vda with a patched kernel 
and an unpatched userspace.

I think you should use a feature bit to avoid problems.

Christian