Is vHost reversible ?

[Vincent Pelletier <vincent@nexedi.com>]

Hello,

(please keep me CC'ed, I'm not subscribed)

I have a NVMe-like high-performance storage device which requires a
proprietary module to work. Because it is not upstream, I tend to
distrust by default its quality, and I want to isolate it from the rest
of the machine.
I did this by using PCI virtualisation, so now I have a qemu-kvm
running a kernel with the proprietary module, and containing the block
device, and I want to expose this block device back to the host (where
the databases desiring to access this block device will run).

If I ignore the hypervisor/VM relationship, I would be tempted to setup
an iSCSI target over the network, but I am worried about the overhead.

But with this special relationship in mind, I would like to use
vHost-like, just in the exact opposite way (VM has the backstore, host
is the initiator and gets a block device), and likely get a lower
overhead.

Is this possible ?

I am quite new to the whole virtio family, so please forgive me if the
answer is blindingly obvious.
-- 
Vincent Pelletier
ERP5 - open source ERP/CRM for flexible enterprises