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From: | Paolo Bonzini |
Subject: | Re: [Qemu-devel] Using virtio for inter-VM communication |
Date: | Fri, 13 Jun 2014 10:45:53 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Il 13/06/2014 08:23, Jan Kiszka ha scritto:
That would preserve zero-copy capabilities (as long as you can work against the shared mem directly, e.g. doing DMA from a physical NIC or storage device into it) and keep the hypervisor out of the loop.> > This seems ill thought out. How will you program a NIC via the virtio > protocol without a hypervisor? And how will you make it safe? You'll > need an IOMMU. But if you have an IOMMU you don't need shared memory. Scenarios behind this are things like driver VMs: You pass through the physical hardware to a driver guest that talks to the hardware and relays data via one or more virtual channels to other VMs. This confines a certain set of security and stability risks to the driver VM.
I think implementing Xen hypercalls in jailhouse for grant table and event channels would actually make a lot of sense. The Xen implementation is 2.5kLOC and I think it should be possible to compact it noticeably, especially if you limit yourself to 64-bit guests.
It should also be almost enough to run Xen PVH guests as jailhouse partitions.
If later Xen starts to support virtio, you will get that for free. Paolo
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