Avi Kivity wrote:
If a pci device is capable of dma (or issuing interrupts), it will be
useless with pv pci.
Hrm, I think we may be talking about different things. Are you thinking
that the driver I posted allows you to do PCI pass-through over virtio?
That's not what it is.
The driver I posted is a virtio implementation that uses a PCI device.
This lets you use virtio-blk and virtio-net under KVM. The alternative
to this virtio PCI device would be a virtio transport built with
hypercalls like lguest has. I choose a PCI device because it ensured
that each virtio device showed up like a normal PCI device.
Am I misunderstanding what you're asking about?
Regards,
Anthony Liguori
I think that with Amit's pvdma patches you
can support dma-capable devices as well without too much fuss.
What is the use case you're thinking of? A semi-paravirt driver that
does dma directly to a device?
No, an unmodified driver that, by using clever tricks with dma_ops,
can do dma directly to guest memory. See Amit's patches.
In fact, why do a virtio transport at all? It can be done either with
trap'n'emulate, or by directly mapping the device mmio space into the
guest.
(what use case are you considering? devices without interrupts and
dma? pci door stoppers?)
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