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Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus
Thread-Topic: [PATCH 3/5] vDPA: introduce vDPA bus
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Date:   Tue, 21 Jan 2020 14:05:04 +0000
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On Tue, Jan 21, 2020 at 03:15:43AM -0500, Michael S. Tsirkin wrote:
> > This sounds more flexible e.g driver may choose to implement static map=
ping
> > one through commit. But a question here, it looks to me this still requ=
ires
> > the DMA to be synced with at least commit here. Otherwise device may ge=
t DMA
> > fault? Or device is expected to be paused DMA during begin?
> >=20
> > Thanks
>=20
> For example, commit might switch one set of tables for another,
> without need to pause DMA.

I'm not aware of any hardware that can do something like this
completely atomically..

Any mapping change API has to be based around add/remove regions
without any active DMA (ie active DMA is a guest error the guest can
be crashed if it does this)

Jason