Re: [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking

Paolo Bonzini
2019-12-17T16:30:53Z

On 17/12/19 17:18, Alex Williamson wrote:
>>
>> Alex, if you are OK we'll work on such interface and move kvmgt to use it.
>> After it's accepted, we can also mark pages dirty through this new interface
>> in Kirti's dirty page tracking series.
> I'm not sure what you're asking for, is it an interface for the host
> CPU to read/write the memory backing of a mapped IOVA range without
> pinning pages? That seems like something like that would make sense for
> an emulation model where a page does not need to be pinned for physical
> DMA. If you're asking more for an interface that understands the
> userspace driver is a VM (ie. implied using a _guest postfix on the
> function name) and knows about GPA mappings beyond the windows directly
> mapped for device access, I'd not look fondly on such a request.

No, it would definitely be the former, using IOVAs to access guest
memory---kvmgt is currently doing the latter by calling into KVM, and
I'm not really fond of that either.

Paolo