Using the KVM API [LWN.net]

Using the KVM API

Posted Oct 1, 2015 7:17 UTC (Thu) by pbonzini (subscriber, #60935)
In reply to: Using the KVM API by josh
Parent article: Using the KVM API

It's about 50-50.

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Using the KVM API

Posted Oct 1, 2015 15:50 UTC (Thu) by josh (subscriber, #17465) [Link] (1 responses)

Ouch. That really limits how much faster it can get, then, short of implementing the backend in the kernel.

Using the KVM API

Posted Oct 1, 2015 16:02 UTC (Thu) by pbonzini (subscriber, #60935) [Link]

Even if you implement in the kernel, it's hard to bypass all the stuff that KVM does at vmexit. The processor doesn't restore the whole host state at vmexit time, but KVM must restore at least whatever is needed to run Linux (e.g. the %fs base to access per_cpu variables).