Re: [PATCH v3 00/12] KVM: Add host swap event notifications for PV guest

[Rik van Riel]

On 01/05/2010 10:05 AM, Jun Koi wrote:
> On Tue, Jan 5, 2010 at 11:12 PM, Gleb Natapov<gleb@xxxxxxxxxx>  wrote:
> > KVM virtualizes guest memory by means of shadow pages or HW assistance
> > like NPT/EPT. Not all memory used by a guest is mapped into the guest
> > address space or even present in a host memory at any given time.
> > When vcpu tries to access memory page that is not mapped into the guest
> > address space KVM is notified about it. KVM maps the page into the guest
> > address space and resumes vcpu execution. If the page is swapped out
> > from host memory vcpu execution is suspended till the page is not swapped
> > into the memory again. This is inefficient since vcpu can do other work
> > (run other task or serve interrupts) while page gets swapped in.
> >
> > To overcome this inefficiency this patch series implements "asynchronous
> > page fault" for paravirtualized KVM guests. If a page that vcpu is
> > trying to access is swapped out KVM sends an async PF to the vcpu
> > and continues vcpu execution. Requested page is swapped in by another
> > thread in parallel.  When vcpu gets async PF it puts faulted task to
> > sleep until "wake up" interrupt is delivered. When the page is brought
> > to the host memory KVM sends "wake up" interrupt and the guest's task
> > resumes execution.
>
> Is it true that to make this work, we will need a (PV) kernel driver
> for each guest OS (Windows, Linux, ...)?

This patch series contains the guest kernel code for Linux,
as well as the host side code.

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