Re: Mask bit support's API

Michael S. Tsirkin
2010-11-23T16:10:36Z

On Tue, Nov 23, 2010 at 05:24:44PM +0200, Gleb Natapov wrote:
> On Tue, Nov 23, 2010 at 05:11:19PM +0200, Michael S. Tsirkin wrote:
> > On Tue, Nov 23, 2010 at 04:06:20PM +0200, Avi Kivity wrote:
> > > >>
> > > >> So instead of
> > > >>
> > > >> - guest reads/writes msix
> > > >> - kvm filters mmio, implements some, passes others to userspace
> > > >>
> > > >> we have
> > > >>
> > > >> - guest reads/writes msix
> > > >> - kvm implements all
> > > >> - some writes generate an additional notification to userspace
> > > >
> > > >I suppose we don't need to generate notification to userspace? Because every
> > > >read/write is handled by kernel, and userspace just need interface to kernel to
> > > >get/set the entry - and well, does userspace need to do it when kernel can handle
> > > >all of them? Maybe not...
> > >
> > > We could have the kernel handle addr/data writes by setting up an
> > > internal interrupt routing. A disadvantage is that more work is
> > > needed if we emulator interrupt remapping in qemu.
> >
> > As an alternative, interrupt remapping will need some API rework, right?
> > Existing APIs only pass address/data for msi.
> >
> IIRC interrupt remapping works with address/data to. It just interpret
> it differently from apic.

Yes. So since our APIs use address/data, this is an argument for doing
the remapping in kernel.

> --
> Gleb.