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Re: [PATCH 0/5] vfio/spapr: Handle changes of master irq chip for VFIO d
From: |
Alex Williamson |
Subject: |
Re: [PATCH 0/5] vfio/spapr: Handle changes of master irq chip for VFIO devices |
Date: |
Thu, 21 Nov 2019 18:28:07 -0700 |
On Fri, 22 Nov 2019 12:18:24 +1100
David Gibson <address@hidden> wrote:
> On Thu, Nov 21, 2019 at 09:57:38AM -0700, Alex Williamson wrote:
> > On Thu, 21 Nov 2019 11:56:02 +1100
> > David Gibson <address@hidden> wrote:
> >
> > > Due to the way feature negotiation works in PAPR (which is a
> > > paravirtualized platform), we can end up changing the global irq chip
> > > at runtime, including it's KVM accelerate model. That causes
> > > complications for VFIO devices with INTx, which wire themselves up
> > > directly to the KVM irqchip for performance.
> > >
> > > This series introduces a new notifier to let VFIO devices (and
> > > anything else that needs to in the future) know about changes to the
> > > master irqchip. It modifies VFIO to respond to the notifier,
> > > reconnecting itself to the new KVM irqchip as necessary.
> > >
> > > In particular this removes a misleading (though not wholly inaccurate)
> > > warning that occurs when using VFIO devices on a pseries machine type
> > > guest.
> > >
> > > Open question: should this go into qemu-4.2 or wait until 5.0? It's
> > > has medium complexity / intrusiveness, but it *is* a bugfix that I
> > > can't see a simpler way to fix. It's effectively a regression from
> > > qemu-4.0 to qemu-4.1 (because that introduced XIVE support by
> > > default), although not from 4.1 to 4.2.
> >
> > Looks reasonable to me for 4.2, the vfio changes are not as big as they
> > appear. If Paolo approves this week, I can send a pull request,
> > otherwise I can leave my ack for someone else as I'll be on PTO/holiday
> > next week. Thanks,
>
> I'm happy to take it through my tree, and expect to be sending a PR in
> that timescale, so an ack sounds good.
>
> I've pulled the series into my ppc-for-4.2 branch tentatively.
>
Tested-by: Alex Williamson <address@hidden>
Reviewed-by: Alex Williamson <address@hidden>
Acked-by: Alex Williamson <address@hidden>
- Re: [PATCH 5/5] spapr: Work around spurious warnings from vfio INTx initialization, (continued)
- [PATCH 2/5] vfio/pci: Split vfio_intx_update(), David Gibson, 2019/11/20
- [PATCH 1/5] kvm: Introduce KVM irqchip change notifier, David Gibson, 2019/11/20
- [PATCH 3/5] vfio/pci: Respond to KVM irqchip change notifier, David Gibson, 2019/11/20
- [PATCH 4/5] spapr: Handle irq backend changes with VFIO PCI devices, David Gibson, 2019/11/20
- Re: [PATCH 0/5] vfio/spapr: Handle changes of master irq chip for VFIO devices, Alex Williamson, 2019/11/21
- Re: [PATCH 0/5] vfio/spapr: Handle changes of master irq chip for VFIO devices, Greg Kurz, 2019/11/22