On Thu, 21 Nov 2019 11:56:02 +1100 David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> 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, Alex > Changes since RFC: > * Fixed some incorrect error paths pointed by aw in 3/5 > * 5/5 had some problems previously, but they have been obsoleted by > other changes merged in the meantime > > David Gibson (5): > kvm: Introduce KVM irqchip change notifier > vfio/pci: Split vfio_intx_update() > vfio/pci: Respond to KVM irqchip change notifier > spapr: Handle irq backend changes with VFIO PCI devices > spapr: Work around spurious warnings from vfio INTx initialization > > accel/kvm/kvm-all.c | 18 ++++++++++++ > accel/stubs/kvm-stub.c | 12 ++++++++ > hw/ppc/spapr_irq.c | 17 +++++++++++- > hw/vfio/pci.c | 62 +++++++++++++++++++++++++++--------------- > hw/vfio/pci.h | 1 + > include/sysemu/kvm.h | 5 ++++ > 6 files changed, 92 insertions(+), 23 deletions(-) >
