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Re: [Qemu-devel] [RFC PATCH 0/4] MSI affinity for assigned devices
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [RFC PATCH 0/4] MSI affinity for assigned devices |
Date: |
Tue, 27 Nov 2012 16:21:02 -0700 |
On Wed, 2012-11-28 at 00:08 +0100, Jan Kiszka wrote:
> On 2012-11-27 23:00, Alex Williamson wrote:
> > This is post-1.3 material, so I'll just post it as an RFC for now.
> >
> > MSI routing updates aren't currently handled by pci-assign or
> > vfio-pci (when using KVM acceleration), which means that trying to
> > set interrupt SMP affinity in the guest has no effect unless MSI is
> > completely disabled and re-enabled. This series fixes this for both
> > device assignment backends using similar schemes. We store the last
> > MSIMessage programmed to KVM and do updates to the MSI route when it
> > changes. pci-assign takes a little bit of refactoring to make this
> > happen cleanly. Thanks,
>
> This should rather be done by implementing vector notifiers for MSI as
> well. That way the device model no longer has to track reasons for
> vector changes in an open-coded fashion, just like we already do for MSI-X.
>
> Was on my todo list for a long time, but I never reached this item.
MSI masking is optional and not many devices seem to support it. What I
see with a linux guest is that it just overwrites the address/data while
MSI is enabled. What were you thinking for notifiers? mask, unmask,
update? I'm not sure I'm interested enough in this to add MSI vector
notifiers. Thanks,
Alex
- [Qemu-devel] [RFC PATCH 0/4] MSI affinity for assigned devices, Alex Williamson, 2012/11/27
- [Qemu-devel] [RFC PATCH 2/4] vfio-pci: Add support for MSI affinity, Alex Williamson, 2012/11/27
- [Qemu-devel] [RFC PATCH 3/4] pci-assign: Refactor MSI virq array, Alex Williamson, 2012/11/27
- [Qemu-devel] [RFC PATCH 4/4] pci-assign: Add MSI affinity support, Alex Williamson, 2012/11/27
- [Qemu-devel] [RFC PATCH 1/4] kvm: Stub kvm_irqchip_update_msi_route, Alex Williamson, 2012/11/27
- Re: [Qemu-devel] [RFC PATCH 0/4] MSI affinity for assigned devices, Jan Kiszka, 2012/11/27
- Re: [Qemu-devel] [RFC PATCH 0/4] MSI affinity for assigned devices,
Alex Williamson <=
- [Qemu-devel] PCI device pass through support, Krishna J, 2012/11/28