> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Alex Williamson > Sent: Thursday, November 13, 2014 1:11 AM > To: Paolo Bonzini > Cc: Zhang, Yang Z; Wu, Feng; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; eric.auger > Subject: Re: [PATCH 05/13] KVM: Update IRTE according to guest interrupt > configuration changes > > On Wed, 2014-11-12 at 10:14 +0100, Paolo Bonzini wrote: > > > > On 12/11/2014 04:42, Zhang, Yang Z wrote: > > > Personally, I think this feature will be helpful to the legacy device > > > assignment. Agree, vfio is the right solution for future feature > > > enabling. But the old kvm without the good vfio supporting is still > > > used largely today. The user really looking for this feature but they > > > will not upgrade their kernel. It's easy for us to backport this > > > feature to old kvm with the legacy device assignment, but it is > > > impossible to backport the whole vfio. > > > > You can certainly backport these patches to distros that do not have > > VFIO. But upstream we should work on VFIO first. VFIO has feature > > parity with legacy device assignment, and adding a new feature that is > > not in VFIO would be a bad idea. > > Thanks Paolo, I agree. We should design the interfaces for VFIO since > we expect legacy KVM assignment to be deprecated and eventually removed. > I think that some of the platform device work for ARM's IRQ forwarding > should probably be leveraged for this interface. IRQ forwarding > effectively allows level triggered interrupts to be handled as edge, > eliminating the mask/unmask overhead and EOI path entirely. To do this > through VFIO they make use of the KVM-VFIO device to register the device > and set attributes for the forwarded IRQ. This enables KVM to use the > VFIO external user interfaces to acquire a VFIO device reference and > access the struct device. From there it can do some IRQ manipulation on > the device to reconfigure how the host handles the interrupt. Ideally > we could use the same base KVM-VFIO device interface interface, perhaps > with different attributes, and obviously with different architecture > backing. Thanks, > > Alex >
I think to enable VT-d PI in VFIO framework, most of the code in the current patch can remain unchanged. Except that we need to find a way to update the IRTE of the assigned device's host irq when the guest is updating MSI/MSI-x configuration. Alex and Paolo, since we are not familiar with VFIO, It would be highly appreciated if you can give more help on VFIO side for this feature? Thanks, Feng > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
