On Sun, May 05, 2019 at 05:20:22PM +0800, Peter Xu wrote: > On Sun, May 05, 2019 at 04:56:42PM +0800, Peter Xu wrote: > > When assigning kvm irqfd we didn't check the irqchip mode but we allow > > KVM_IRQFD to succeed with all the irqchip modes. However it does not > > make much sense to create irqfd even without the kernel chips. Let's > > provide a arch-dependent helper to check whether a specific irqfd is > > allowed by the arch. At least for x86, it should make sense to check: > > > > - when irqchip mode is NONE, all irqfds should be disallowed, and, > > > > - when irqchip mode is SPLIT, irqfds that are with resamplefd should > > be disallowed. > > > > For either of the case, previously we'll silently ignore the irq or > > the irq ack event if the irqchip mode is incorrect. However that can > > cause misterious guest behaviors and it can be hard to triage. Let's > > fail KVM_IRQFD even earlier to detect these incorrect configurations. > > > > CC: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > CC: Radim Krčmář <rkrcmar@xxxxxxxxxx> > > CC: Alex Williamson <alex.williamson@xxxxxxxxxx> > > CC: Eduardo Habkost <ehabkost@xxxxxxxxxx> > > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> > > Note: haven't tested, but IIUC QEMU's vfio will naturally fall back to > no-irqfd mode (actually virtio seems to also have this but virtio > should not be affected after all) if the KVM_IRQFD ioctl failed so I > feel like this patch could also at least fix the broken guests > reported besides any future fixes from QEMU side on the issue: > > https://bugs.launchpad.net/qemu/+bug/1826422 Ping - Paolo, should patch still worth to have before the complete fix between split irqchip & resamplefds? Thanks, -- Peter Xu
