On 23/01/2017 18:04, Michael S. Tsirkin wrote: >> For virtio-blk, my patch moved the setting of ISR from >> virtio_queue_guest_notifier_read to virtio_notify_irqfd. This is >> because the irqfd emulation only needs to trigger the interrupt. >> Setting the ISR should have been done elsewhere. >> >> Can vhost set ISR (I thought it couldn't)? If so, it seems like ARM was >> relying on QEMU's irqfd emulation, as a work around for vhost not >> setting ISR. But this only works if irqfd is directed to QEMU and not >> to KVM. So if vhost cannot set ISR, I think vhost should be disabled >> unless MSI is active. >> >> Am I missing something? > > vhost doesn't set ISR ATM. Without MSI we are always bouncing > interrupts through QEMU in particular in order to set ISR.
Where is the code that disables KVM irqfd? Paolo > Disabling vhost when user requested it was what we did > at some point but this just confused people. > >
