On Fri, 30 Apr 2021 15:57:47 +0800 Yicong Yang <yangyicong@xxxxxxxxxxxxx> wrote: > When I try to remove the PF driver in the host, the process will be blocked > if the related VF of the device is added in the Qemu as an iEP. > > here's what I got in the host: > > [root@localhost 0000:75:00.0]# rmmod hisi_zip > [99760.571352] vfio-pci 0000:75:00.1: Relaying device request to user (#0) > [99862.992099] vfio-pci 0000:75:00.1: Relaying device request to user (#10) > [...] > > and in the Qemu: > > estuary:/$ lspci -tv > -[0000:00]-+-00.0 Device 1b36:0008 > +-01.0 Device 1af4:1000 > +-02.0 Device 1af4:1009 > \-03.0 Device 19e5:a251 <----- the related VF device > estuary:/$ qemu-system-aarch64: warning: vfio 0000:75:00.1: Bus 'pcie.0' does not support hotplugging > qemu-system-aarch64: warning: vfio 0000:75:00.1: Bus 'pcie.0' does not support hotplugging > qemu-system-aarch64: warning: vfio 0000:75:00.1: Bus 'pcie.0' does not support hotplugging > qemu-system-aarch64: warning: vfio 0000:75:00.1: Bus 'pcie.0' does not support hotplugging > [...] > > The rmmod process will be blocked until I kill the Qemu process. That's the only way if I > want to end the rmmod. > > So my question is: is such block reasonable? If the VF devcie is occupied or doesn't > support hotplug in the Qemu, shouldn't we fail the rmmod and return something like -EBUSY > rather than make the host blocked indefinitely? Where would we return -EBUSY? pci_driver.remove() returns void. Without blocking, I think our only option would be to kill the user process. > Add the VF under a pcie root port will avoid this. Is it encouraged to always > add the VF under a pcie root port rather than directly add it as an iEP? Releasing a device via the vfio request interrupt is always a cooperative process currently, the VM needs to be configured such that the device is capable of being unplugged and the guest needs to respond to the ejection request. Thanks, Alex
