Re: [libvirt] [PATCH 07/13] qemu: Add hotpluging support for PCI devices on S390 guests

On Mon, 28 May 2018 16:26:57 +0800 Xiao Feng Ren <renxiaof(a)linux.vnet.ibm.com&gt; wrote: > On 5/25/2018 6:22 PM, Bjoern Walk wrote: >> Cornelia Huck <cohuck(a)redhat.com&gt; [2018-05-24, 06:25PM +0200]: >>> On Thu, 24 May 2018 14:24:32 +0200 >>> Xiao Feng Ren <renxiaof(a)linux.vnet.ibm.com&gt; wrote: >>> >>>> From: Yi Min Zhao <zyimin(a)linux.ibm.com&gt; >>>> >>>> This commit adds hotplug support for PCI devices on S390 guests. >>>> There's no need to implement hot unplug for zPCI as QEMU implements >>>> an unplug callback which will unplug both PCI and zPCI device in a >>>> cascaded way. >>>> Currently, the following PCI devices are supported: >>>> virtio-blk-pci >>>> virtio-net-pci >>>> virtio-rng-pci >>>> virtio-input-host-pci >>>> virtio-keyboard-pci >>>> virtio-mouse-pci >>>> virtio-tablet-pci >>>> vfio-pci >>>> Shmem device >>>> SCSIVhost device >>> Hm, how did you arrive at this list? Is it 'anything that uses msi-x'? >> I guess it's just any device that libvirt actually supports hotplug for, >> with a few exceptions (cf. patch 3 and 6). Not familiar wuth msi-x. > The list should be the devices that support MSI-X and have realized the > hotplug in qemu, > we support the hotplug for them in the libvirt.  So the list will be > updated to: > > virtio-blk-pci > virtio-net-pci > virtio-input-host-pci > virtio-keyboard-pci > virtio-mouse-pci > virtio-tablet-pci > vfio-pci > SCSIVhost device Ok, that makes sense. I also checked that libvirt only allows setting the vectors property for virtio-serial and shmem (vectors == 0 turns msi-x off), so that should be fine. > As the model of Shmem is not support in qemu, the rng device doesn't > support MSI-X.  So remove them. So, should qemu add support for msi-x with virtio-rng-pci in the future, we'd want to update libvirt as well, correct? > > In addition, the bug found need to be fixed for the hotplug of tablet, > in the virDomainDeviceIsUSB() > if ((t == VIR_DOMAIN_DEVICE_DISK && >          dev->data.disk->bus == VIR_DOMAIN_DISK_BUS_USB) || >         (t == VIR_DOMAIN_DEVICE_INPUT && >          dev->data.input->type == VIR_DOMAIN_INPUT_BUS_USB) || > ---------->dev->data.input->bus == VIR_DOMAIN_INPUT_BUS_USB >         (t == VIR_DOMAIN_DEVICE_HOSTDEV && > I will send the fix if this bug is agreed. >