Re: [PATCH v1] pc: Support coldplugging of virtio-pmem-pci devices on all buses

[Vivek Goyal <vgoyal@redhat.com>]

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On Mon, May 25, 2020 at 10:45:11AM +0200, David Hildenbrand wrote:
> E.g., with "pc-q35-4.2", trying to coldplug a virtio-pmem-pci devices
> results in
>     "virtio-pmem-pci not supported on this bus"
> 
> Reasons is, that the bus does not support hotplug and, therefore, does
> not have a hotplug handler. Let's allow coldplugging virtio-pmem devices
> on such buses. The hotplug order is only relevant for virtio-pmem-pci
> when the guest is already alive and the device is visible before
> memory_device_plug() wired up the memory device bits.
> 
> Hotplug attempts will still fail with:
>     "Error: Bus 'pcie.0' does not support hotplugging"
> 
> Hotunplug attempts will still fail with:
>     "Error: Bus 'pcie.0' does not support hotplugging"
> 
> Reported-by: Vivek Goyal <vgoyal@redhat.com>
> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/i386/pc.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)

Thanks for the patch David. I still seem to face a different error though.

2020-05-26T13:26:05.720617Z qemu-system-x86_64: -device virtio-pmem-pci,memdev=pmem1,id=nv1: memory devices (e.g. for memory hotplug) are not enabled, please specify the maxmem option

Following is my domain xml file.

Vivek



[-- Attachment #2: vivek-vm-definition.xml --]
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<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>vm2-f30</name>
  <uuid>c15287f2-9e66-4867-99dc-d77ece6486c8</uuid>
  <metadata>
    <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
      <libosinfo:os id="http://fedoraproject.org/fedora/30"/>
    </libosinfo:libosinfo>
  </metadata>
  <memory unit='KiB'>67108864</memory>
  <currentMemory unit='KiB'>67108864</currentMemory>
  <vcpu placement='static'>64</vcpu>
  <os>
    <type arch='x86_64' machine='pc-q35-4.2'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <vmport state='off'/>
  </features>
  <cpu mode='host-model' check='partial'>
    <model fallback='allow'/>
  </cpu>
  <clock offset='utc'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/vm2-f30.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='sda' bus='sata'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
    </controller>
    <controller type='sata' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pcie-root'/>
    <controller type='pci' index='1' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='1' port='0x10'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/>
    </controller>
    <controller type='pci' index='2' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='2' port='0x11'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/>
    </controller>
    <controller type='pci' index='3' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='3' port='0x12'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/>
    </controller>
    <controller type='pci' index='4' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='4' port='0x13'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x3'/>
    </controller>
    <controller type='pci' index='5' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='5' port='0x14'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x4'/>
    </controller>
    <controller type='pci' index='6' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='6' port='0x15'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/>
    </controller>
    <controller type='pci' index='7' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='7' port='0x16'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x6'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
    </controller>
    <interface type='network'>
      <mac address='52:54:00:51:b6:34'/>
      <source network='default'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <channel type='unix'>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='2'/>
    </channel>
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'>
      <listen type='address'/>
      <image compression='off'/>
    </graphics>
    <sound model='ich9'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
    </sound>
    <video>
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </video>
    <redirdev bus='usb' type='spicevmc'>
      <address type='usb' bus='0' port='2'/>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
      <address type='usb' bus='0' port='3'/>
    </redirdev>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
    </memballoon>
    <rng model='virtio'>
      <backend model='random'>/dev/urandom</backend>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </rng>
  </devices>
  <qemu:commandline>
    <qemu:arg value='-fsdev'/>
    <qemu:arg value='local,id=extra1,path=/mnt/virtio-9p-dir,security_model=none'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='virtio-9p-pci,fsdev=extra1,mount_tag=hostShared'/>
    <qemu:arg value='-object'/>
    <qemu:arg value='memory-backend-file,id=mem,size=64G,mem-path=/dev/shm,share=on'/>
    <qemu:arg value='-numa'/>
    <qemu:arg value='node,memdev=mem'/>
    <qemu:arg value='-chardev'/>
    <qemu:arg value='socket,id=char0,path=/tmp/vhostqemu'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='vhost-user-fs-pci,id=myvirtiofs,chardev=char0,tag=myfs,cache-size=64G,queue-size=1024'/>
    <qemu:arg value='-object'/>
    <qemu:arg value='memory-backend-file,id=pmem1,mem-path=/var/lib/libvirt/images/pmem-vm2-f30.img,share=on,size=4G'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='virtio-pmem-pci,memdev=pmem1,id=nv1'/>
  </qemu:commandline>
</domain>