Re: [PULL v3 12/55] virtio-pci: add support for configure interrupt

[Volker Rümelin]

Hi,

> From: Cindy Lu <lulu@redhat.com>
>
> Add support for configure interrupt, The process is used kvm_irqfd_assign
> to set the gsi to kernel. When the configure notifier was signal by
> host, qemu will inject a msix interrupt to guest
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> Message-Id: <20211104164827.21911-11-lulu@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>   hw/virtio/virtio-pci.h |  4 +-
>   hw/virtio/virtio-pci.c | 92 ++++++++++++++++++++++++++++++++++++------
>   2 files changed, 83 insertions(+), 13 deletions(-)

Since this commit I see the following warnings.

With -drive 
if=virtio,id=disk1,file=/srv/cdimg/Linux/images/opensuse.qcow2,discard=unmap

qemu-system-x86_64: virtio-blk failed to set guest notifier (-16), 
ensure -accel kvm is set.
qemu-system-x86_64: virtio_bus_start_ioeventfd: failed. Fallback to 
userspace (slower).

With libvirt
    <controller type='pci' index='1' model='pcie-root-port'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1c' 
function='0'
       multifunction='on'/>
    </controller>
    <controller type='pci' index='2' model='pcie-root-port'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1c' 
function='1'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver queues='4'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' 
function='0'/>
    </controller>
    <disk type='block' device='disk'>
      <driver name='qemu' type='raw' cache='none' discard='unmap' 
io='io_uring'/>
      <source dev='/dev/vgtmp/lnxpowerm1'/>
      <target dev='sda' bus='scsi'/>
      <address type='drive' controller='0' bus='0' unit='0'/>
      <boot order='1'/>
    </disk>

2022-01-08T17:45:26.911491Z qemu-system-x86_64: virtio-scsi: Failed to 
set guest notifiers (-16), ensure -accel kvm is set.
2022-01-08T17:45:26.911505Z qemu-system-x86_64: 
virtio_bus_start_ioeventfd: failed. Fallback to userspace (slower).

The messages appear around the time the Linux guest initializes the drivers.

With best regards,
Volker