On Fri, Jun 24, 2022 at 5:14 PM Michael S. Tsirkin [off-list ref] wrote:

On Tue, Jun 21, 2022 at 06:10:00PM +0200, Ben Hutchings wrote:

quoted

On Tue, 2022-06-21 at 17:34 +0800, Jason Wang wrote:

quoted

On Tue, Jun 21, 2022 at 5:24 PM David Hildenbrand [off-list ref] wrote:

quoted

On 20.06.22 20:49, Ben Hutchings wrote:

quoted

I've tested a 5.19-rc3 kernel on top of QEMU/KVM with machine type
pc-q35-5.2.  It has a virtio balloon device defined in libvirt as:

    <memballoon model="virtio">
      <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
    </memballoon>

but the virtio_balloon driver fails to bind to it:

    virtio_balloon virtio4: init_vqs: add stat_vq failed
    virtio_balloon: probe of virtio4 failed with error -5

Hmm, I don't see any recent changes to drivers/virtio/virtio_balloon.c

virtqueue_add_outbuf() fails with -EIO if I'm not wrong. That's the
first call of virtqueue_add_outbuf() when virtio_balloon initializes.


Maybe something in generic virtio code changed?

Yes, we introduced the IRQ hardening. That could be the root cause and
we've received lots of reports so we decide to disable it by default.

Ben, could you please try this patch: (and make sure
CONFIG_VIRTIO_HARDEN_NOTIFICATION is not set)

https://lore.kernel.org/lkml/20220620024158.2505-1-jasowang@redhat.com/T/ (local)

Yes, that patch fixes the regression for me.

Ben.

Jason are you going to fix balloon to call device_ready before
registering device with linux?

I'm working on the fix, (spot various bugs during review).

Thanks

quoted

--
Ben Hutchings
Any smoothly functioning technology is indistinguishable
from a rigged demo.

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