Hi Kirill, Michael On 8/8/24 9:51 AM, Kirill A. Shutemov wrote: > Hongyu reported a hang on kexec in a VM. QEMU reported invalid memory > accesses during the hang. > > Invalid read at addr 0x102877002, size 2, region '(null)', reason: rejected > Invalid write at addr 0x102877A44, size 2, region '(null)', reason: rejected > ... > > It was traced down to virtio-console. Kexec works fine if virtio-console > is not in use. > > Looks like virtio-console continues to write to the MMIO even after > underlying virtio-pci device is removed. > > The problem can be mitigated by removing all virtio devices on virtio > bus shutdown. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Reported-by: Hongyu Ning <hongyu.ning@xxxxxxxxxxxxxxx> Gentle ping on that patch that seems to have fallen though the cracks. I think this fix is really needed. I have another test case with a rebooting guest exposed with virtio-net (backed by vhost-net) and viommu. Since there is currently no shutdown for the virtio-net, on reboot, the IOMMU is disabled through the native_machine_shutdown()/ x86_platform.iommu_shutdown() while the virtio-net is still alive. Normally device_shutdown() should call virtio-net shutdown before the IOMMU tear down and we wouldn't see any spurious transactions after iommu shutdown. With that fix, the above test case is fixed and I do not see spurious vhost IOTLB miss spurious requests. For more details, see qemu thread ([PATCH] hw/virtio/vhost: Disable IOTLB callbacks when IOMMU gets disabled, https://lore.kernel.org/all/20250120173339.865681-1-eric.auger@xxxxxxxxxx/) Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> Tested-by: Eric Auger <eric.auger@xxxxxxxxxx> Thanks Eric > --- > drivers/virtio/virtio.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index a9b93e99c23a..6c2f908eb22c 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -356,6 +356,15 @@ static void virtio_dev_remove(struct device *_d) > of_node_put(dev->dev.of_node); > } > > +static void virtio_dev_shutdown(struct device *_d) > +{ > + struct virtio_device *dev = dev_to_virtio(_d); > + struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); > + > + if (drv && drv->remove) > + drv->remove(dev); > +} > + > static const struct bus_type virtio_bus = { > .name = "virtio", > .match = virtio_dev_match, > @@ -363,6 +372,7 @@ static const struct bus_type virtio_bus = { > .uevent = virtio_uevent, > .probe = virtio_dev_probe, > .remove = virtio_dev_remove, > + .shutdown = virtio_dev_shutdown, > }; > > int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)
