On 2/6/25 11:04 AM, Kirill A. Shutemov wrote: > On Thu, Feb 06, 2025 at 09:59:58AM +0100, Eric Auger wrote: >> Hi, >> >> On 2/4/25 12:46 PM, Eric Auger wrote: >>> Hi, >>> >>> On 2/3/25 3:48 PM, Michael S. Tsirkin wrote: >>>> On Fri, Jan 31, 2025 at 10:53:15AM +0100, Eric Auger wrote: >>>>> 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); >>>> >>>> >>>> I am concerned that full remove is a heavyweight operation. >>>> Do not want to slow down reboots even more. >>>> How about just doing a reset, instead? >>> >>> I tested with >>> >>> static void virtio_dev_shutdown(struct device *_d) >>> { >>> struct virtio_device *dev = dev_to_virtio(_d); >>> >>> virtio_reset_device(dev); >>> } >>> >>> >>> and it fixes my issue. >>> >>> Kirill, would that fix you issue too? >> gentle ping. > > I am on vacation this week. Will try to get around to it next week. OK. Enjoy your vacation! Eric >
