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Re: [Qemu-devel] [PATCH v2] vhost: Update 'ioeventfd_started' with host

From: Alexey Kardashevskiy
Subject: Re: [Qemu-devel] [PATCH v2] vhost: Update 'ioeventfd_started' with host notifiers
Date: Thu, 17 Nov 2016 16:23:48 +1100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0

On 16/11/16 19:38, Felipe Franciosi wrote:
>> On 16 Nov 2016, at 04:05, Alexey Kardashevskiy <address@hidden> wrote:
>> On 11/11/16 01:45, Christian Borntraeger wrote:
>>> On 11/09/2016 01:44 PM, Felipe Franciosi wrote:
>>>> Following the recent refactor of virtio notfiers [1], more specifically
>>>> the patch that uses virtio_bus_set_host_notifier [2] by default, core
>>>> virtio code requires 'ioeventfd_started' to be set to true/false when
>>>> the host notifiers are configured. Because not all vhost devices were
>>>> update (eg. vhost-scsi) to use the new interface, this value is always
>>>> set to false.
>>>> When booting a guest with a vhost-scsi backend controller, SeaBIOS will
>>>> initially configure the device which sets all notifiers. The guest will
>>>> continue to boot fine until the kernel virtio-scsi driver reinitialises
>>>> the device causing a stop followed by another start. Since
>>>> ioeventfd_started was never set to true, the 'stop' operation triggered
>>>> by virtio_bus_set_host_notifier() will not result in a call to
>>>> virtio_pci_ioeventfd_assign(assign=false). This leaves the memory
>>>> regions with stale notifiers and results on the next start triggering
>>>> the following assertion:
>>>>  kvm_mem_ioeventfd_add: error adding ioeventfd: File exists
>>>>  Aborted
>>>> This patch updates ioeventfd_started whenever the notifiers are set or
>>>> cleared, fixing this issue.
>>>> Signed-off-by: Felipe Franciosi <address@hidden>
>>> This also fixes vhost-net after reboot on s390/kvm for me
>> It does not fix it (the original breakage from e616c2f "virtio: remove
>> ioeventfd_disabled altogether") for me:
> Can you try Paolo's latest patches for this issue?
> http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg02834.html
> Specifically this:
> http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg02837.html

This one does work, thanks!


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