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Re: [Qemu-devel] [PATCH v2] vhost: Update 'ioeventfd_started' with host
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH v2] vhost: Update 'ioeventfd_started' with host notifiers |
Date: |
Thu, 10 Nov 2016 15:45:14 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
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
Tested-by: Christian Borntraeger <address@hidden>
>
> [1] http://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg07748.html
> [2] http://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg07760.html
> ---
> v1->v2:
> - Update ioeventfd_started in vhost_dev_enable/disable_notifiers()
> instead of vhost_scsi_start/stop().
> - Reword the commit message accordingly.
> ---
> hw/virtio/vhost.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 131f164..1290963 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1205,6 +1205,7 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev,
> VirtIODevice *vdev)
> goto fail_vq;
> }
> }
> + VIRTIO_BUS(qbus)->ioeventfd_started = true;
>
> return 0;
> fail_vq:
> @@ -1239,6 +1240,7 @@ void vhost_dev_disable_notifiers(struct vhost_dev
> *hdev, VirtIODevice *vdev)
> }
> assert (r >= 0);
> }
> + VIRTIO_BUS(qbus)->ioeventfd_started = false;
> virtio_device_start_ioeventfd(vdev);
> }
>