* [Qemu-devel] [virtio-net] migration
@ 2016-05-27 12:59 Catalin Vasile
2016-06-09 12:59 ` Stefan Hajnoczi
0 siblings, 1 reply; 2+ messages in thread
From: Catalin Vasile @ 2016-05-27 12:59 UTC (permalink / raw)
To: qemu-devel@nongnu.org
Hi,
What is the workflow for virtio-net devices when migrating the VM it belongs to?
>From what I understand so far the stop() primitives in qemu are called for virtio_net and vhost_net which makes the virtqueue reset such that it seems the queues are completely empty.
How does the guest know that the jobs he sent on the virtqueue were discarded so that he can retry or release resources that were used for managing those jobs/packets?
Catalin Vasile
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [virtio-net] migration
2016-05-27 12:59 [Qemu-devel] [virtio-net] migration Catalin Vasile
@ 2016-06-09 12:59 ` Stefan Hajnoczi
0 siblings, 0 replies; 2+ messages in thread
From: Stefan Hajnoczi @ 2016-06-09 12:59 UTC (permalink / raw)
To: Catalin Vasile; +Cc: qemu-devel@nongnu.org
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On Fri, May 27, 2016 at 12:59:51PM +0000, Catalin Vasile wrote:
> What is the workflow for virtio-net devices when migrating the VM it belongs to?
> From what I understand so far the stop() primitives in qemu are called for virtio_net and vhost_net which makes the virtqueue reset such that it seems the queues are completely empty.
> How does the guest know that the jobs he sent on the virtqueue were discarded so that he can retry or release resources that were used for managing those jobs/packets?
No, virtqueues stay as-is across migration. vring state (e.g.
last_avail_idx) is migrated so that the new QEMU can pick up where the
old one left off.
See hw/virtio/virtio.c load/save code to learn more.
Stefan
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2016-05-27 12:59 [Qemu-devel] [virtio-net] migration Catalin Vasile
2016-06-09 12:59 ` Stefan Hajnoczi
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