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From: Mark McLoughlin <markmc@redhat.com>
To: Phil Ten <phil.info@dafweb.com>
Cc: kvm@vger.kernel.org
Subject: Re: kvm process exit on virtio error
Date: Wed, 11 Feb 2009 19:59:46 +0000	[thread overview]
Message-ID: <1234382386.14052.244.camel@blaa> (raw)
In-Reply-To: <23212937.21234352516353.JavaMail.root@ns354536.ovh.net>

Hi,

On Wed, 2009-02-11 at 12:41 +0100, Phil Ten wrote:
> Hello, 
> 
> My kvm processes are exiting on what I think are VIRTIO errors:
> 
> Guest moved used index from 24543 to 24606

This is very strange. The code in question is:

static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
{
    uint16_t num_heads = vring_avail_idx(vq) - idx;

	/* Check it isn't doing very strange things with descriptor numbers. */
    if (num_heads > vq->vring.num) {
        fprintf(stderr, "Guest moved used index from %u to %u",
	            idx, vring_avail_idx(vq));
        exit(1);
...

i.e. for virtio_net, vq->vring.num == 256 and 24606 - 24543 == 63, so it
doesn't make much sense.

Does this happen under heavy network traffic? Have you tried virtio_blk?

Thanks,
Mark.


  reply	other threads:[~2009-02-11 19:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-02-11 11:41 kvm process exit on virtio error Phil Ten
2009-02-11 19:59 ` Mark McLoughlin [this message]
2009-02-12 10:11   ` Phil Ten

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