linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Wei Wang <wei.w.wang@intel.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
	virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org,
	akpm@linux-foundation.org, dgilbert@redhat.com
Cc: torvalds@linux-foundation.org, pbonzini@redhat.com,
	liliang.opensource@gmail.com, yang.zhang.wz@gmail.com,
	quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com,
	peterx@redhat.com, quintela@redhat.com,
	Halil Pasic <pasic@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting
Date: Fri, 28 Dec 2018 14:41:41 +0800	[thread overview]
Message-ID: <5C25C5A5.4080706@intel.com> (raw)
In-Reply-To: <e79b5c3d-aa89-6b99-00b1-c92c85fe214c@de.ibm.com>

On 12/27/2018 08:17 PM, Christian Borntraeger wrote:
>
> On 27.12.2018 12:59, Christian Borntraeger wrote:
>> On 27.12.2018 12:31, Christian Borntraeger wrote:
>>> This patch triggers random crashes in the guest kernel on s390 early during boot.
>>> No migration and no setting of the balloon is involved.
>>>
>> Adding Conny and Halil,
>>
>> As the QEMU provides no PAGE_HINT feature yet, this quick hack makes the
>> guest boot fine again:
>>
>>
>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
>> index 728ecd1eea305..aa2e1864c5736 100644
>> --- a/drivers/virtio/virtio_balloon.c
>> +++ b/drivers/virtio/virtio_balloon.c
>> @@ -492,7 +492,7 @@ static int init_vqs(struct virtio_balloon *vb)
>>                  callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
>>          }
>>   
>> -       err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
>> +       err = vb->vdev->config->find_vqs(vb->vdev, 3, //VIRTIO_BALLOON_VQ_MAX,
>>                                           vqs, callbacks, names, NULL, NULL);
>>          if (err)
>>                  return err;
>>
>>
>> To me it looks like that virtio_ccw_find_vqs will abort if any of the virtqueues
>> that it is been asked for does not exist (including the earlier ones).
>>
> This "hack" makes the random crashes go away, but the balloon interface itself
> does not work. (setting the value to anything will hang the guest).
> As patch 1 also modifies the main path, there seem to be additional issues, maybe
> endianess
>
> Looking at things like
>
> +		vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP;
> +		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
> +						  VIRTIO_BALLOON_CMD_ID_STOP);
> +		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
> +						  VIRTIO_BALLOON_CMD_ID_STOP);
>
>
> Why is cmd_id_received not using cpu_to_virtio32?
>

That conversion is only needed when we need to send the value to the device.
cmd_id_received doesn't need to be sent to the device.

Best,
Wei



      reply	other threads:[~2018-12-28  6:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27  1:32 Wei Wang
2018-08-27  1:32 ` [PATCH v37 1/3] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT Wei Wang
2018-12-27 12:03   ` Christian Borntraeger
2018-12-28  3:12     ` Wei Wang
2018-12-28  8:03       ` Christian Borntraeger
2018-08-27  1:32 ` [PATCH v37 2/3] mm/page_poison: expose page_poisoning_enabled to kernel modules Wei Wang
2018-08-27  1:32 ` [PATCH v37 3/3] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON Wei Wang
2018-10-25  0:58 ` [PATCH v37 0/3] Virtio-balloon: support free page reporting Michael S. Tsirkin
2018-10-25 10:18   ` Wei Wang
2018-12-27 11:31 ` Christian Borntraeger
2018-12-27 11:59   ` Christian Borntraeger
2018-12-27 12:17     ` Christian Borntraeger
2018-12-28  6:41       ` Wei Wang [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5C25C5A5.4080706@intel.com \
    --to=wei.w.wang@intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=borntraeger@de.ibm.com \
    --cc=cohuck@redhat.com \
    --cc=dgilbert@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=liliang.opensource@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mst@redhat.com \
    --cc=nilal@redhat.com \
    --cc=pasic@linux.ibm.com \
    --cc=pbonzini@redhat.com \
    --cc=peterx@redhat.com \
    --cc=quan.xu0@gmail.com \
    --cc=quintela@redhat.com \
    --cc=riel@redhat.com \
    --cc=torvalds@linux-foundation.org \
    --cc=virtio-dev@lists.oasis-open.org \
    --cc=virtualization@lists.linux-foundation.org \
    --cc=yang.zhang.wz@gmail.com \
    --subject='Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).