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From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Richard W.M. Jones" <rjones@redhat.com>
Cc: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, pbonzini@redhat.com,
	hch@lst.de
Subject: Re: [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN.
Date: Fri, 11 Aug 2017 00:41:47 +0300	[thread overview]
Message-ID: <20170811003621-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20170810213511.GB10017@redhat.com>

On Thu, Aug 10, 2017 at 10:35:11PM +0100, Richard W.M. Jones wrote:
> On Fri, Aug 11, 2017 at 12:31:44AM +0300, Michael S. Tsirkin wrote:
> > Then we probably should fail probe if vq size is too small.
> 
> What does this mean?
> 
> Rich.

We must prevent driver from submitting s/g lists > vq size to device.


Either tell linux to avoid s/g lists that are too long, or
simply fail request if this happens, or refuse to attach driver to device.

Later option would look something like this within probe:

        for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++)
		if (vqs[i]->num < MAX_SG_USED_BY_LINUX)
			goto err;


I don't know what's MAX_SG_USED_BY_LINUX though.

> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-builder quickly builds VMs from scratch
> http://libguestfs.org/virt-builder.1.html

WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Richard W.M. Jones" <rjones@redhat.com>
Cc: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
	jasowang@redhat.com, linux-scsi@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, hch@lst.de,
	pbonzini@redhat.com
Subject: Re: [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN.
Date: Fri, 11 Aug 2017 00:41:47 +0300	[thread overview]
Message-ID: <20170811003621-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20170810213511.GB10017@redhat.com>

On Thu, Aug 10, 2017 at 10:35:11PM +0100, Richard W.M. Jones wrote:
> On Fri, Aug 11, 2017 at 12:31:44AM +0300, Michael S. Tsirkin wrote:
> > Then we probably should fail probe if vq size is too small.
> 
> What does this mean?
> 
> Rich.

We must prevent driver from submitting s/g lists > vq size to device.


Either tell linux to avoid s/g lists that are too long, or
simply fail request if this happens, or refuse to attach driver to device.

Later option would look something like this within probe:

        for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++)
		if (vqs[i]->num < MAX_SG_USED_BY_LINUX)
			goto err;


I don't know what's MAX_SG_USED_BY_LINUX though.

> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-builder quickly builds VMs from scratch
> http://libguestfs.org/virt-builder.1.html

  reply	other threads:[~2017-08-10 21:41 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-10 16:40 [PATCH 0/2] virtio_scsi: Set can_queue based on size of virtqueue Richard W.M. Jones
2017-08-10 16:40 ` [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN Richard W.M. Jones
2017-08-10 16:47   ` Paolo Bonzini
2017-08-10 16:47     ` Paolo Bonzini
2017-08-10 21:21   ` Michael S. Tsirkin
2017-08-10 21:30     ` Richard W.M. Jones
2017-08-10 21:30     ` Richard W.M. Jones
2017-08-10 21:31       ` Michael S. Tsirkin
2017-08-10 21:31         ` Michael S. Tsirkin
2017-08-10 21:35         ` Richard W.M. Jones
2017-08-10 21:35           ` Richard W.M. Jones
2017-08-10 21:41           ` Michael S. Tsirkin [this message]
2017-08-10 21:41             ` Michael S. Tsirkin
2017-08-10 21:50             ` Richard W.M. Jones
2017-08-10 21:50             ` Richard W.M. Jones
2017-08-11 14:09             ` Paolo Bonzini
2017-08-11 17:23               ` Michael S. Tsirkin
2017-08-11 17:23                 ` Michael S. Tsirkin
2017-08-11 18:36                 ` Paolo Bonzini
2017-08-11 18:36                 ` Paolo Bonzini
2017-08-11 14:09             ` Paolo Bonzini
2017-08-10 21:21   ` Michael S. Tsirkin
2017-08-10 16:40 ` Richard W.M. Jones
2017-08-10 16:40 ` [PATCH 2/2] virtio: virtio_scsi: Set can_queue to the length of the virtqueue Richard W.M. Jones
2017-08-10 16:40 ` Richard W.M. Jones
2017-08-10 16:46   ` Paolo Bonzini
2017-08-10 16:46   ` Paolo Bonzini

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