From: Stefan Hajnoczi <stefanha@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: fam@euphon.net, kwolf@redhat.com, den@virtuozzo.com,
qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
ehabkost@redhat.com
Subject: Re: [PATCH v1 1/4] virtio: protect non-modern devices from too big virtqueue size setting
Date: Wed, 6 Nov 2019 10:18:12 +0100 [thread overview]
Message-ID: <20191106091812.GF189998@stefanha-x1.localdomain> (raw)
In-Reply-To: <20191105155357-mutt-send-email-mst@kernel.org>
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On Tue, Nov 05, 2019 at 03:56:43PM -0500, Michael S. Tsirkin wrote:
> On Tue, Nov 05, 2019 at 07:11:02PM +0300, Denis Plotnikov wrote:
> > @@ -47,6 +48,15 @@ static void virtio_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
> > VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
> > DeviceState *proxy = DEVICE(vpci_dev);
> > char *bus_name;
> > + bool modern = virtio_pci_modern(vpci_dev);
> > + uint32_t virtqueue_size = vs->conf.virtqueue_size;
> > +
> > + if (!modern && virtqueue_size > 128) {
> > + error_setg(errp,
> > + "too big virtqueue size (%u, max: 128) "
> > + "for non-modern virtio device", virtqueue_size);
> > + return;
> > + }
>
> why? what is illegal about 256 for legacy?
I think it was mentioned that this limit is specific to SeaBIOS
src/hw/virtio-pci.c:vp_find_vq():
#define MAX_QUEUE_NUM (128)
...
if (num > MAX_QUEUE_NUM) {
dprintf(1, "ERROR: queue size %d > %d\n", num, MAX_QUEUE_NUM);
goto fail;
}
I'm not sure there is anything we can do in QEMU. Either you can let
SeaBIOS fail, or if you want something more user-friendly, then the
management tool can implement a check based on the SeaBIOS version and
the -device virtio-blk-pci,queue-size=SIZE property value.
Stefan
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next prev parent reply other threads:[~2019-11-06 9:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 16:11 [PATCH v1 0/4] virtio: fix IO request length in virtio SCSI/block Denis Plotnikov
2019-11-05 16:11 ` [PATCH v1 1/4] virtio: protect non-modern devices from too big virtqueue size setting Denis Plotnikov
2019-11-05 20:56 ` Michael S. Tsirkin
2019-11-06 7:46 ` Denis Plotnikov
2019-11-06 9:01 ` Stefan Hajnoczi
2019-11-06 9:19 ` Stefan Hajnoczi
2019-11-06 11:33 ` Michael S. Tsirkin
2019-11-06 9:18 ` Stefan Hajnoczi [this message]
2019-11-06 11:51 ` Michael S. Tsirkin
2019-11-05 16:11 ` [PATCH v1 2/4] virtio: make seg_max virtqueue size dependent Denis Plotnikov
2019-11-05 20:51 ` Michael S. Tsirkin
2019-11-06 10:07 ` Denis Lunev
2019-11-06 11:54 ` Michael S. Tsirkin
2019-11-08 7:43 ` Denis Plotnikov
2019-11-08 9:52 ` Michael S. Tsirkin
2019-11-05 16:11 ` [PATCH v1 3/4] virtio: increase virtuqueue sizes in new machine types Denis Plotnikov
2019-11-05 20:52 ` Michael S. Tsirkin
2019-11-05 16:11 ` [PATCH v1 4/4] iotests: add test for virtio-scsi and virtio-blk machine type settings Denis Plotnikov
2019-11-06 9:24 ` Stefan Hajnoczi
2019-11-06 10:04 ` Max Reitz
2019-11-06 19:26 ` Eduardo Habkost
2019-11-07 16:30 ` Cleber Rosa
2019-11-08 7:08 ` Denis Plotnikov
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