From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56351) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fY8c2-00061F-GS for qemu-devel@nongnu.org; Wed, 27 Jun 2018 07:27:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fY8by-0008R2-G9 for qemu-devel@nongnu.org; Wed, 27 Jun 2018 07:27:50 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:41670 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fY8by-0008Pv-AP for qemu-devel@nongnu.org; Wed, 27 Jun 2018 07:27:46 -0400 Date: Wed, 27 Jun 2018 12:27:41 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180627112741.GH30628@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180627112520.26085-1-pagupta@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180627112520.26085-1-pagupta@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] virtio-rng: process pending requests when driver is ready List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pankaj Gupta Cc: mst@redhat.com, amit@kernel.org, qemu-devel@nongnu.org, slopezpa@redhat.com, stefanha@redhat.com On Wed, Jun 27, 2018 at 04:55:20PM +0530, Pankaj Gupta wrote: > virtio-rng device causing old guest kernels(2.6.32) to hang on latest qemu. > The driver attempts to read from the virtio-rng device too early in it's > initialization. Qemu detects guest is not ready and returns, resulting in > hang. Presumably this all worked previously at some point, so do you know what change in QEMU has caused a regression in this regard. > > Fix is to handle pending request when guest is running and driver status is > set to 'VIRTIO_CONFIG_S_DRIVER_OK'. > > Reported-by: Sergio lopez > Signed-off-by: Stefan Hajnoczi > Signed-off-by: Pankaj Gupta > --- > v1->v2: Update new status value early only for virtio-rng (Stefan) > > hw/virtio/virtio-rng.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c > index 289bbcac03..855f1b41d1 100644 > --- a/hw/virtio/virtio-rng.c > +++ b/hw/virtio/virtio-rng.c > @@ -156,6 +156,19 @@ static void check_rate_limit(void *opaque) > vrng->activate_timer = true; > } > > +static void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status) > +{ > + VirtIORNG *vrng = VIRTIO_RNG(vdev); > + > + if (!vdev->vm_running) { > + return; > + } > + vdev->status = status; > + > + /* Something changed, try to process buffers */ > + virtio_rng_process(vrng); > +} > + > static void virtio_rng_device_realize(DeviceState *dev, Error **errp) > { > VirtIODevice *vdev = VIRTIO_DEVICE(dev); > @@ -261,6 +274,7 @@ static void virtio_rng_class_init(ObjectClass *klass, void *data) > vdc->realize = virtio_rng_device_realize; > vdc->unrealize = virtio_rng_device_unrealize; > vdc->get_features = get_features; > + vdc->set_status = virtio_rng_set_status; > } > > static const TypeInfo virtio_rng_info = { > -- > 2.14.3 > > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|