From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51452) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBHAq-0007LY-Oe for qemu-devel@nongnu.org; Thu, 18 May 2017 04:52:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dBHAl-0006n0-U9 for qemu-devel@nongnu.org; Thu, 18 May 2017 04:52:44 -0400 Date: Thu, 18 May 2017 16:52:33 +0800 From: Fam Zheng Message-ID: <20170518085233.GG5764@lemon.lan> References: <149500797926.28874.3877030098009500731.stgit@bahia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <149500797926.28874.3877030098009500731.stgit@bahia> Subject: Re: [Qemu-devel] [Qemu-stable] [RESEND PATCH] virtio: allow broken device to notify guest List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, Cornelia Huck , qemu-stable@nongnu.org, "Michael S. Tsirkin" On Wed, 05/17 10:17, Greg Kurz wrote: > According to section 2.1.2 of the virtio-1 specification: > > "The device SHOULD set DEVICE_NEEDS_RESET when it enters an error state that > a reset is needed. If DRIVER_OK is set, after it sets DEVICE_NEEDS_RESET, > the device MUST send a device configuration change notification to the > driver." > > Commit "f5ed36635d8f virtio: stop virtqueue processing if device is broken" > introduced a virtio_error() call that just does that: > > - internally mark the device as broken > - set the DEVICE_NEEDS_RESET bit in the status > - send a configuration change notification > > Unfortunately, virtio_notify_vector(), called by virtio_notify_config(), > returns right away when the device is marked as broken and the notification > isn't sent in this case. > > The spec doesn't say whether a broken device can send notifications > in other situations or not. But since the driver isn't supposed to do > anything but to reset the device, it makes sense to keep the check in > virtio_notify_config(). > > Marking the device as broken AFTER the configuration change notification was > sent is enough to fix the issue. > > Signed-off-by: Greg Kurz > Reviewed-by: Cornelia Huck > --- > hw/virtio/virtio.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > Re-sending this patch with Cornelia's Reviewed-by and Cc'ing qemu-stable > since this is a spec violation, as suggested in: > > Message-ID: <20170427183237-mutt-send-email-mst@kernel.org> > > Cheers, > > -- > Greg > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 03592c542a55..890b4d7eb751 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -2451,12 +2451,12 @@ void GCC_FMT_ATTR(2, 3) virtio_error(VirtIODevice *vdev, const char *fmt, ...) > error_vreport(fmt, ap); > va_end(ap); > > - vdev->broken = true; > - > if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { > virtio_set_status(vdev, vdev->status | VIRTIO_CONFIG_S_NEEDS_RESET); > virtio_notify_config(vdev); > } > + > + vdev->broken = true; > } > > static void virtio_memory_listener_commit(MemoryListener *listener) > > Reviewed-by: Fam Zheng