Re: [Qemu-devel] [PATCH 0/7] virtio: avoid inappropriate QEMU termination

[Gonglei (Arei)]

Hi Greg,



> -----Original Message-----
> From: Greg Kurz [mailto:address@hidden
> Sent: Thursday, September 22, 2016 3:22 PM
> To: Gonglei (Arei)
> Cc: address@hidden; Kevin Wolf; Michael S. Tsirkin; Jason Wang; Max
> Reitz; Aneesh Kumar K.V; Stefan Hajnoczi; Cornelia Huck; Paolo Bonzini
> Subject: Re: [Qemu-devel] [PATCH 0/7] virtio: avoid inappropriate QEMU
> termination
> 
> On Thu, 22 Sep 2016 06:55:43 +0000
> "Gonglei (Arei)" <address@hidden> wrote:
> 
> > > -----Original Message-----
> > > From: Greg Kurz [mailto:address@hidden
> > > Sent: Thursday, September 22, 2016 2:43 PM
> > > To: Gonglei (Arei)
> > > Cc: address@hidden; Kevin Wolf; Michael S. Tsirkin; Jason Wang;
> Max
> > > Reitz; Aneesh Kumar K.V; Stefan Hajnoczi; Cornelia Huck; Paolo Bonzini
> > > Subject: Re: [Qemu-devel] [PATCH 0/7] virtio: avoid inappropriate QEMU
> > > termination
> > >
> > > On Thu, 22 Sep 2016 09:19:49 +0800
> > > Gonglei <address@hidden> wrote:
> > >
> > > > On 2016/9/21 21:13, Greg Kurz wrote:
> > > > > This series is a follow up to Stefan's work to eradicate most calls to
> > > > > exit() we currently have in the virtio code.
> > > > >
> > > > > It addresses all exit() call sites in the blk, net and scsi device 
> > > > > code,
> > > > > where the error is about a missing or malformed in/out header sent by
> > > > > the guest. They are converted to use virtio_error() and stop any
> processing,
> > > > > instead of exiting.
> > > > >
> > > > Actually if you just stop procesing when encounter a missing in/out 
> > > > header
> > > but
> > > > send a interrupt to the guest, the guest maybe be stuck.
> > > virtio_net_handle_ctrl()
> > >
> > > The virtio_error() function sets the device status to DEVICE_NEEDS_RESET
> and
> > > does send a device configuration change interrupt to the guest, so it can
> take
> > > appropriate action (i.e. reset the device).
> > >

I saw virtio_error() only handle the virtio 1.0 device, the legacy virtio 
device may
still stuck, am I right?

+void GCC_FMT_ATTR(2, 3) virtio_error(VirtIODevice *vdev, const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, 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);
+    }
+}


Regards,
-Gonglei

> > That's appropriate. Where is realization of virtio_error() ?
> > I'm sure I missed something.
> >
> 
> Sorry for that... Michael already "lectured" me about not providing these
> details. He is right indeed :)
> 
> 
> This is work in progress by Stefan. The latest version of the patchset (v5) 
> was
> posted yesterday:
> 
> <address@hidden>
> 
> The virtio_error() function itself is in patch 2/9:
> 
> <address@hidden>
> 
> Cheers.
> 
> --
> Greg
> 
> > Regards,
> > -Gonglei
> >
> > > Maybe I should have mentioned that in the changelog...
> > >
> > > Cheers.
> > >
> > > --
> > > Greg
> > >
> > > > is an example, the guest frontend driver infinite loop to wait the
> interrupt's
> > > coming.
> > > > The guest can't work anymore though you don't exit the Qemu process .
> > > >
> > > > Regards,
> > > > -Gonglei
> > > >
> > > > > The remaining call sites are related to a host misconfiguration or a
> > > > > migration stream issue.
> > > > >
> > > > > The 9P code currently calls assert() instead of exit(), but it also 
> > > > > about
> > > > > malformed or missing headers, so it gets converted the same way.
> > > > >
> > > > > Next work will be to check all assert() call sites in the device 
> > > > > code, in
> > > > > case some of them actually refer to a bug in the guest, and should be
> > > > > converted to use virtio_error() as well.
> > > > >
> > > > > ---
> > > > >
> > > > > Greg Kurz (7):
> > > > >       virtio-9p: handle handle_9p_output() error
> > > > >       virtio-blk: handle virtio_blk_handle_request() errors
> > > > >       virtio-net: handle virtio_net_handle_ctrl() error
> > > > >       virtio-net: handle virtio_net_receive() errors
> > > > >       virtio-net: handle virtio_net_flush_tx() errors
> > > > >       virtio-scsi: convert virtio_scsi_bad_req() to use virtio_error()
> > > > >       virtio-scsi: handle virtio_scsi_set_config() error
> > > > >
> > > > >
> > > > >  hw/9pfs/virtio-9p-device.c |   14 ++++++++++--
> > > > >  hw/block/virtio-blk.c      |   27 +++++++++++++++--------
> > > > >  hw/net/virtio-net.c        |   51
> > > +++++++++++++++++++++++++-------------------
> > > > >  hw/scsi/virtio-scsi.c      |   21 ++++++++++--------
> > > > >  4 files changed, 70 insertions(+), 43 deletions(-)
> > > > >
> > > > > --
> > > > > Greg
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> >