On Fri, Jan 29, 2021 at 05:34:36PM -0600, Jonathon Jongsma wrote:
> On Thu, 7 Jan 2021 17:43:54 +0100
> Erik Skultety <eskul...@redhat.com> wrote:
> 
> > > Tested with v6.10.0-283-g1948d4e61e.
> > > 
> > > 1.Can define/start/destroy mdev device successfully;
> > > 
> > > 2.'virsh nodedev-list' has no '--active' option, which is
> > > inconsistent with the description in the patch:
> > > # virsh nodedev-list --active
> > > error: command 'nodedev-list' doesn't support option --active
> > > 
> > > 3.virsh client hang when trying to destroy a mdev device which is
> > > using by a vm, and after that all 'virsh nodev*' cmds will hang. If
> > > restarting llibvirtd after that, libvirtd will hang.  
> > 
> > It hangs because underneath a write to the 'remove' sysfs attribute
> > is now blocking for some reason and since we're relying on mdevctl to
> > do it for us, hence "it hangs". I'm not trying to make an excuse,
> > it's plain wrong. I'd love to rely on such a basic functionality, but
> > it looks like we'll have to go with a extremely ugly workaround and
> > try to get the list of active domains from the nodedev driver and see
> > whether any of them has the device assigned before we try to destroy
> > the mdev via the nodedev driver.
> 
> So, I've been trying to figure out a way to do this, but as far as
> I know, there's no way to get a list of active domains from within the
> nodedev driver, and I can't think of any better ways to handle it. Any
> ideas?

Correct, the nodedev driver isn't permitted to talk to any of the virt
drivers.

Is there anything in sysfs which reports whether the device is in use ?

Regards,
Daniel
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