Re: [Xen-users] substantial shutdown delay for PV guests with PCI -passthrough

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Mar 19, 2014 at 11:26:24AM +0000, Ian Campbell wrote:
> On Wed, 2014-03-19 at 01:25 +0100, Atom2 wrote:
> > So it seems that pretty much at the start of the 10s delay the state 
> > changed from 4 to 6 and stays at that value even after the first 10s 
> > delay is over - whatever that means.
> 
> 4 == Connected
> 6 == Closed
> 
> I think what is happening is that the domain is shutting down, which
> causes pciback to transition to the closed state (because the f.e. went
> away, so this is a reasonable thing for it to do).
> 
> The bug appears to be that libxl is trying to "hot unplug" the devices
> on shutdown when they have already been effectively "cold unplugged" by
> the domain going down.
> 
> Perhaps libxl__device_pci_remove_xenstore should observe that the state
> is > 4 (hence closing/closed) and not bother doing anything, i.e. only
> waiting iff the state is <4 (init, connecting etc)? Or unconditionally
> removing the nodes if state > 4. (perhaps state 7, reconfiguring needs
> handling here too)
> 
> Or perhaps the force parameter passed to remove_common (which indicates
> destroy rather than unplug) ought to be propagated down to this code and
> $something done with it.
> 
> Roger, Ian, any thoughts on that?

This reminds me of this bug:

commit 098b1aeaf4d6149953b8f1f8d55c21d85536fbff
Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date:   Mon Jun 10 16:48:09 2013 -0400

    xen/pcifront: Deal with toolstack missing 'XenbusStateClosing' state.

... snip..
    
    In other words, this 4(Connected)->5(Closing)->4(Connected) state
    was expected, while 4(Connected)->.... anything but 5(Closing)->4(Connected)
    was not. This patch removes that aggressive check and allows
    Xen pcifront to work with the 'xl' toolstack (for one or more
    PCI devices) and with 'xm' toolstack (for more than two PCI
    devices).
    
But this seems to be a different state issue?

Ariel/Atom2, do you see this behavior with 'xend'? And what is the version of Linux
kernel you are running as guest?
> 
> Ian.
>