Re: [Xen-devel] Xen 4.10.x and PCI passthrough

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Sep 19, 2018 at 04:48:58PM +0200, Roger Pau Monné wrote:
> On Mon, Sep 17, 2018 at 12:05:26PM +0200, Andreas Kinzler wrote:
> > Hello Roger,
> > 
> > > > Some weeks ago I tried a quite new version of Xen 4.10.2-pre 
> > > > (http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=a645331a9f4190e92ccf41a950bc4692f8904239)
> > > > and the PCI card (LSI SAS HBA) using Windows 2012 R2 as a guest.
> > > > Everything
> > > > works but only to the point where Windows reboots -> then the card is no
> > > > longer usable. If you destroy the domain and recreate the card again
> > > > Did I miss something simple or should we analyze the problem again
> > > > using
> > > > similar debug prints as before?
> > > Not sure, but it doesn't look to me like this issue is related to the
> > > one fixed by the patches mentioned above, I think this is a different
> > > issue, and by the looks of it it's a toolstack issue.
> > > Can you paste the output of `xl -vvv create <config.cfg>` and the
> > > contents of the log that you will find in
> > > /var/log/xen/xl-<domain-name>.log after you have attempted a reboot?
> > 
> > xl-domain.log is attached. From what I can see, the problem is that the card
> > is deleted after domid 3 and not added back later. To confirm I ran "xl
> > pci-list winsrv" during domid 3 and the card is shown. After Windows reboot
> > (domid 4) "xl pci-list winsrv" gives an empty output.
> 
> Hello,
> 
> I'm not very familiar with the way xl/libxl keeps state between
> reboots, I think Wei (now on Cc) was the last one to look into this.
> If not I can try to take a look later this week.

Rebooting the domain involves saving the domain state and recreating the
guest from that state.

PCI devices don't get saved when saving domain state. The framework is
generic, but there are some missing hooks for PCI type devices.

See libxl_domain.c:libxl_retrieve_domain_configuration and libxl_pci.c.

Wei.

> 
> Roger.

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