Re: Xenbus issues on Qubes OS / win10

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 27/06/2023 11:37, Paul Durrant wrote:
> On 23/06/2023 19:50, Rafał Wojdyła wrote:
> > On 23 cze 2023 17:37, Rafał Wojdyła wrote:
> > > Hello,
> > >
> > > I'm trying the latest PV drivers on Qubes OS (backend is Xen 4.14.5) 
> > > with Windows 10 pro and having some issues. Mainly, xenbus fails to 
> > > initialize properly. I've attached a debug output, the main issue 
> > > seems to be this:
> > > xenbus|StoreAcquire: ====>
> > > xenbus|GnttabAcquire: ====>
> > > xenbus|RangeSetPop: fail3
> > > xenbus|RangeSetPop: fail2
> > > xenbus|RangeSetPop: fail1 (c000009a)
> > > xenbus|FdoAllocateHole: fail1 (c000009a)
> > > xenbus|GnttabAcquire: fail2
> > > xenbus|GnttabAcquire: fail1 (c000009a)
> > > xenbus|StoreAcquire: fail1 (c000009a)
> > > xenbus|FdoD3ToD0: fail6
> > >
> > > ...which seems pretty suspicious. It's been some years since I looked 
> > > at the drivers' code so any ideas as to what may be causing this are 
> > > welcome :)
> > Followup: in xenbus/gnttab/GnttabAcquire()
> >
> > status = GrantTableQuerySize(NULL, &Context->MaximumFrameCount);
> >
> > Context->MaximumFrameCount is 2048 for me, which is bigger than 1 << 
> > PAGE_ORDER_2M, which seems to be the limit for FDO memory hole size.
> Hmm. Ok - we should probably put something in there to either expand the 
> hole, use another one or - probably simpler - query the grant table size 
> up-front to correctly size the hole.
Wasn't that simple... Trying to allocate a single memory hole to 
accommodate a 2048 entry grant table just didn't fly on my test VM. So 
I've re-worked things to both get rid of the single memory hole, and to 
have the grant table deal with non-contiguous GFNs.
  Paul