Re: [Xen-devel] [PATCH 7/7] ioreq: provide support for long-running operations...

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Aug 22, 2019 at 11:15:50AM +0200, Paul Durrant wrote:
> > -----Original Message-----
> > From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> > Sent: 21 August 2019 15:59
> > To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > Cc: Roger Pau Monne <roger.pau@xxxxxxxxxx>; Paul Durrant 
> > <Paul.Durrant@xxxxxxxxxx>; Jan Beulich
> > <jbeulich@xxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu 
> > <wl@xxxxxxx>; George Dunlap
> > <George.Dunlap@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Julien 
> > Grall <julien.grall@xxxxxxx>;
> > Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Stefano Stabellini 
> > <sstabellini@xxxxxxxxxx>; Tim
> > (Xen.org) <tim@xxxxxxx>
> > Subject: [PATCH 7/7] ioreq: provide support for long-running operations...
> > 
> > ...and switch vPCI to use this infrastructure for long running
> > physmap modification operations.
> > 
> > This allows to get rid of the vPCI specific modifications done to
> > handle_hvm_io_completion and allows generalizing the support for
> > long-running operations to other internal ioreq servers. Such support
> > is implemented as a specific handler that can be registers by internal
> > ioreq servers and that will be called to check for pending work.
> > Returning true from this handler will prevent the vcpu from running
> > until the handler returns false.
> 
> Rather than having another callback can the handler not be re-called with 
> same ioreq? It could return different values depending on whether there is 
> more work to do (requiring another call) or whether it is done and the vcpu 
> can be resumed. Would that work?

I guess this would work also. The issue with this approach is that I
would have to find somewhere to store the ioreq while the operation is
being processed, which is not required with the proposed two handler
approach.

Thanks, Roger.

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