RE: [PATCH v9 0/8] domain context infrastructure

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>
> Sent: 29 September 2020 13:06
> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx>
> Cc: Lengyel, Tamas <tamas.lengyel@xxxxxxxxx>; paul@xxxxxxx; 
> xen-devel@xxxxxxxxxxxxxxxxxxxx; Andrew
> Cooper <andrew.cooper3@xxxxxxxxxx>; Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>; 
> George Dunlap
> <george.dunlap@xxxxxxxxxx>; Ian Jackson <ian.jackson@xxxxxxxxxxxxx>; Jan 
> Beulich <jbeulich@xxxxxxxx>;
> Julien Grall <julien@xxxxxxx>; Marek Marczykowski-Górecki 
> <marmarek@xxxxxxxxxxxxxxxxxxxxxx>; Roger Pau
> Monné <roger.pau@xxxxxxxxxx>; Stefano Stabellini <sstabellini@xxxxxxxxxx>; 
> Volodymyr Babchuk
> <Volodymyr_Babchuk@xxxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: RE: [EXTERNAL] [PATCH v9 0/8] domain context infrastructure
> 
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> On Tue, Sep 29, 2020 at 7:54 AM Durrant, Paul <pdurrant@xxxxxxxxxxxx> wrote:
> >
> > > -----Original Message-----
> > > From: Lengyel, Tamas <tamas.lengyel@xxxxxxxxx>
> > > Sent: 28 September 2020 15:17
> > > To: paul@xxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx
> > > Cc: Durrant, Paul <pdurrant@xxxxxxxxxxxx>; 'Andrew Cooper' 
> > > <andrew.cooper3@xxxxxxxxxx>; 'Daniel De
> > > Graaf' <dgdegra@xxxxxxxxxxxxx>; 'George Dunlap' 
> > > <george.dunlap@xxxxxxxxxx>; 'Ian Jackson'
> > > <ian.jackson@xxxxxxxxxxxxx>; 'Jan Beulich' <jbeulich@xxxxxxxx>; 'Julien 
> > > Grall' <julien@xxxxxxx>;
> > > 'Marek Marczykowski-Górecki' <marmarek@xxxxxxxxxxxxxxxxxxxxxx>; 'Roger 
> > > Pau Monné'
> > > <roger.pau@xxxxxxxxxx>; 'Stefano Stabellini' <sstabellini@xxxxxxxxxx>; 
> > > 'Volodymyr Babchuk'
> > > <Volodymyr_Babchuk@xxxxxxxx>; 'Wei Liu' <wl@xxxxxxx>
> > > Subject: RE: [EXTERNAL] [PATCH v9 0/8] domain context infrastructure
> > >
> > > CAUTION: This email originated from outside of the organization. Do not 
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> > >
> > >
> > > > > Hi Paul,
> > > > > Could you push a git branch somewhere for this series? I would like to
> > > > > see this being integrated with VM forking and if its not too much
> > > > > effort just create the patch for that so that it could be appended to 
> > > > > the
> > > > series.
> > > > >
> > > >
> > > > Hi Tamas,
> > > >
> > > >   Done. See
> > > > https://xenbits.xen.org/gitweb/?p=people/pauldu/xen.git;a=shortlog;h=refs/h
> > > > eads/domain-save14
> > > >
> > > >   Cheers,
> > > >
> > > >     Paul
> > >
> > > Hi Paul,
> > > I added a small patch that would save & load the PV context from one 
> > > domain to another that would
> be
> > > called during VM forking. Please take a look at
> > >
> https://xenbits.xen.org/gitweb/?p=people/tklengyel/xen.git;a=commitdiff;h=1843ca7302e415317fdb9a63b3a4
> > > d29a385dc766;hp=8149296fdf80c73727e61cea6fe3251aecf8b333. I called the 
> > > function
> copy_pv_domaincontext
> > > for now as that seemed like the most appropriate description for it. 
> > > Please let me know if this
> looks
> > > good to you. I'm still testing it but if everything checks out it would 
> > > be nice to just append
> this
> > > patch to your series.
> >
> > Hi Tamas,
> >
> >   The code structure appears to be ok... just some cosmetic tweaks:
> >
> > - I think you should call the function simply 'copy_domaincontext' as the 
> > idea is that all state
> (including what is now in hvm context) will be consolidated
> 
> Sure, I wasn't entirely clear about whether this will be limited to PV
> context or if it will eventually add the hvm stuff too. Right now I
> still would have to do that separately.
> 
> > - The prevailing style in domctl.c AFAICS is that assignments are mostly 
> > not done inside if
> statements. Personally I think this is a good thing.
> 
> I think it cuts down on function sizes when all that is being done
> after an assigment is a NULL-check. No need for a separate line for it
> but I also don't care that much. So if it's more important to whoever
> maintains this to keep the style consistent in this regard I can
> change it.
> 
> >
> >   Once you have something ready to go then I'd be happy to tag it onto my 
> > series if I need to do a
> v10... but I'm currently hoping that won't be necessary.
> 
> I think I'll wait until HVM context is included in the framework as
> well so that we can just switch over everything at once.
> 

It may be a while before I have everything moved over so you may still want to 
go ahead with this patch if the delay is likely to block things. Also, without 
this I assume any records I port over from HVM context (and hence remove the 
save code) are going to cause breakage for VM forking?

  Paul

> Tamas