Re: [Xen-devel] [PATCH 2/6] vTPM: add HVM_PARAM_STUBDOM_VTPM parameter for HVM virtual machine

["Xu, Quan" <quan.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> Sent: Saturday, November 01, 2014 1:51 AM
> To: Xu, Quan
> Cc: Stefano Stabellini; Andrew Cooper; xen-devel@xxxxxxxxxxxxx;
> ian.jackson@xxxxxxxxxxxxx; tim@xxxxxxx; keir@xxxxxxx; ian.campbell@xxxxxxxxxx;
> jbeulich@xxxxxxxx
> Subject: RE: [Xen-devel] [PATCH 2/6] vTPM: add
> HVM_PARAM_STUBDOM_VTPM parameter for HVM virtual machine
> 
> On Thu, 30 Oct 2014, Xu, Quan wrote:
> > > -----Original Message-----
> > > From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> > > Sent: Thursday, October 30, 2014 9:35 PM
> > > To: Andrew Cooper
> > > Cc: Xu, Quan; xen-devel@xxxxxxxxxxxxx; ian.jackson@xxxxxxxxxxxxx;
> > > tim@xxxxxxx; keir@xxxxxxx; ian.campbell@xxxxxxxxxx;
> > > jbeulich@xxxxxxxx
> > > Subject: Re: [Xen-devel] [PATCH 2/6] vTPM: add
> > > HVM_PARAM_STUBDOM_VTPM parameter for HVM virtual machine
> > >
> > > On Thu, 30 Oct 2014, Andrew Cooper wrote:
> > > > On 30/10/14 12:05, Xu, Quan wrote:
> > > > >
> > > > >> -----Original Message-----
> > > > >> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> > > > >> Sent: Thursday, October 30, 2014 7:50 PM
> > > > >> To: Xu, Quan; xen-devel@xxxxxxxxxxxxx
> > > > >> Cc: keir@xxxxxxx; ian.campbell@xxxxxxxxxx; tim@xxxxxxx;
> > > > >> ian.jackson@xxxxxxxxxxxxx; jbeulich@xxxxxxxx
> > > > >> Subject: Re: [Xen-devel] [PATCH 2/6] vTPM: add
> > > > >> HVM_PARAM_STUBDOM_VTPM parameter for HVM virtual machine
> > > > >>
> > > > >> On 30/10/14 07:38, Quan Xu wrote:
> > > > >>> Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
> > > > >> What is the purpose of this parameter?  A patch like this is
> > > > >> currently unacceptable, especially as the libxl hunk indicates
> > > > >> that the parameter name does not match whatever information you
> > > > >> are putting
> > > into it.
> > > > >>
> > > > > Thanks for your suggestion.
> > > > > This parameter tell the Qemu whether to register Qemu vTPM
> > > > > frontend in
> > > xen_hvm_init().
> > > > > Qemu will get the parameter value by xc_get_hvm_param(). How can
> > > > > I
> > > change it?
> > > >
> > > > This is surely something which should be a command line parameter
> > > > to qemu, or perhaps for qemu to read out of xenstore.
> > > >
> > > > An HVM param is entirely inappropriate for this purpose, in my opinion.
> > >
> > > I agree that an HVM param for this might not the best way to do it,
> > > but I can see why Quan did it that way as we already have a few key
> > > parameters passed to QEMU that way.
> > >
> > > A QEMU command line option, QMP command or xenstore key would be
> better.
> >
> > If hvm param is not the best way, I think xenstore key would be better.
> >
> > Below is part of Qemu patch, that's why I add HVM_PARAM_STUBDOM_VTPM
> param.
> > xen_vtpm_register() is similar to xen_be_register()
> >
> > ### Qemu : xen_hvm_init() [xen-hvm.c]###
> > +#ifdef CONFIG_TPM_XENSTUBDOMS
> > +    xc_get_hvm_param(xen_xc, xen_domid,
> HVM_PARAM_STUBDOM_VTPM, &stubdom_vtpm);
> > +    if (stubdom_vtpm) {
> > +        xen_vtpm_register(&xen_vtpmdev_ops);
> > +    }
> > +#endif
> 
> I think I would need to see the rest of the QEMU patches to be able to tell 
> you
> which way I think is best.
> In this context is vtpm an emulated device or a PV backend?
> 

I have submitted Qemu patch series -- "[PATCH 0/4] Qemu-Xen-vTPM: enable Xen 
stubdom vTPM for   HVM virtual machine"

It is not an emulated device. It is a pv backend. This driver transfers any 
request/repond between TPM xenstubdoms driver 
and Xen vTPM stubdom, and facilitates communications between Xen vTPM stubdom 
domain and vTPM xenstubdoms driver

Quan 

> >     xen_be_register("console", &xen_console_ops);
> >     xen_be_register("vkbd", &xen_kbdmouse_ops);
> >     xen_be_register("qdisk", &xen_blkdev_ops);
> >     xen_read_physmap(state);
> > ##### Qemu ####
> >
> >
> > Quan
> >

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