Hi, Dan
This is the patch which I think it has been completed VT. But there is an
instable issue. The reason may be from that this interception is not bound to
timer mode yet.
Thanks
--Li
> -----Original Message-----
> From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> Sent: Tuesday, July 08, 2008 11:34 AM
> To: Zhang, Li; Xen-Devel (E-mail)
> Cc: Tian, Kevin; dan.magenheimer@xxxxxxxxxx
> Subject: RE: [Xen-devel] Guest TSC and Xen (Intel and AMD feedback please)
>
> Thanks Kevin and Li --
>
> A couple of questions:
>
> 1) If the EXITING flag to be set in vmcs.c is to be controlled by a xen boot
> option, would this work:
>
> static int opt_softtsc = 0;
> boolean_param("softtsc", opt_softtsc);
> :
> min = /* original code */
> if (opt_softtsc) min |= CPU_BASED_RDTSC_EXITING;
>
> 2) In vmx_rdtsc_intercept(/* need regs as param*/) if we change the
> rdtscll(tsc) to be tmptsc = hvm_get_guest_tsc() and then set regs->edx amd
> regs->eax from tmptsc, are we almost done?
>
> 3) Des Linux or Windows use the CR4.TSD flag and, if so, what code gets
> called
> to force the trap?
>
> 4) Does Linux or Windows use RDMSR/WRMSR of tsc? Is there already code
> somewhere to emulate WRMSR of tsc?
>
> Sorry I am not very familar with the details of the ia32 instruction set.
>
> Thanks,
> Dan
>
> > -----Original Message-----
> > From: Zhang, Li [mailto:li.zhang@xxxxxxxxx]
> > Sent: Monday, July 07, 2008 9:00 PM
> > To: dan.magenheimer@xxxxxxxxxx; Xen-Devel (E-mail)
> > Cc: Tian, Kevin
> > Subject: RE: [Xen-devel] Guest TSC and Xen (Intel and AMD
> > feedback please)
> >
> >
> > Hi, Dan
> > This seems not to be enough. I will cook another patch.
> >
> > > -----Original Message-----
> > > From: Zhang, Li
> > > Sent: Tuesday, July 08, 2008 10:28 AM
> > > To: Tian, Kevin; 'dan.magenheimer@xxxxxxxxxx'; 'Xen-Devel (E-mail)'
> > > Subject: RE: [Xen-devel] Guest TSC and Xen (Intel and AMD
> > feedback please)
> > >
> > > Hi, Dan
> > >
> > > I just add some code to produce vmexit. The function
> > vmx_rdtsc_intercept()
> > > is not completed. It is needed to add some code to get the
> > guest tsc.
> > >
> > > Thanks
> > > --Li
> > >
> > > > -----Original Message-----
> > > > From: Tian, Kevin
> > > > Sent: Tuesday, July 08, 2008 9:39 AM
> > > > To: 'dan.magenheimer@xxxxxxxxxx'; Xen-Devel (E-mail)
> > > > Cc: Zhang, Li
> > > > Subject: RE: [Xen-devel] Guest TSC and Xen (Intel and
> > AMD feedback please)
> > > >
> > > > >From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> > > > >Sent: 2008年7月5日 1:32
> > > > >
> > > > >> >Is this something that you (or Intel in general)
> > could look at?
> > > > >> >I would be happy to participate but I don't think I
> > understand
> > > > >> >VT well enough. Once the trap occurs, I suppose
> > Xen system time
> > > > >> >could be used as the virtual TSC, possibly scaled up.
> > > > >> >
> > > > >>
> > > > >> There should be tiny related to VT, as only turning
> > on some bit to
> > > > >> allow RDTSC trapping and then the rest stuff should be common
> > > > >> how to handle it. We'll take a look, but can't
> > commit the time due
> > > > >> to other scheduled bandwidth. But if you'd like to
> > jump in early
> > > > >> we definitely can help with VT side.
> > > > >
> > > > >If you can post a patch with code that:
> > > > >
> > > > >1) declares a boolean global variable: softtsc = 0
> > > > >2) if the variable is set, a rdtsc instruction in any hvm
> > > > > domain causes a trap
> > > > >3) the trap handler just does a physical rdtsc and returns
> > > > >
> > > > >then I could probably take it from there.
> > > >
> > > > OK, and Li in CC will take a look and bake a patch for you.
> > > >
> > > > Thanks,
> > > > Kevin
> >
tsc.patch
Description: tsc.patch
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