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RE: [Xen-devel] Guest TSC and Xen (Intel and AMD feedback please)


  • To: <dan.magenheimer@xxxxxxxxxx>, "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Zhang, Li" <li.zhang@xxxxxxxxx>
  • Date: Tue, 8 Jul 2008 10:59:40 +0800
  • Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
  • Delivery-date: Mon, 07 Jul 2008 20:00:11 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcjboIivPTuddHlLSIGPaPhte5VM5wASModQADA1FBAAMHiVIAAjyGRgAKf/8qAAAXmfcAABT0gw
  • Thread-topic: [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

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