Re: [PATCH] vtdt: add a missing change (RE: Re: xen guest hang with TSC_DEADLINE)

[Christoph Egger <Christoph.Egger@amd.com>]

On Wednesday 05 January 2011 11:11:46 Wei, Gang wrote:
> Christoph Egger wrote on 2011-01-04:
> >>>>> c/s 22529 and 22530 cause a xen guest hang.
> >>>>>
> >>>>> While "normal" guests like Linux and NetBSD boot fine I boot Xen
> >>>>> itself as a xen guest for my nested virtualization.
> >>>>>
> >>>>> When I do that then the guest dom0 hangs at boot when it tries
> >>>>> to initialize the first vcpu.
> >>>>> The bug is introduced somewhere in c/s 22529 and triggers with
> >>>>> c/s 22530.
> >>>>
> >>>> Can you enable apic_timer debug info var hvm_debug and give more
> >>>> serial port log around the guest dom0 hangs? I used to test xen
> >>>> guest, it works well expect that it boot a little bit slowly.
> >>>
> >>> This is the log output I get with TSC_DEADLINE feature enabled:
> >>
> >> Just found one change was missed while the whole patch was checked in.
> >> Apply below patch, it should be ok now.
> >>
> >> diff -r 0133cf2a72f5 xen/arch/x86/hvm/vlapic.c
> >> --- a/xen/arch/x86/hvm/vlapic.c	Fri Dec 24 10:56:29 2010 +0000
> >> +++ b/xen/arch/x86/hvm/vlapic.c	Tue Dec 28 16:53:06 2010 +0800
> >> @@ -56,7 +56,7 @@ static unsigned int vlapic_lvt_mask[VLAP  static
> >> unsigned int vlapic_lvt_mask[VLAPIC_LVT_NUM] =  {
> >>       /* LVTT */
> >> -     LVT_MASK | APIC_TIMER_MODE_PERIODIC,
> >> +     LVT_MASK | APIC_TIMER_MODE_MASK,
> >>       /* LVTTHMR */
> >>       LVT_MASK | APIC_MODE_MASK,
> >>       /* LVTPC */
> >> Jimmy
> >
> > The hang is still reproducable with this change. Sorry.
>
> Can you still see below line in the serial log? Is there anything
> different?
>
> (XEN) [HVM:1.0] <vlapic_tdt_msr_set> ignore tsc deadline msr write

This one disappeared.

My serial log is flooded with

(XEN) [HVM:1.1] <vlapic_tdt_msr_set> delta[0x00003c7e619fbf47]
(XEN) [HVM:1.3] <vlapic_tdt_msr_set> delta[0x00003c7e619fc6de]
(XEN) [HVM:1.2] <vlapic_tdt_msr_set> delta[0x00003c7e619fc577]
(XEN) [HVM:1.1] <vlapic_tdt_msr_set> tdt_msr[0x00000031ea5955ea], 
gtsc[0x00000031e936c509], gtime[0x0000001a5ff3f942]
(XEN) [HVM:1.3] <vlapic_tdt_msr_set> tdt_msr[0x00000031eb83efd8], 
gtsc[0x00000031ea615816], gtime[0x0000001a60917e60]
(XEN) [HVM:1.2] <vlapic_tdt_msr_set> tdt_msr[0x00000031ecae3dd2], 
gtsc[0x00000031eb8ba626], gtime[0x0000001a612ee444]

But I never see a line starting with [HVM:1.0] or [HVM:1.4]. My guest
has four virtual vcpus.

nested dom0 output did not change.


>
> In my side, I can see above line, and nested dom0 will hang while booting
> if without this change. But things become ok after applying this change. So
> could you give more details after apply this change (again, serial log,
> nested dom0 output, etc) ?
>
> Jimmy



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