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Re: [Xen-devel] Doamin crash when trying to install disk encryption (PointSec) on Windows HVM

  • To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • From: Tom Rotenberg <tom.rotenberg@xxxxxxxxx>
  • Date: Wed, 22 Apr 2009 17:04:36 +0300
  • Cc: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Wed, 22 Apr 2009 07:05:11 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
Keir,
Just to make sure, i am using the following patch, in order to disable the vm86 acceleration:

diff -r cdc044f665dc xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c    Wed Apr 22 11:26:37 2009 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c    Wed Apr 22 17:03:20 2009 +0300
@@ -829,7 +829,7 @@
        
         if ( seg == x86_seg_tr )
         {
-            if ( v->domain->arch.hvm_domain.params[HVM_PARAM_VM86_TSS] )
+            if (0)
             {
                 sel = 0;
                 attr = vm86_tr_attr;

Is this OK?

Tom

2009/4/22 Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Yes, the safest way to be sure is probably to replace the if() statement in
vmx_set_segment_register() that tests HVM_PARAM_VM86_TSS with if(0). That is
the only place in Xen that checks HVM_PARAM_VM86_TSS. Then you can
re-build/install Xen and be sure that vm86 accel must be disabled.

 -- Keir

On 22/04/2009 14:52, "Tom Rotenberg" <tom.rotenberg@xxxxxxxxx> wrote:

> So, do u suggest, that i will set HVM_PARAM_VM86_TSS to 0, and re-check it?
>
> 2009/4/22 Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>> At 14:34 +0100 on 22 Apr (1240410866), Keir Fraser wrote:
>>> It could be an issue with the vm86 acceleration, possibly. I'm pretty sure
>>> the guest would have to IRET from protected mode to enter vm86 mode itself,
>>> and we don't emulate that. Tim: what would we need to do to disable the vm86
>>> acceleration for testing purposes? You suggested not setting VM86_TSS param
>>> from hvmloader, but I couldn't convince myself what effect that would
>>> actually have as the logic in Xen is non-trivial.
>>
>> Yes; if HVM_PARAM_VM86_TSS is zero, vmx_set_segment_register() will
>> always set the tss bit in the bitmap of segments that aren't safe to
>> enter VM86 with.
>>
>> Tim.
>>
>>>
>>>  -- Keir
>>>
>>> On 22/04/2009 14:23, "Tom Rotenberg" <tom.rotenberg@xxxxxxxxx> wrote:
>>>
>>>> Tim,
>>>>
>>>> so what does it mean? could it be that we have a bug in the real mode
>>>> emulation, which causes the segment state to be invalid (maybe it's because
>>>> of
>>>> a bug in the patch that Keir made for me, which emulated the LLDT, and the
>>>> LTR
>>>> instructions)?
>>>>
>>>> Keir suggested to trace back where the problem (segment state) occured, and
>>>> from there to try and find the bug which caused it. Do u have any better
>>>> suggestion for solving this?
>>>>
>>>> Tom
>>>>
>>>> 2009/4/22 Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>>>>> At 13:39 +0100 on 22 Apr (1240407546), Tom Rotenberg wrote:
>>>>>> Keir,
>>>>>>
>>>>>> I have tried your latest patch, and it looks like now it passes the
>>>>>> emulation problem. However,  now the domain crashes with the following
>>>>>> error:
>>>>>>
>>>>>> (XEN) HVM1: Booting from 0000:7c00
>>>>>> (XEN) Failed vm entry (exit reason 0x80000021) caused by invalid guest
>>>>>> state
>>>>>> (0).
>>>>>> (XEN) ************* VMCS Area **************
>>>>>> (XEN) *** Guest State ***
>>>>>> (XEN) CR0: actual=0x0000000080010039, shadow=0x0000000080000019,
>>>>>> gh_mask=ffffffffffffffff
>>>>>> (XEN) CR4: actual=0x0000000000002060, shadow=0x0000000000000000,
>>>>>> gh_mask=ffffffffffffffff
>>>>>> (XEN) CR3: actual=0x000000000a213a20, target_count=0
>>>>>> (XEN)      target0=0000000000000000, target1=0000000000000000
>>>>>> (XEN)      target2=0000000000000000, target3=0000000000000000
>>>>>> (XEN) RSP = 0x0000000000000080 (0x0000000000000080)  RIP =
>>>>>> 0x000000000000002a (0x000000000000002a)
>>>>>> (XEN) RFLAGS=0x0000000000023202 (0x0000000000023202)  DR7 =
>>>>>> 0x0000000000000400
>>>>>
>>>>> Looks like we're trying to VMENTER in virtual 8086 mode but without
>>>>> tidying up the segment state.  That could either be the guest entering
>>>>> virtual 8086 mode itself or Xen entering vitrual 8086 mode to emulate
>>>>> real mode, but Xen is always careful to make the segment state agree
>>>>> with Intel's rather strict requrements when it does that.
>>>>>
>>>>> Tim.
>>>>>
>>>>>
>>>>>> (XEN) Sysenter RSP=0000000000000000 CS:RIP=0000:0000000000000000
>>>>>> (XEN) CS: sel=0x0060, attr=0x0c09b, limit=0xffffffff,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) DS: sel=0x0068, attr=0x0c093, limit=0xffffffff,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) SS: sel=0x0070, attr=0x0c093, limit=0xfc000fff,
>>>>>> base=0x000000000020ba62
>>>>>> (XEN) ES: sel=0x0068, attr=0x0c093, limit=0xffffffff,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) FS: sel=0x0068, attr=0x0c093, limit=0xffffffff,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) GS: sel=0x0068, attr=0x0c093, limit=0xffffffff,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) GDTR:                           limit=0x00001dd8,
>>>>>> base=0x0000000000200000
>>>>>> (XEN) LDTR: sel=0x0000, attr=0x1c000, limit=0xffffffff,
>>>>>> base=0x0000000000000000
>>>>>> (XEN) IDTR:                           limit=0x00000188,
>>>>>> base=0x0000000000201df0
>>>>>> (XEN) TR: sel=0x0058, attr=0x0008b, limit=0x0000ffff,
>>>>>> base=0x0000000000201ff2
>>>>>> (XEN) Guest PAT = 0x0000000000000000
>>>>>> (XEN) TSC Offset = ffffffe4920110b7
>>>>>> (XEN) DebugCtl=0000000000000000 DebugExceptions=0000000000000000
>>>>>> (XEN) Interruptibility=0001 ActivityState=0000
>>>>>> (XEN) *** Host State ***
>>>>>> (XEN) RSP = 0xffff83007e4f7fa0  RIP = 0xffff828c8019aa20
>>>>>> (XEN) CS=e008 DS=0000 ES=0000 FS=0000 GS=0000 SS=0000 TR=e040
>>>>>> (XEN) FSBase=0000000000000000 GSBase=0000000000000000
>>>>>> TRBase=ffff828c802a8b00
>>>>>> (XEN) GDTBase=ffff83007e9a3000 IDTBase=ffff83007e62e010
>>>>>> (XEN) CR0=0000000080050033 CR3=000000007cfdc000 CR4=00000000000026f0
>>>>>> (XEN) Sysenter RSP=ffff83007e4f7fd0 CS:RIP=e008:ffff828c801c7290
>>>>>> (XEN) Host PAT = 0x0000000000000000
>>>>>> (XEN) *** Control State ***
>>>>>> (XEN) PinBased=0000003f CPUBased=b6a1e7fe SecondaryExec=00000041
>>>>>> (XEN) EntryControls=000011ff ExitControls=0003efff
>>>>>> (XEN) ExceptionBitmap=00044080
>>>>>> (XEN) VMEntry: intr_info=80000b0b errcode=00001eac ilen=00000000
>>>>>> (XEN) VMExit: intr_info=00000000 errcode=00008000 ilen=00000000
>>>>>> (XEN)         reason=80000021 qualification=00000000
>>>>>> (XEN) IDTVectoring: info=00000000 errcode=00000000
>>>>>> (XEN) TPR Threshold = 0x00
>>>>>> (XEN) EPT pointer = 0x0000000000000000
>>>>>> (XEN) Virtual processor ID = 0x0000
>>>>>> (XEN) **************************************
>>>>>> (XEN) domain_crash called from vmx.c:2218
>>>>>> (XEN) Domain 1 (vcpu#0) crashed on cpu#1:
>>>>>> (XEN) ----[ Xen-3.4.0-rc3-pre  x86_64  debug=n  Not tainted ]----
>>>>>> (XEN) CPU:    1
>>>>>> (XEN) RIP:    0060:[<000000000000002a>]
>>>>>> (XEN) RFLAGS: 0000000000023202   CONTEXT: hvm guest
>>>>>> (XEN) rax: 0000000000000007   rbx: 0000000000001490   rcx:
>>>>>> 0000000000000000
>>>>>> (XEN) rdx: 0000000000001da8   rsi: 0000000000000000   rdi:
>>>>>> 0000000000000000
>>>>>> (XEN) rbp: 0000000000008ebf   rsp: 0000000000000080   r8:
>>>>>>  0000000000000000
>>>>>> (XEN) r9:  0000000000000000   r10: 0000000000000000   r11:
>>>>>> 0000000000000000
>>>>>> (XEN) r12: 0000000000000000   r13: 0000000000000000   r14:
>>>>>> 0000000000000000
>>>>>> (XEN) r15: 0000000000000000   cr0: 0000000080000019   cr4:
>>>>>> 0000000000000000
>>>>>> (XEN) cr3: 0000000001443000   cr2: 0000000000000000
>>>>>> (XEN) ds: 0068   es: 0068   fs: 0068   gs: 0068   ss: 0070   cs: 0060
>>>>>>
>>>>>> Could it be, that the real mode emulation code has a bug? What does this
>>>>>> error means?
>>>>>>
>>>>>> Tom
>>>>>>
>>>>>> 2009/4/22 Keir Fraser
>>>>>> <keir.fraser@xxxxxxxxxxxxx<mailto:keir.fraser@xxxxxxxxxxxxx>>
>>>>>> On 22/04/2009 12:18, "Tom Rotenberg"
>>>>>> <tom.rotenberg@xxxxxxxxx<mailto:tom.rotenberg@xxxxxxxxx>> wrote:
>>>>>>
>>>>>>> Keir,
>>>>>>>
>>>>>>> I have applied your patch, and it seemed to work. However, the domain
>>>>>>> still
>>>>>>> crashes, and now it looks like it's because of the 'LTR' instruction.
>>>>>>
>>>>>> Try the attached patch. It replaces the one I sent last time, and
>>>>>> emulates
>>>>>> both LLDT and LTR.
>>>>>>
>>>>>>  -- Keir
>>>>>>
>>>>>
>>>>> Content-Description: ATT00001.txt
>>>>>> _______________________________________________
>>>>>> Xen-devel mailing list
>>>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>>>> http://lists.xensource.com/xen-devel
>>>>>
>>>>>
>>>>> --
>>>>> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>>>>> Principal Software Engineer, Citrix Systems (R&D) Ltd.
>>>>> [Company #02300071, SL9 0DZ, UK.]
>>>>
>>>
>>>
>>
>> --
>> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>> Principal Software Engineer, Citrix Systems (R&D) Ltd.
>> [Company #02300071, SL9 0DZ, UK.]
>


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