Re: Doamin crash when trying to install disk encryption (PointSec) on Windows HVM

[Keir Fraser <keir.fraser@eu.citrix.com>]

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All task switches are emulated, so you can add tracing to hvm_task_switch()
to check if a switch has occurred. An alternative is that the guest did
another LTR while not being emulated?

If you want to remember the last VMEXIT, you¹ll have to add code to store
state away somewhere to pick up on the next VMENTRY.

 -- Keir

On 23/04/2009 15:08, "Tom Rotenberg" <tom.rotenberg@gmail.com> wrote:

> About the TR, i have re-checked it, and it seems like the TR value is still
> 0x58, althoug the LTR operation put 0x50 into it. Since, i looked at the LTR
> code you sent me, and it seems ok, i tend to suspect, that there was some kind
> of (hardware) task switch, which changed the TR value without me knowing, is
> it possible? because otherwise, i can't really explain why the TR value is
> different than what was loaded from the LTR operation...
> 
> BTW - how can i track what was the previous VMEXIT before this last VMENTRY
> which caused the exception? i think, that probably the last VMEXIT caused the
> "change" to vm86 mode, and this is waht causes the problem...
> 
> Tom
> 
> 2009/4/23 Keir Fraser <keir.fraser@eu.citrix.com>
>> On 23/04/2009 12:44, "Tom Rotenberg" <tom.rotenberg@gmail.com> wrote:
>> 
>>> > However, from the VMCS dump, i saw data, which doesn't seem compatible
>>> with
>>> > this, as the LDTR sellector is indeed 0, but has attributes and limit
>>> > different from zero (although it should have been totaly disabled, by the
>>> > LLDT, no?).
>> 
>> The 'unused' flag in the attributes word is set (bit 16) so LDTR is okay.
>> 
>>> > And more important, the TR selector is 0x58, although from the LTR, it was
>>> > supposed to be 0x50, no?
>> 
>> If 0x50 was loaded then the selector should certainly be 0x50.
>> 
>>  -- Keir
>> 
>>> > (of-course it's possible that there were other instructions who changed it
>>> > back, however, i am wondering if there is a problem here).
>> 
>> 
> 


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