Re: [RFC][PATCH] ignore set_cr3 GP fault in non-pae mode

[Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>]

Ryan Harper wrote:
> * Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-09-19 03:58]:
>   
>> Ryan Harper wrote:
>>     
>>>> We have a test which verifies #GP is not caused by setting the bits on
>>>> either AMD or Intel chips.  "Stray" bits can get turned on in some cases
>>>> when switching between 64-bit, PAE and non-PAE address modes.
>>>>
>>>> Were you testing on a 64-bit host kernel?
>>>>    
>>>>         
>>> 64-bit Host running 32-bit KVM Guest. VMware-server shouldn't be seeing
>>> anything 64-bit AFAIK.
>>>  
>>>       
>> If the host is 64-bit, so is the guest, although the guest can choose to 
>> ignore the 64-bit capabilities (and 32-bit guest OSes do; but VMware 
>> might be doing something tricky).
>>     
>
> Hrm.  I'm not sure I understand the distiction you are making.  I'll
> give a 32-bit host a try without the patch and see if I see the same
> behavior.
>   

On a 64-bit host, even if the guest kernel is 32-bit the guest could 
still detect the ability to run in 64-bit mode.  The thinking is that 
VMware may be detecting 64-bit capabilities and doing something weird.  
I think that's somewhat orthogonal to this patch.  It seems like 
ignoring setting of reserved bits is the right thing to do in 32-bit 
mode.  Does anyone disagree with that?

Regards,

Anthony Liguori


-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/