RE: VCPU Structure

[Kaushik Barde <kbarde@huawei.com>]

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Satyajeet

 

I think, describing exact details of "memory integrity block" and its
relevance to VCPU modification would help the conversation.

 

-Kaushik

 

From: xen-devel-bounces@lists.xensource.com
[mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Dan Magenheimer
Sent: Monday, November 08, 2010 5:43 AM
To: Nimgaonkar, Satyajeet; Xen Devel
Subject: RE: [Xen-devel] VCPU Structure

 

I'm not asking you to describe the Xen functionality.  I am asking you to
describe in more detail the modification to the processor
functionality/behavior that you are trying to achieve.  I don't know what a
"simple memory integrity block" does and searching for it doesn't find
anything helpful.


Nearly all instructions in the VCPU are executed directly in hardware (by
the physical CPU == PCPU).  The only way to change the VCPU behavior is to
cause some kind of trap or fault or exception to occur on the PCPU, which
gets intercepted by the processor and then control is turned over to
privileged software (in this case Xen).  Xen has a lot of code that handles
many many different kinds of traps/faults/exceptions.  Your VCPU will need
to execute an instruction that causes a trap or fault or exception and then
you will need to add code to Xen to recognize your special one and do
something special with it.


Does that help?


Dan

 

From: Nimgaonkar, Satyajeet [mailto:SatyajeetNimgaonkar@my.unt.edu] 
Sent: Sunday, November 07, 2010 10:14 PM
To: Dan Magenheimer; Xen Devel
Subject: RE: [Xen-devel] VCPU Structure

 

Hi,
   I am sorry if I have not provided provided enough information about the
functionality that I want to implement. But my problem is that even I new to
Xen and trying to understand my way around it. With regards to the
functionality that I want to implement, I wish to modify the behavior of the
VCPU in xen. As a starting point, I just want to add simple memory integrity
block within the VCPU. I am really not sure what would be the best way to do
this so I need some suggestions on that too. 
   Thanks. I hope that helps too.

Regards,
Satyajeet

  _____  

From: Dan Magenheimer [dan.magenheimer@oracle.com]
Sent: Thursday, November 04, 2010 7:25 PM
To: Nimgaonkar, Satyajeet; Xen Devel
Subject: RE: [Xen-devel] VCPU Structure

I think nobody is responding because you haven't provided enough information
about what it is you are trying to do... and resending the same message
doesn't help.


For example, if you are "extending" the instruction set (e.g. using an
illegal opcode to do something useful), that would be very different than
trapping memory accesses that meet a certain criteria.

 

From: Nimgaonkar, Satyajeet [mailto:SatyajeetNimgaonkar@my.unt.edu] 
Sent: Thursday, November 04, 2010 2:52 PM
To: Xen Devel; Dan Magenheimer
Subject: [Xen-devel] VCPU Structure

 

 Hi,
    I want to modify the VCPU structure to implement memory integrity
functionality (i.e. memory hash function), such that the VCPU functionality
incorporates memory integrity. Also once this is done, I want make sure that
the VMs i create (Dom0 and Domu) run on this modified VCPU itself.
    Can anyone please tell me where should I look for to implement this.
    Thank you very much.

Regards,
Satyajeet


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