[vbox-dev] SysyemCall in VirtualBOx

[Sander van Leeuwen]

  There are two modes for delivering interrupts and traps to a guest 
with software virtualization:
- trap forwarding: 'int xx' generates a #GP that the hypervisor 
intercepts, after which it interprets the instruction and (usually) 
forwards to the guest IDT entry
- IDT gate passthrough; in certain specific cases we use trampoline code 
to directly call the guest's IDT handler (int xx -> trampoline handler 
-> guest idt handler; no hypervisor interaction occurs)

Neither method applies to hardware virtualization (VT-x/AMD-V) as the 
guest execution mode is identical to what it expects (no ring 
compression; guest ring 0 code running in ring 1).


On 10/15/2010 6:05 PM, Francesco Di Paolo wrote:
> hello there, i
> i'd like to have some informations in regards to how the hypervisor 
> takes over when a system call(int 0x80) occurs in the guest OS. How it 
> is managed the passage from Ring3 to Ring1. What i'm facing is 
> understand what is going on when an application in the guest OS 
> invokes a system call(i didn't get if it is involved the host kernel 
> and its IDT or if there are interactions only between the application 
> and the guest kernel). If you could give us some suggestions, we would 
> be very grateful.
>
>
> _______________________________________________
> vbox-dev mailing list
> vbox-dev at virtualbox.org
> http://vbox.innotek.de/mailman/listinfo/vbox-dev


-- 
Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet

--
Sander van Leeuwen | Senior Staff Engineer, VirtualBox
Oracle Virtualization

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