RE: [Xen-devel] hvm iret

["Cui, Dexuan" <dexuan.cui@xxxxxxxxx>]

For HVM guest, i.e., VMX guest, the execution of IRET is similar to that on native system, but of course there are important differences :)  -- you should read the related chapters (i.e., “event injection”) in Intel Software Developer’s Manual 3B, and you should also look at the Xen code (i.e., the vioapic.c, vlapic.c, vmx/vmx.c, vmx/intr.c in the directory xen/arch/x86/hvm/).

 

Note: HVM guest doesn’t touch physical interrupt (and the physical pic/ioapic /local_apic) --here we don’t consider VT-d; 

Xen only “injects” *virtual* interrupts into HVM guest with the help of the emulation of Device Model.

When HVM vcpu is running, if a physical interrupt happens, a VMExit  will occur to interrupt the execution of the HVM vcpu, then Xen handles the physical interrupt.

 

-- Dexuan

---

From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ashish Bijlani
Sent: 2007年10月21日 4:21
To: Xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] hvm iret

could anybody guide me to some pointers on iret execution by hvms. 
something like what happens when a HVM executes an iret instruction? when is the 
physical interrupt acknowledged so that IOAPIC can send more interrupts. thanks. 

-a
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