Re: Scheduling of VCPUs and allocation of Guest Physical Memory

[Sukanto Ghosh <sukanto@cse.iitb.ac.in>]

>> But what about the interrupts that need to be delivered immediately 
>> and while the VM is executing (assume interrupts are enabled in the 
>> guest). Is any kind of signal-based mechanism employed to force a 
>> VM-exit ?
>>
>
> Sending a signal to a task that is executing guest code will force it 
> to exit to userspace immediately.  The in-kernel interrupt controller 
> emulation also forces guest exits by sending inter-processor interrupts.
>
>
I saw that KVM has guest SMP support upto 4 VCPUs. Are these VCPUs 
modelled as threads of 'the process representing the VM' ?

If it is, then, when a signal is sent to the that process by the QEMU 
process, shouldn't all of the VCPUs (for that VM) exit to the userspace ?

Who does this management of delivering the interrupt to the VCPU for 
which it is intended for ? And, how ?


Also, while going through the KVM source, I found mention of opaque at 
many places. What does 'opaque' refer to ? What is an opaque data ?



Thanks and Regards,
Sukanto