Re: kvm running on core1 wants guest os on core2 to execute a pre-defined program

[Gleb Natapov <gleb@redhat.com>]

On Sun, Feb 17, 2013 at 02:46:28AM +0000, zhangzhi wrote:
> I have been studying some stuff about KVM and sincerely hope that someone is
> willing to reply to this mail. 
> As we know, If physical NIC interrupt is received on physical CPU 0 which is in
> root mode and the hypervisor determines that this is a network packet targeted
> to the emulated NIC for a VM at the same time this VM is running a user program
> in guest mode on physical CPU 1.
> My question is: 
> At this time can hypervisor running on CPU 0 *actively* interrupt VM and make it
> run the corresponding interrupt handler to handle the incoming network data
> packet? CPU 1 which is running a user program is not supposed to vm-exit
> considering the performance effect, so I can not use the inter-processor
> interrupt(IPI) to cause the CPU1 to leave guest mode and exit to the hypervisor.
> 
With current generation of CPUs you will have to use IPI to make CPU1
vmexit and inject interrupt on the next vmentry. Future CPU will allow to
inject interrupt into a running guest without vmexit. On Intel this is
called "posted interrupts".
 
--
			Gleb.