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.
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